Arguments or proofs for the Existence of God have been proposed
by philosophers, theologians, and other thinkers. These arguments have
an epistemological dimension (how can one know that God exists?) and an
ontological dimension (what is the nature of God’s being?).
If God is conceived as the Supreme Being, Being-itself, the source and Creator of all beings, or in other similar ways, the question of his existence is of primordial importance. It is indeed paradoxical that there would be a need to prove the existence of this Being of all beings, yet that is precisely the situation philosophers and theologians find themselves in, since God cannot be perceived by human senses. The overall theistic explanation is that God transcends finite forms of being and thus cannot be reached directly by finite human minds, although indirect rational proofs may be possible. The opposite position concludes that God cannot be perceived because he simply does not exist. This leads to the essential question of the meaning of "existence" when the notion is applied to God. Thus, one’s understanding of God—rational, intuitive, religious, or other—affects one’s approach to the question of his existence.
Given the variety of approaches, it has been rightly suggested by people such as Ninian Smart that if the existence of God is to be taken seriously, rational or philosophical insights about it need to be combined with the various other aspects of religious revelation, such as the experiential dimension, the moral dimension, and the mythical dimension.
Context of the arguments
The three traditional proofs of God’s existence
The attempt to provide proofs or arguments for the existence of God is known as natural theology. This undertaking has traditionally consisted of three key arguments: The ontological, cosmological, and teleological arguments. Such proofs may seem futile in the contemporary context. However, one must understand that in the middle ages, when the famous proofs of God first appeared, the issue was not to find out logically if God exists or not. God's existence was a given, based on faith. Thinkers like Anselm of Canterbury and Thomas Aquinas in Christianity, Maimonides in Judaism, and Avicenna or Averroes in Islam mostly questioned whether God's existence could be known only through faith, or whether it was also possible to prove it by using the philosophical (rational) method and, if so, how. These arguments were meant to buttress the arguments of faith and to defend that faith from those who would challenge it.
The contemporary approach
The contemporary mind looks at the question very differently. First, the existence of God no longer appears to be an indisputable reality, even to those who believe in him. Second, the very idea that it is possible to prove the existence of God seems questionable at best. The scientific mindset is used to considering that only measurable objects of scientific inquiry can be known for certain, and even this certainty is being shaken in a postmodern context. Spiritual, transcendent, and invisible entities such as God can only be the object of opinion or conjecture, never of certain knowledge. Next comes a trend that has had its representatives throughout the centuries: God, afterlife, and similar issues can only be known through intuitive insight or spiritual revelation. Some just know that it is so—rational proofs are not only powerless, they are inappropriate to begin with.
The problem is that different people come to different conclusions, intuitively or otherwise. The quintessentially philosophical question, here, is how can one know? This affects one's entire attitude towards what he considers reality, not only the question of God.
The focus of the proofs of God's existence has thus shifted over the centuries. Today, their main purpose would be to show that it is likely that a supreme being exists, i.e., more likely than not. Discussion of the anthropic principle, for example, highlights the fact that science cannot be used to prove that God does not exist. At most, it is a draw.
Philosophical and religious Issues
What is God? (Definition of God's existence)
What is God? One approach to this problem, following the works of Ludwig Wittgenstein, would be to attempt to extract a definition of "God" from the way that particular word is used. What is meant when one says, "God" or "gods"? However, this line of questioning runs immediately into trouble if it tries to give a universal notion of "God," since that word and its equivalents have been used in very different ways throughout history.
Today in the West, the term "God" typically refers to a monotheistic concept of a Supreme Being that is unlike any other being. Classical theism asserts that God possesses every possible perfection, including such qualities as omniscience, omnipotence, and perfect benevolence.
In the Advaita Vedanta school of Hinduism, reality is ultimately seen as being a single, qualityless, changeless being called nirguna Brahman, understood to be beyond "ordinary" human comprehension. Advaitin philosophy introduces the concept of saguna Brahman or Ishvara as a way of talking about Brahman to people. Ishvara, in turn, is ascribed such qualities as omniscience, omnipotence, and benevolence.
Polytheistic religions use the word "god" for multiple beings with varying degrees of power and abilities. Such deities are thus neither perceived to be all-powerful nor always benevolent. The myths of polytheism often cover a deeper layer of philosophical reflection that hints at a united being that takes precedence even over the gods.
The issue of existence
The seemingly innocuous question about the exact meaning of the word “existence” cannot be avoided in the context of the proofs for God’s existence. What does it mean to exist when the term is applied to God? This, of course, leads back to an understanding of God. At least since Aristotle, there has been an unending debate over the difference between “existence,” “being,” and “essence.” In general terms, to exist simply means to be there—to be real. It also implies that one is talking about a specific entity, generally perceived by the senses. However, one can also say that goodness or evil exist in this world. What is meant by that statement is immediately clear, though it is hard to pinpoint what their being really is.
The problem with stating that God exists is that by doing so one seems to imply that he is an entity, albeit an elusive one. In this way, he is reduced to the level of a particular being, though perhaps the highest or most perfect one. Many have perceived that, if God is to have any reality, it must be of an entirely different order that cannot be qualified as existence. Twentieth century theologian Paul Tillich is one of them. For him, “God does not exist.” It is even a sign of atheism to say that he does, as it implies a denial of God’s real being, Being-itself, the ground of all being. Similarly, twentieth century philosopher Martin Heidegger has decried the use of what he called "onto-theology," where God is objectified as if he were a particular being. In medieval theology and philosophy already, Thomas Aquinas had stated that God is beyond essence and existence.
This distinction between existence and being is proper to the western philosophical landscape. It does not appear, for instance, in the thought systems of the Far East. This is no accident: The notion of a personal, theistic God is proper to the religions of the west. The issue of God’s existence does not arise in Buddhism or Confucianism for instance.
The problem of the supernatural
Another problem immediately posed by the question of the existence of a God is that traditional beliefs usually grant God various supernatural powers. Religious apologists offer the supernatural abilities of God as explanation of the inability of empirical methods to prove God's existence. In Karl Popper's philosophy of science, the assertion of the existence of a supernatural God would be a non-falsifiable hypothesis, not amenable to scientific investigation.
Thus, logical positivists, such as Rudolph Carnap and A. J. Ayer, view any talk of gods as literally nonsense. For the logical positivists and adherents of similar schools of thought, statements about religious or other transcendent experiences could not have a truth-value, and were deemed to be without meaning. Even for other schools of thought, the question of God appears at the same time as the culmination of philosophical inquiry (since it deals with the ultimate question) and the point where that inquiry must stop due to its own limitations.
One cannot be said to "know" something just because one believes it. Knowledge is, from an epistemological standpoint, distinguished from belief by justification through proofs or arguments. Much of the disagreement about "proofs" of God's existence is due to different conceptions not only of the term "God" but also the terms "proof," "truth," and "knowledge." Religious belief from revelation or enlightenment is fundamentally different.
Different conclusions as to the existence of God often rest on different criteria for deciding what methods are appropriate for deciding if something is true or not. Some examples include:
- Whether logic counts as evidence concerning the quality of existence
- Whether subjective experience count as evidence for objective reality
- Whether either logic or evidence can rule in or out the supernatural
The religious perspective is almost always linked to some sort of philosophical explanation. However, its emphasis is on God as a living reality, accessible through revelation or introspection, rather than rational discussion. Early Christian thinkers like Augustine of Hippo believed that humans had a natural ability to perceive the reality of God. In such a perspective, arguments or proofs do not occupy an important position: It is not necessary to prove the existence of something obvious; what is needed is only an explanation.
Much later thinkers, including eighteenth century German philosopher David Friedrich Fries, thought that human reason culminated in a direct apprehension of the divine reality, something akin to intellectual intuition, a faculty Immanuel Kant insisted humans do not have. The problem with this perspective is that of intersubjectivity: How can one communicate her certainty to another person and ascertain that it is identical, other than by assuming a priori that it is so?
The Indian religion of Sikhism offers an elaborate version of that position. The fundamental belief of Sikhism is that God exists, not merely as an idea or concept, but as a "Real Entity," indescribable yet knowable and perceivable to anyone who is prepared to dedicate the time and energy to become perceptive to God’s persona. The Sikh gurus never spoke about proofs of the existence of God; for them, God is too real and obvious to need any logical proof.
Guru Arjan says: "God is beyond color and form, yet His presence is clearly visible" (GG, 74), and again, "Nanak's Lord transcends the world as well as the scriptures of the east and the west, and yet he is clearly manifest" (GG, 397).
Types of arguments
Different types of classification have been suggested. Some arguments are a priori, that is, independent from experience. First and foremost, this is the case of the ontological argument, which seeks to show the necessity of God from the very notion of God. Most arguments are a posteriori, that is, they try to show evidence for the presence of a God from certain features of reality. For example, the cosmological argument intends to show that there must be an ultimate, uncaused cause (God) to the existing universe. The teleological argument assumes that the harmony and purposefulness evident throughout nature represents an evidence of intelligent design, thus of a supreme designer (God). Still another well-known a posteriori argument is the argument from the degrees of perfection, developed by Aquinas, which argues that the various degrees of goodness, beauty, truth, etc. in the world resemble something which is the maximum (best, most beautiful, truest, etc.), and that this something is God. These a posteriori arguments are empirical, because they are based on observation, while the ontological argument is strictly metaphysical, because it only involves reflection that transcends sense data.
But there are so many arguments that their richness defies classification. Since the very notion of God has a universal (or even trans-universal) dimension, it is normal that evidence for God’s existence has been searched for by using nearly every approach and every faculty. Besides logic and rational deduction, ethics, science, spiritual intuition, and even the authority of scripture and tradition are some of the dimensions that have been explored to that end.
Given these many arguments, it is debatable whether they are all different or whether they are all not merely parts of one and the same argument. While all such proofs would end in the same way, by asserting the existence of God, they do not all start at the same place. Aquinas calls them aptly Viæ: roads to the apprehension of God which all open on the same highway.
Also, any argument for or against the existence of God must be considered in context. Few people, if any, will be swayed by the persuasiveness of one single argument if they are not previously so inclined. Neither is the use of arguments by philosophers generally meant to persuade in this way. There is often a synergy between complementary arguments. This clearly results from a careful examination of the three main historical arguments.
The ontological argument
According to this argument, God, as the Supreme Being, must exist by definition. It is an a priori argument. Saint Anselm of Canterbury and Rene Descartes have used this argument, but Immanuel Kant dismissed it, as he did the other two arguments. The common-sense approach finds it much less obvious than the cosmological and teleological arguments. The notion that the mere idea of God implies God’s existence may even seem strange, yet contemporary philosophers find it fascinating. Attempts are regularly being made to prove its validity by using formal logic. Paul Tillich’s attempt to show that the unconditioned is a necessary function of the mind can be seen as another contemporary form of the argument, though Tillich never made that claim.
The argument works by examining the concept of God, and arguing that it implies the actual existence of God; that is, if one can conceive of God, then God exists—it is thus self-contradictory to state that God does not exist. This is obviously a controversial position, and the ontological argument has a long history of detractors and defenders. The argument's different versions arise mainly from using different concepts of God as the starting point.
The ontological argument was first proposed by Anselm of Canterbury (1033–1109) in chapter 2 of the Proslogion, even though he did not directly use the expression. He argued that there are necessary beings—things that cannot not exist—and contingent beings—things that may or may not exist, but whose existence is not necessary. He starts with his famous definition, or necessary assumption about the nature of God: "Now we believe that [the Lord] is something than which nothing greater can be imagined."
Then Anselm asks: does God exist? In sum, he concludes that, whether one believes in God or not, she cannot avoid at least having the notion of that greatest possible being in her mind. Now Anselm introduces another assumption: "And certainly that than which a greater cannot be imagined cannot be in the understanding alone. For if it is at least in the understanding alone, it can be imagined to be in reality too, which is greater."
It would therefore be contradictory to assume that the greatest possible being exists in the understanding alone, because then, it would always be possible to imagine an even greater being—that which actually exists.
From that contradiction, Anselm draws his conclusion: "There exists, therefore, beyond doubt something than which a greater cannot be imagined,,both in the understanding and in reality."
In his Proslogon 3, Anselm made another a priori argument for God, this time based on the idea of necessary existence. He claimed that if God is that than which nothing greater can be conceived, it is better to be necessary than contingent. Therefore God must be necessary.
Philosophical assumptions underlying the argument
In order to understand the place this argument has in the history of philosophy, it is important to understand the essence of the argument in the context of the influence of Hellenic philosophy on Christianity.
First, Anselm's argument stemmed from the philosophical school of realism. Realism was the dominant philosophical school of Anselm's day. According to realism, and in contrast to nominalism, things such as "greenness" and "bigness" were known as universals, which had a real existence outside the human imagination, in an abstract realm of ideas, as described by Plato. Accordingly, if a concept could be formed in the human mind (as was his concept of God), then it had a real existence in the abstract realm of the universals. In essence, if one could imagine God, God existed.
Anselm also held that there were two types of existence: Necessary existence and contingent existence. Contingent existence is a state of existence which depends on something else—that is, if something else were not the case, the object in question would not exist. Necessary existence, by contrast, depends on nothing. Something that necessarily exists will exist no matter what. It cannot not exist.
Criticisms and objections
One of the earliest recorded objections to Anselm's argument was raised by his contemporary, Gaunilo of Marmoutiers. Gaunilo invited his readers to think of the greatest, or most perfect, conceivable island. As a matter of fact, it is likely that no such island actually exists, even though it can be conceived. In short, to conclude that something exists because existence would make it more perfect makes no sense.
Such objections always depend upon the accuracy of the analogy. In the case of Gaunilo’s island, there is no single concept of a perfect island, because perfection here can only mean what is perfect for one particular person, rather than perfect in itself. The notion of the perfect being, however, isn't relative to any individual; it's the notion of a being that is maximally great—not for an individual, but great universally.
Another rationale is attributed to Douglas Gasking (1911–1994). Gasking makes a paradoxical statement to show that one could just as well use the argument to prove that God does not exist: Greatness depends on one’s merit in accomplishing something. For God to create the world even though he doesn’t exist would imply the greatest merit (overcoming the greatest handicap). Hence, for God to be the greatest, he must not exist.
Defenders of Anselm would reject the thesis that disability and handicap are things that make a creator greater. The merit of that particular objection is that it highlights the problematic nature of the word “exist” and that it challenges the traditional view of God as a Supreme, detached Being who created the world with no effort at all.
Obviously, Anselm thought this argument was valid and persuasive, and it still has occasional defenders, but many, perhaps most, contemporary philosophers believe that the ontological argument, at least as Anselm articulated it, does not stand up to strict logical scrutiny. Others, like Gottfried Leibniz, Norman Malcolm, Charles Hartshorne, Kurt Gödel, and Alvin Plantinga have reformulated the argument in an attempt to revive it.
Descartes' ontological arguments
René Descartes (1596-1650) composed a number of ontological arguments which differed from Anselm's formulation in important ways. Generally speaking, it is less a formal argument than a natural intuition.
Descartes wrote in the Fifth Meditation on First Philosophy:
The intuition above can be formally described as follows:But if the mere fact that I can produce from my thought the idea of something entails that everything which I clearly and distinctly perceive to belong to that thing really does belong to it, is not this a possible basis for another argument to prove the existence of God? Certainly, the idea of God, or a supremely perfect being, is one that I find within me just as surely as the idea of any shape or number. And my understanding that it belongs to his nature that he always exists is no less clear and distinct than is the case when I prove of any shape or number that some property belongs to its nature (AT 7:65; CSM 2:45).
- Whatever one clearly and distinctly perceives to be contained in the idea of something is true of that thing.
- One clearly and distinctly perceives that necessary existence is contained in the idea of God.
- Therefore, God exists.
In another, less formal statement of his argument, he draws an analogy between belief in the existence of God and the geometric demonstration. Mathematical demonstrations can lead to absolute certainty through complicated demonstrations that cannot be immediately evident. In the case of God, things are much simpler: “For what is more manifest than the fact that the supreme being exists, or that God, to whose essence alone existence belongs, exists” (AT 7:68-69; CSM 2:47).
Plantinga's modal form and contemporary discussion
Contemporary American philosopher Alvin Plantinga has created another version of the argument, one where the conclusion follows from the premises, assuming axiom S5 of modal logic. The axiom S5 says that if a proposition is possibly necessarily true, then it is necessarily true. If, then, a maximally great being possibly exists, it exists. Richard M. Gale has argued that the "possibility premise" begs the question, because here "possibly necessarily" is basically the same as "necessarily."
A very different approach has recently been attempted by A. R. Pruss, who starts with the eighth/ninth century C.E. Indian philosopher Samkara's dictum that if something is impossible, then one cannot have a perception (even a non-veridical one) that it is the case. If mystics perceive the existence of a maximally great being, it follows that the existence of a maximally great being is at least possible. One difficulty in this argument is that one might misinterpret the content of one's experience, and hence the mystic might be incorrect even in a cautious description of an experience as an experience "as of a maximally great being."
The cosmological argument
The premise of the cosmological argument is that all existing beings are dependent beings (they cannot exist by themselves, they did not create themselves), therefore, there must be a self-existent being, i.e., a being whose existence is accounted for by its own nature. The problem is to define such a being. Either there is an ultimate cause that is fundamentally different from humanity, or people have infinite regress. That ultimate being would have to be of a different nature, and would have to be a different type of cause. This argument assumes the Principle of Sufficient Reason: there must be an explanation for the existence of every being, thing, or quality. But Buddhism, Aristotle, and Jean-Paul Sartre, to name a few, feel that there is no problem with the assumption that the universe has always existed. It is simply there.
There are three basic variants of this argument in its classic form: The argument from causation in esse, the argument from causation in fieri, and the argument from contingency. The cosmological argument does not attempt to prove anything about the first cause or about God, except to argue that such a cause must exist.
Origins of the argument
Plato and Aristotle both posited first cause arguments, though each with certain notable caveats. Plato (c. 427–c. 347 B.C.E.) believed that a "demiurge" was the creator of the cosmos. For Plato, the demiurge lacked the supernatural ability to create ex nihilo or out of nothing. The demiurge was only able to organize the pre-existent chaos, itself subjected to the purely physical laws of necessity (Ananke). Ultimately, for Plato, all is derived from the Soul, or Self-Mover, a non-material entity.
Aristotle (c. 384–322 B.C.E.) also put forth the idea of a creator of the cosmos, often referred to as the "Unmoved Prime Mover" in his work Metaphysics. For Aristotle, as for Plato, the underlying "stuff" of the universe always was in existence and always would be (which in turn follows Parmenides' famous statement that "nothing can come from nothing"). Aristotle posited an underlying ousia (an essence or substance) of which the universe is composed. It is the ousia which the Prime Mover organized and set into motion, not by acting, but by being the center of attraction, hence the Unmoved Mover.
Thomas Aquinas (c. 1225–1274 C.E.), the best known theologian of the Middle Ages, adapted the argument to form one of the earliest and the most influential versions of the cosmological argument. His conception of first cause is the idea that the universe must have been caused by something which was itself uncaused, which he asserted was God.
Framed as a formal proof, the first cause argument can be stated as follows:
- Every effect has a cause(s).
- Nothing can cause itself.
- A causal chain cannot be of infinite length.
- Therefore, there must be a first cause—something which is not an effect.
The argument from contingency
Aquinas follows Aristotle in claiming that there must be something which explains why the universe exists. Since the universe could, under different circumstances, conceivably not exist—that is to say, since it is contingent—its existence must have a cause. And that cause cannot simply be another contingent thing, it must be something which exists by necessity.
The German philosopher Gottfried Leibniz made a somewhat similar argument with his Principle of Sufficient Reason, in 1714. He wrote: "There can be found no fact that is true or existent, or any true proposition, without there being a sufficient reason for its being so and not otherwise, although we cannot know these reasons in most cases." He formulated the cosmological argument succinctly: "Why is there something rather than nothing? The sufficient reason…is found in a substance which…is a necessary Being bearing the reason for its existence within itself."
In esse and in fieri
"In esse" and "in fieri" are Latin expressions from medieval scholasticism. They make an important distinction. God can be seen as a remote first cause who starts everything and then is no longer needed (in fieri, i.e., “in becoming”). That is the position of deism, where God is merely a logical assumption to explain how everything started. Once the universe is set into motion, according to that view, things pretty much proceed mechanically—God is no longer needed. But God can also be seen as the Creator and permanent sustainer of the universe (in esse, i.e., “in existence”). In that case, God is not only the first cause who started everything, but God also maintains the existence of everything all the time. Creation then is a permanent event. This second view is less mechanistic, but also more mysterious: How is God’s action invisibly present in every moment?
As a general trend, the modern slants on the cosmological argument tend to lean very strongly towards an in fieri argument to the extent that they are trying to explain how it all started. The question, there, is: What brought the whole of existence into motion? On the other hand, based on the biological sciences, some have insisted on the necessity of an original life force working in organic processes. For instance, scientists know how wounds heal, but they don’t have the slightest idea why the healing process is set into motion. In everyday language, an answer would be that God is permanently working through the organism.
Counterarguments and objections
Several objections to the cosmological argument have been raised. The most obvious one runs as follows: "If God created the universe, who created God?" If everything needs a cause (the basic assumption of the cosmological argument), then why doesn’t God? Skeptics have thus spoken of a “trilemma” (a triple dilemma) that is not solved by the argument: Either one has infinite regress (every entity is caused by another entity, which is caused by yet another, and so on indefinitely); or one dogmatically asserts that there is a God as First Cause (without even trying to explain why this should be the case); or one has circular reasoning: God explains the existence of the world, but this brings it back to the starting point, the fact that there is a world means that there must be a God, which is circular reasoning. The implication of this position is that it is useless to try to find an ultimate cause of things.
Another objection is that even if one accepts the argument as a proof of a First Cause, it does not identify this first cause with "God." The argument simply names the First Cause as "God" without proving that it has the characteristics that that name implies. It is also troublesome to use the title "creator," as this would imply assuming that the "creator" has some sort of intelligence. At best, one may be able to call this first cause a "supernatural" first cause.
Opponents also point out that the cosmological argument applies temporal concepts to situations where time does not exist. If God created the universe, he also created time. The nonsensical question “what was there before God created time?” would ensue.
And some, including German philosopher Immanuel Kant, have contended that applying the category of causality to a hypothetical First Cause is entirely inappropriate. Cause and effect apply to finite events within this universe. How such a relationship could exist between an unknowable First Cause and the universe is beyond the human grasp.
Criticisms of counterarguments
A response to criticism will naturally incorporate some of the very elements that make up that criticism. First and foremost, it must be admitted that the argument cannot yield much information, if any, on the nature of the First Cause, or God, other than that there must be a Being that is such a cause. The argument cannot be a substitute for faith or spiritual insights, much less church dogma.
The objection that this First Cause must have a cause itself, resulting in circular reasoning, can be answered by stating the following: The very argument assumes that there must be a Being that is of a fundamentally different nature from all existing entities in that it can be its own cause. Thus, the argument cannot go beyond suggesting the reality of such a Being, without making any further statements on its nature. It can also hint to the fact that denying it means accepting a meaningless and unexplained universe without a cause. In other words, assuming the reality of such a Prime Being does not offer a full answer, but it does clarify the nature of the issue and its possible implications.
Thus, almost all physical cosmologists subscribe to a theory of universal origin that is effectively dualistic in nature. On careful consideration of the Big Bang, for example, some sort of "cause," itself not caused by "natural" forces of the universe (causa sui, i.e., its own cause), appears to be inescapable.
That includes time. Time is understood as "natural" in substance, while the uncaused cause is not natural and therefore not operable in time. Aquinas understood the Divine as outside of time, viewing all of time, indeed being present in all of time, simultaneously.
When one looks for the origin of the universe he effectively postulate "substances," forces or circumstances that are "pre-natural." Understanding that time itself is part of the natural order, one cannot say "before" time, but that at the instant of the Big Bang, conditions that cannot exist under natural physical laws caused an inflationary expansion of matter and energy.
Currently, the theory of the cosmological history of the universe most widely accepted by astronomers and astrophysicists includes an apparent first event—the Big Bang—the expansion of all known matter and energy from a superdense, singular point at some finite time in the past.
The cosmological argument as elaborated in antiquity and in the Middle Ages was purely based on logical philosophical reflection: There is a need for a First Cause. There was not the slightest notion of how that Original Being might have caused the world to exist. In trying to explain the emergence of the world, theologians generally relied on Creatio ex nihilo, the belief that God created the world out of nothing. How a spiritual God could have caused our material world to exist remained a mystery. The modality of creation was understood in terms of the seven days of creation of the Genesis narrative. Thus, the cosmological argument consisted of a mixture of philosophical speculation and religious dogma.
This situation changed dramatically with the advent of twentieth century science, in particular physics and astronomy. A “how” began to emerge, at least on the level of hypothesis. By extrapolating based on actual scientific measurements, scientists were able to offer a somewhat clear picture of the very first moments of existence of our universe, which led them to suggest various ways in which this beginning may have been set into motion. Though the Big Bang itself is still nothing but a hypothesis in need of revision, it thus offers a concrete framework in which to visualize, as much as possible, what may have happened.
Other twentieth century scientific theories, such as quantum physics and the theory of relativity can and have been used to argue either way in issues relating to a First Cause. It would be naïve to expect any scientific theory to offer a definitive response to a philosophical question; what such theories do offer is, again, a framework for understanding the issue more realistically, especially as far as the nature of time and space is concerned.
In his famous Antinomies of pure reason, Immanuel Kant had argued against the cosmological argument because saying that the cosmos has a beginning makes as much or as little sense as saying that it does not. If there was a beginning, the question is, what was there before? If not, there is no end to the causal chain, which the mind equally cannot accept. Hence, Kant says, people have to admit that God, as thing in itself, is wholly beyond the phenomenal world that humanity can understand. Contemporary astrophysics shows that the everyday notion of time and space does not fully apply to the extreme conditions of a hypothetical starting point. This in itself represents a formidable argument against common-sense objections of the type used by Kant.
A commonly stated workaround for the cosmological argument is the nature of time. The Big Bang is said to be the start of both space and time, so the question "What was there before the universe?" makes no sense; the concept of "before" becomes meaningless when considering a situation without time. This has been put forward by Stephen Hawking, who said that asking what occurred before the Big Bang is like asking what is north of the North Pole. Science is presently still learning the nature of time, and how the visible universe originated, therefore to an extent certain questions are partially unanswered.
The other look at the question
The three proofs have been developed in the Western world and primarily apply to a theistic view: There is one God, transcendent creator of the universe. People are used to considering that everything must have a cause, so the universe must have a prime cause. But what if there is something wrong with the assumption that the universe must have a cause, like every individual entity?
In East Asia, including India and China, the notion of a creator is not entirely absent. It appears in various creation myths (mythical stories on how the universe came into being), just like it does in other parts of the world. But there is also a strong tendency not to look at things in this way. There is little focus on this question in religious traditions and thought systems such as Buddhism. The focus is more on attitudes towards the human condition, rather than on speculation on the origin of the universe. This resonates with many in the West as well.
The teleological argument
The teleological argument (argument from design) is essentially an inductive and intuitive argument. It states that there must be an intelligent designer (God) who is responsible for order, harmony, and beauty in the world. It is an argument for the existence of God based on perceived evidence of order, purpose, design and/or direction in nature. The word "teleological" is derived from the Greek word telos, meaning end or purpose. Teleology is the supposition that there is purpose or directive principle in the works and processes of nature. But there are objections: The universe is far from perfect (David Hume), and what if it is the product of trial and error (Charles Darwin)?
The basic argument can be stated as follows:
- X is too (complex, orderly, adaptive, apparently purposeful, and/or beautiful) to have occurred randomly or accidentally.
- Therefore, X must have been created by a (sentient, intelligent, wise, and/or purposeful) being.
- God is that (sentient, intelligent, wise, and/or purposeful) being.
- Therefore, God exists.
History of the argument
Plato posited a "demiurge" of supreme wisdom and intelligence as the creator of the cosmos in his work Timaeus. Plato's teleological perspective is also built upon the analysis of a priori order and structure in the world which he had already presented in The Republic.
Aristotle's views also have very strong aspects of a teleological argument, specifically that of a Prime Mover who, so to speak, looks ahead in setting the cosmos into motion. Indeed, Aristotle argued that all nature reflects inherent purposiveness and direction (his so-called final cause).
Cicero (c. 106–c. 43 B.C.E.) also made one of the earliest known teleological arguments. In de Natura Deorum (On the Nature of the Gods) Cicero stated, "The divine power is to be found in a principle of reason which pervades the whole of nature." He was writing from the cultural background of the Roman religion. In Roman mythology the creator goddess, Gaia was borrowed from Greek mythology. "When you see a sundial or a water-clock, you see that it tells the time by design and not by chance. How then can you imagine that the universe as a whole is devoid of purpose and intelligence, when it embraces everything, including these artifacts themselves and their artificers" (Cicero, De Natura Deorum, ii. 34).
Augustine of Hippo (354–430 C.E.) presented a classic teleological perspective in his work, City of God. He did not, however, make a formal argument for the existence of God; rather, God's existence is already presumed and Augustine is giving a proposed view of God's teleology.
Aquinas and the scholastics
The most notable scholastics (c. 1100-1500 C.E.) who put forth teleological arguments were Averroes (Ibn-Rushd) and Thomas Aquinas. Averroes was writing in Spain from an Islamic perspective in the latter half of the twelfth century. Averroes argues based mainly upon Aristotle's Physics, in essence that the combination of order and continual motion in the universe cannot be accidental, and requires a Prime Mover, a Supreme Principle, which is in itself pure intelligence.
This would set the stage for Aquinas in the thirteenth century. Aquinas makes a specific, compact, and famous version of the teleological argument, the fifth of his five proofs for the existence of God in his Summa Theologiae:
The British empiricistsThe fifth way is taken from the governance of the world. We see that things which lack knowledge, such as natural bodies, act for an end, and this is evident from their acting always, or nearly always, in the same way, so as to obtain the best result. Hence it is plain that they achieve their end, not fortuitously, but designedly. Now whatever lacks knowledge cannot move towards an end, unless it be directed by some being endowed with knowledge and intelligence; as the arrow is directed by the archer. Therefore, some intelligent being exists by whom all natural things are directed to their end; and this being we call God.
Starting with John Locke, seventeenth and eighteenth century British empiricists opened the way to a scientific perspective based on experience that left little room for assumptions about an a priori divine purpose. Locke’s successor, George Berkeley, would try to counterbalance that tendency. As part of this approach, Berkeley included in his text, Alciphron, a variant of the teleological argument which held that the order one sees in nature is the language or handwriting of God. David Hume, in the mid-eighteenth century, attempted a number of interesting refutations, including one that arguably foreshadows Darwin's theory, but he reaches no conclusion.
The watchmaker analogy
The “watchmaker analogy” framing the argument with reference to a timepiece dates back to Cicero, as quoted above. It was also used by Voltaire, who remarked: "If a watch proves the existence of a watchmaker but the universe does not prove the existence of a great Architect, then I consent to be called a fool." Today the analogy is usually associated with the theologian William Paley, who presented the argument in his book Natural Theology, published in 1802. As a theology student, Charles Darwin found Paley's arguments compelling, then later developed his theory in the Origin of Species, which puts forward an alternative explanation for complexity in nature.
Many others have countered the watch argument, such as by showing that highly complex systems can be produced by a series of very small randomly-generated steps. Richard Dawkins' book The Blind Watchmaker (1986) is one of the best-known examples of this approach outside philosophy and theology.
More recently, proponents of intelligent design have reframed the argument as the concept of irreducible complexity. This argument asserts that each substructure of an organism confers no benefit on its own, and therefore cannot have been selected by an evolutionary mechanism. The argument then posits that the probability of all the substructures being created in a single mutation is too low to be considered possible. Critics describe this as an argument from ignorance which assumes that substructures have not changed in function, and give illustrations of how gradual replacement by a series of advantageous variations can lead to the evolution of structures claimed as being irreducibly complex.
The anthropic principle and fine-tuned universe arguments
A well-known contemporary variation of the argument is the so-called anthropic principle, which says that the seemingly arbitrary and unrelated constants in physics have one strange thing in common—these are precisely the values needed to have a universe capable of producing human life (hence, “anthropic,” from the Greek word for human). Even a tiny difference would have made the appearance of our universe impossible. The universe gives the appearance that it was designed to support life on earth, another example of Paley’s watch.
In this line of reasoning, speculation about the vast, perhaps infinite, range of possible conditions in which life could not exist is compared to the speculated improbability of achieving conditions in which life does exist, and then interpreted as indicating a fine-tuned universe specifically designed so human life is possible. This view is well articulated by John D. Barrow and Frank J. Tipler in The Anthropic Cosmological Principle (1986).
Some of the estimated proportions involved in cosmic "fine-tuning" are remarkable. John Polkinghorne, for instance, pointed out in 1985 that just one factor among many in the cosmos, the difference between expansive and contractive forces in the expanding cosmos according to then-currently accepted theory, depends upon an extremely fine balance of the total energy involved to within one in 1060, a 61-digit number; equivalent to taking aim from Earth and hitting an inch-wide target at the farthest reaches of the observable universe. George Wald, also in 1985, wrote that the conditions for something as fundamental as the atom depend on a balance of forces to within one in 1018. All this, they argue, hints at the existence of a designer.
Many highly regarded thinkers have weighed in on both sides the debate. A counter-argument to the anthropic principle is that one could manipulate statistics to define any number of natural situations that are extremely improbable, but that have happened nevertheless. By the critics' view a key problem in terms of being able to verify whether the hypothesized probabilities are correct, is that the improbable conditions were identified after the event, so they cannot be checked by experiment. And, there is no ability to sample a large enough set of alternatives. An analogy from common experience where the odds can be readily calculated is given by John Allen Paulos in Innumeracy: Mathematical Illiteracy and its Consequences (1989). Paulos calculates that the probability of a particular hand in a card game is approximately one in 600 billion. It would be absurd to examine the hand carefully, calculate the odds, and then assert that it must not have been randomly dealt. This perspective on the issue of improbability appears to bolster the position that characteristics of Earth that allow it to sustain life could be just a fortunate and/or accidental "hit," so to speak. However, this does not take into account the difference between a set of particular cards—a very unlikely combination, but of no particular complexity—and a complex organic or physical combination.
As for the cosmological argument, the teleological argument has inherent limitations that need to be acknowledged even by its proponents. First of all, the argument says nothing about the nature of the designer, or God, other than that he must be of a nature able to originate design without being in need of it himself (an “undersigned” designer). The reality of such a Being is posited, rather than explained.
Also, even if the argument from design proves the existence of a powerful intelligent designer, it does not prove that the designer is a theistic God. Voltaire noted this from his deistic perspective. Voltaire observed,
In his Critique of Judgment and elsewhere, Kant put considerable emphasis on the apparent evidence of design in nature and the mind’s need to conclude from it that there must be a designer. This, he nevertheless concluded, cannot be taken as a theoretical proof of the reality of such a designer or God. It merely shows that the world looks “as if” it had been created by such a designer, thus leaving the possible reality of that designer as an open question that will never be answered.[From this one argument, I cannot conclude anything more, except that it is probable that an intelligent and superior being has prepared and shaped matter with dexterity; I cannot conclude from this argument alone that this being has made the matter out of nothing or that he is infinite in any sense [i.e. that he is God].
Kant’s follower Jakob Friedrich Fries (1773-1843) interestingly tried to separate the notion of design from its verifiable manifestations. As a man of the Enlightenment, Fries had a mechanical view of the universe. He considered that the material world consisted of a network of causes and effects that needed no further explanation. If it weren’t for its extreme complexity, future outcomes of that system could be predicted in their minutest detail. Seeing purpose in it would be a mere projection based on the existing outcome. However, Fries also considered that the human mind has the inherent capacity to perceive the reality of purpose through intuition, or Ahndung. He thus rejected the traditional application of the teleological argument in favor of an intuitive one. Actual purpose can be perceived through the intuition of beauty in creation and human beings, thus allowing humanity to reach the realm of the infinite, which is that of God.
The premises of the argument assume that because life is complex, it must have been designed. However, the design claim is often attacked as a simple argument from ignorance.
A designed organism would also be a contradiction to evolutionary theory. As most biologists support the theory of biological evolution by means of natural selection, they reject the first premise of the argument, arguing that evolution is not only an alternative explanation for the complexity of life but a better explanation with more supporting evidence. A range of chemical reactions could take place in living organisms, forming chemicals with increasingly complex properties and ways of interacting. Over very long periods of time self-replicating structures could arise and later form DNA. Thus biologists commonly view the design argument as an unimpressive argument for the existence of a god. The argument from design is thus a major element in the debate between creationism and evolution.
Argument from poor design
The argument from poor design is based on the premise that a creator God would create organisms that have optimal design, but that many organisms have significant defects. This point was already made by eighteenth century philosopher David Hume. The term incompetent design has been coined by Donald Wise to describe aspects of nature that are flawed in design.
One well-know examples of "poor design" would be the existence of the appendix in the human body. That small part of the intestine is apparently useless and is often the source of trouble. Many other observations of the same type, applying to the human body or other entities, have been made.
"Poor design" is consistent with the predictions of the scientific theory of evolution by means of natural selection. This predicts that features that were evolved for certain uses, are then reused or co-opted for different uses, or abandoned altogether. The argument from poor design is one of the arguments used by Charles Darwin; modern proponents have included Stephen Jay Gould and Richard Dawkins, who argue that such features can be explained as a consequence of the gradual, cumulative nature of the evolutionary process.
The argument from poor design is generally criticized by showing how an apparently poor design or useless feature actually has a purpose that has simply been ignored or undetected. Even where the existence of useless features cannot be explained away, it can be argued that these are leftovers of a trial-and-error process by the designer. What this line of arguing does in the process is to present a view of the designer that is different from the traditional notion of a God who is in total control. If design and creation happens, it appears more realistically as a long, painstaking process towards an ultimate goal—a process in which many blind alleys have to be avoided.
Thus, the argument from poor design is sometimes interpreted as an argument against characteristics commonly attributed to God, such as omnipotence, omniscience, or personality. Or, it is used as an argument for the incompetence of God. Finally, certain features of life that seem to contradict the existence of a perfect designer, such as various forms of suffering, can be explained by the Human Fall away from God. The notion of a human fall, found in most religions, has in turn been used to show that the existence of a good God is self-contradictory.
Some have argued that there is no inherent contradiction between intelligent design and evolution. Certain religious perspectives may find nothing illogical about believing in a creator-deity who purposed evolution to propagate the emergence of life on earth. This position is becoming increasingly accepted today—indeed, Pope John Paul II put forward a position of exactly this kind.
The argument from the degrees of perfection
This argument was somewhat touched upon by Augustine and Anselm but developed later by Aquinas as the fourth of his five ways (Quinque Viae). All things in nature have various degrees of perfections such as goodness, truth, and nobility. If anything comes in degrees, it must be comparable to a maximum. The maximum in a genus is the cause of all in that genus. So, there must be a maximum of perfections such as goodness, truth, and nobility, i.e., the best, the truest, the noblest, etc. The maximum of perfections is God. This is sometimes called the Platonic argument because it talks about the existence of the Platonic "forms" along with the existence of God. One strength of this argument is that it can speak of many more attributes of God than the ontological, cosmological, and teleological arguments.
David Hume critiqued this argument by saying that since there is much evil and suffering in this world, a God of the maximum of perfections cannot exist.
The moral argument
Among all the proofs for God’s existence that have been attempted besides the main three proofs described above, the moral argument is the best known. This argument comes in different forms, all aiming to prove God’s existence from the evidence of morality in the world.
Kant’s moral argument
Kant introduced his famous formulation of the proof as a replacement for the three classic proofs, which he felt were hopeless attempts to derive certainty about God through theoretical knowledge. In his Critique of Practical Reason, Kant sought to replace theoretical certainty with the moral certainty of practical reason.
That certainty exists, Kant insisted, because of the following:
- The highest good is where moral virtue and happiness coincide.
- People are rationally obliged to attain the highest good.
- What people are obliged to attain, it must be possible for them to attain.
- If there is no God or afterlife, it is not possible to attain the highest good (summum bonum).
- God (or the afterlife) must exist.
Kant himself insisted that this argument could not lead to absolute theoretical certainty, but that people were rationally obliged to assume that this was so, because this is the only way the world could make sense. Kant’s position assumes that the universe is rational. It also assumes that the certainty one reaches through his argument is the culmination or rationality, whereas others would see in it a certainty of the intuitive type. The moral argument as presented by Kant has precisely been criticized for assuming a universal rational order and universal justice.
Other forms of the argument
All forms of the moral argument begin with the notion that there is a fundamental moral norm. That is, human beings are typically aware of actions as being right and wrong. This awareness seems to bind people toward certain obligations, regardless of their personal goals and ends. In this sense, moral qualities have the appearance of universality and objectivity.
According to the argument, the perceived absoluteness of morally binding commands can only be justified based on an absolute origin of these commands, i.e., God. For instance, it has often been stated that, if there is no God, anything goes. There is ultimately no reason for doing good, rather than evil.
To this, it has been objected that even in the absence of a God, humans can and often do abide by moral commands for their own sake. In addition, it is highly debatable whether there is one set of absolute moral commands. Many would insist that moral commands are conditioned culturally or otherwise.
Critics also point out this argument's appeal to a "divine command theory" of ethics. Objections to divine command theories of ethics are numerous, most stemming from forms of the Euthyphro dilemma. Is an action good because God commanded it, or did God command it because it is good? The first horn would imply that what is good is arbitrary; God decides what is right and wrong in the same way that a government decides which side of the street cars should drive on. The second horn would imply that God made his commands in accordance with transcendental facts that exist apart from God. God, then, would not be omnipotent.
Proponents of the argument maintain that this dilemma can be adequately resolved. Thomas Aquinas, for example, explains that God indeed commands something because it is good, but the reason it is good is that "good is an essential part of God's nature."
Other arguments for the existence of God
Countless other arguments have been proposed over the centuries. What follows is but a sampling.
- The "Will to Believe Doctrine" was pragmatist philosopher William James' attempt to prove God by showing that the adoption of theism as a hypothesis "works" in a believer's life. This doctrine depended heavily on James' pragmatic theory of truth where beliefs are proven by how they work when adopted rather than by proofs before they are believed (a form of the hypothetico-deductive method).
- Richard Swinburne, one of the foremost contemporary philosophers of religion, has suggested in his The Existence of God (2004) what can be called a hypothetical argument, according to which the existence of the God of monotheistic religions as they understand him should be treated first only as an "hypothesis" and then be tested or verified by observing the world which was supposedly created by him. The verification process using scientific and experiential data about the world, according to Swinburne, would make the hypothesis on God's existence more probable than improbable. Even though he is a supporter of the teleological argument, his use of a hypothetical method has made it more acceptable to people including atheists.
- Another class of philosophers asserts that the proofs for the existence of God present a fairly large probability, though not absolute certainty, as obscure points remain. In order to overcome these difficulties, either an act of the will, a religious experience, or the discernment of the misery of the world without God is necessary, so that finally the heart makes the decision. This view is maintained, among others, by the English statesman Arthur Balfour in his book The Foundations of Belief (1895).
- Subjective arguments mainly rely on the testimony or experience of certain witnesses, or the propositions of a specific revealed religion. The witness argument gives credibility to personal witnesses, in contemporary and past ages. A variation of this is the argument from miracles which relies on testimony of supernatural events to establish the existence of God. The "Christological argument" is specific to Christianity and asserts that Jesus' life as written in the New Testament establishes his credibility, so one can believe in the truth of his statements about God. An example of this argument is presented by C. S. Lewis in Mere Christianity. The "argument from common consent" or "majority argument" argues that people in all times and in different places have believed in God, so it is unlikely that he does not exist.
- The Scotch school, led by Thomas Reid, taught that the fact of the existence of God is accepted by one without knowledge of reasons but simply by a natural impulse. That God exists, this school said, is one of the chief metaphysical principles that humans accept not because they are evident in themselves or because they can be proved, but because common sense obliges one to accept them.
- The "Argument from a Proper Basis" argues that belief in God is "properly basic"—that is, similar to statements such as "I see a chair" or "I feel pain." Such beliefs are non-falsifiable and, thus, neither able to be proved nor disproved; they concern perceptual beliefs or indisputable mental states.
- In Germany, the school of Friedrich Heinrich Jacobi taught that reason is able to perceive the supersensible. Jacobi distinguished three faculties: sense, reason, and understanding. Just as sense has immediate perception of the material so has reason immediate perception of the immaterial, while the understanding brings these perceptions to our consciousness and unites them to one another. God's existence, then, cannot be proved. Jacobi, like Kant, rejected the absolute value of the principle of causality—it must be felt by the mind. A similar position was defended by Fries.
- In his Emile: Or, On Education, Jean-Jacques Rousseau asserted that when human understanding ponders over the existence of God it encounters nothing but contradictions; the impulses of the heart, however, are of more value than the understanding, and these proclaim clearly to one the truths of natural religion, namely, the existence of God and the immortality of the soul.
- The same theory was advocated in Germany by Friedrich Schleiermacher (d. 1834), who assumed an inner religious sense by means of which one feels religious truths. According to Schleiermacher, religion consists solely in this inner perception, and dogmatic doctrines are inessential. Many modern Protestant theologians follow in Schleiermacher's footsteps.
Each of the following arguments aims at showing that some particular conception of a god either is inherently meaningless, contradictory, or contradictory to known scientific and/or historical facts, and that therefore a god thus described does not exist.
Empirical arguments (against)
Empirical arguments depend on empirical data in order to prove their conclusions. In addition to those already indicated, several additional objections have been made:
- The pejorative expression God of the Gaps expresses one fundamental objection of many scientists against the notion of a divinity. It means that God is used as an explanation for as-of-yet unexplainable phenomena, even though there is no rational ground for such a belief. The mysterious word “God” simply covers up temporary ignorance. In history, church dogma was also used to counter scientific evidence in ways that defied reason, in order to avoid facing conclusions uncomfortable to the church.
- The argument from inconsistent revelations contests the existence of the deity called God as described in holy scriptures of monotheism, by identifying contradictions between different scriptures, contradictions within a single scripture, or contradictions between scripture and known facts.
- The problem of evil in general has been seen as evidence against the existence of an all-powerful and benevolent God (see article on theodicy).
- The argument from nonbelief contests the existence of an omnipotent god who wants humans to believe in him by arguing that such a god would do a better job of gathering believers. This argument is contested by the claim that God wants to test humans to see who has the most faith.
Deductive arguments attempt to prove their conclusions by deductive reasoning from true premises.
- The omnipotence paradox is one of many arguments which argue that the definitions or descriptions of a god are logically contradictory, demonstrating his non-existence. This paradox can be shown through questions such as: "Can God create a rock so big that [God] could not lift it?" Some may argue that this paradox is resolved by the argument that such a rock is an impossibility of human reality rather than the result of an imperfect God.
- One simple argument that the existence of a god is self-contradictory goes as follows: If God is defined as omniscient and omnipotent, then God has absolute knowledge of all events that will occur in the future, including all of his future actions, due to his omniscience. However, his omnipotence implies he has the power to act in a different manner than he predicted, thus implying that God's predictions about the future are fallible.
- The argument from free will contests the existence of an omniscient god who has free will by arguing that the two properties are contradictory
- It is alleged that there is a logical impossibility in theism: God is defined as an extra-temporal being, but also as an active creator. The argument suggests that the very act of creation is inconceivable and absurd beyond the restraints of time.
- The "no reason" argument tries to show that an omnipotent or perfect being would not have any reason to act in any way, specifically creating the universe, because it would have no desires since the very concept of desire is subjectively human. This raises the essential question of God’s nature and the purpose of creation.
- God is perfect. God also created man in his image. Man is imperfect, however. Therefore, God is imperfect and thus disproves himself.
As a summary, views on the existence of God can be roughly divided into three camps: theist, atheist, and agnostic. The theist and atheist camps can be further divided into two groups each, based on the belief of whether or not their position has been conclusively proven by the arguments.
God exists and this can be proved
The Thomist tradition and the dogmatic definition of the First Vatican Council affirm that it is a doctrine of the Roman Catholic Church that God's existence has been rationally demonstrated. Some other Christians in different denominations hold similar views.
As a theological defense of this view, one might cite Paul's claim that pagans were without excuse because "since the creation of the world [God's] invisible nature, namely, his eternal power and deity, has been clearly perceived in the things that have been made" (Romans 1:20).
God exists, but this cannot be proved or disproved
Others have suggested that the several logical and philosophical arguments for the existence of God miss the point. The proofs do not resolve that issue. Blaise Pascal suggested this objection in his Pensées, when he wrote, "The God of Abraham, Isaac, and Jacob—not the god of the philosophers!"
Some Christians note that the Christian faith teaches salvation by faith, and that faith has little to do with the believer's ability to comprehend. God's existence can never be demonstrated, either by empirical means or by philosophical argument. The most extreme example of this position is called fideism, which holds that that if God's existence were rationally demonstrable, faith in his existence would become superfluous.
The atheistic conclusion has two main variants.
The conclusion called strong, positive, or explicit atheism is the conclusion that God or gods do not exist. The strong atheist positively asserts this explicit non-existence, and may go further and claim that the existence of some or all gods is logically impossible. Similarly, explicit atheism may argue that any assertions about God are irrational and impossible. More fundamentally, a philosopher like Jean-Paul Sartre insists that the very notion of a Being whose essence determines everyone’s existence is certain to be false.
Negative or weak atheism concludes that there is no sufficient reason to believe in God. Weak atheists argue that merely pointing out the flaws or lack of soundness in all arguments for the existence of God is sufficient to show that God's existence is less probable than his nonexistence; by Ockham's razor (the principle that the most simple explanation is always to be preferred), the burden of proof lies on the advocate of that alternative which is less probable. Atheism is thus the "default" position.
Antony Flew has been a well-known supporter of such “negative” atheism. His alleged change towards a deistic position would be consistent with that form of atheism: Once confronted with unexpected evidence to the contrary (there seems to be a God after all), a negative atheist is prepared to change his position.
Agnostics hold that the existence of God is uncertain or unknown. Possible reasons for holding this view are a belief that the existence of any deity has not yet been sufficiently proven, that the existence of a deity cannot be proven, or that claims about the existence or non-existence of any deity make no sense. Agnostics may claim that it is not possible to have absolute or certain knowledge of supernatural beings or, alternatively, that while certainty may be possible, they personally have no such knowledge. Agnostics may or may not believe in gods based on personal convictions.
There exists a very large variety of historical approaches to the existence of God, whether they argue for or against it, intellectual or religious. There also exists objections to these various approaches. It seems that none of them are free from criticism. Then, is the existence of God something which is far from knowable with universally acceptable certainty, and therefore which one should be discouraged from seeking further to know?
An observation of current trends might help address this question. People now live in a culturally diverse society where absolute certainties are all but absent. So, it seems that the variety of approaches which have not necessarily been compatible with one another have softened their positions and lessened their claims. This change has been also due to the development of science; the "anthropic principle" established in science, for example, has shown at least that the existence of God is more probable than improbable. Last but not least, the general approach has become more holistic. People are more aware of dimensions other than the strictly logical, and they are aware that a purely logical approach has its own pitfalls.
As Ninian Smart puts it, the traditional proofs have survived and they still have their use, but it is suggestive, rather than decisive. Smart rightly notes that the often discredited rational proofs do have their rightful place in the debate, even though they may not touch the heart of the life of faith. The absence of an intellectual framework that makes sense has always been detrimental to faith, thus the quest for understanding should not be abandoned. For Smart, rational or philosophical insights about the existence of God are to be combined with the various other aspects of religious revelation, such as the experiential dimension, the moral dimension, and the mythical dimension.