Top 10 Best Arguments for the Existence of God

'Top Tens' seems to be a big theme on the internet these days. Considering that I have, in my many criticisms of 'pop' atheism, noted (again and again) their lack of engagement with serious theistic arguments, I thought I might write up a quick post about what I think are the 'top ten' best arguments for God's existence. I decide which arguments are the 'top' arguments based on three criteria: (1) the influence of the argument, both historically and today, (2) the persuasiveness of the argument, and (3) the quality of contemporary defences of the argument. I'll include a list of books and articles that defend these arguments, so that readers can do their own research.

Following the common trend on the internet, I'll start with No. 10 and work my way down to No. 1. Here is my 'top ten' list, plus some 'honourable mentions':

10. The Fine-Tuning Argument. A modern version of the design argument, developed in recent decades, this one focuses on recent developments in theoretical physics - specifically the discovery of the 'fine-tuning' of the fundamental constants of physics, e.g., the strength of gravity, the strength of the strong nuclear force, the rate of cosmic expansion following the 'big bang', the strength of the electromagnetic force. The basic point of this argument is that, if any of these constants were altered by a fraction of a percent, life in this universe would be impossible. So, how then do we explain this 'fine-tuning'? There is no physical, metaphysical or logical necessity for these fundamental constants had being this way; and the fine-tuning is far too improbable to be explained away as 'chance'. So, in the absence of chance and physical necessity as possible explanations, design is by far the most compelling explanation. This argument is strong precisely because such fine-tuning cannot (even potentially) be explained away as the by-product of Darwinian-like natural processes, as it is an example of specified complexity at the very foundations of physics. There is no room for evolution, Darwinian or otherwise. Instead, critics of the argument must appeal to such implausible, non-empirical postulates as the existence of a potentially infinite number of 'other universes' to explain away this improbability. However the multiverse idea has its own significant problems. Defenders of this argument include Robin Collins ('The Teleological Argument: An Exploration of the Fine-Tuning of the Universe'; 'The Fine-Tuning Argument: A Scientific Argument for the Existence of God'), William Lane Craig (Reasonable Faith: Christian Truth and Apologetics), and Richard Swinburne (The Existence of God, 2nd Edition), among others.

9. Aquinas' Third Way: The Argument Possibility and Necessity (Contingency  Argument). The third of Aquinas' famous 'Five Ways', this contingency argument originated with Islamic philosopher Avicenna (Ibn Sina) in the eleventh century A.D. (or C.E.). Like all Aquinas' cosmological arguments, the Third Way depends crucially on a fundamental metaphysical distinction: in this case the distinction between 'necessary' and 'possible' (or 'contingent') existence. The argument could be summarised as follows:

1. Some real things that we find have the possibility of being and not being.

2. But it is impossible that everything that exists should be such [or: it is impossible that all such things should always exist]: for that which has the possibility of not being at some time does not exist.

3. Therefore not all beings have this possibility: there must be something real which is necessary.

4. But everything which is necessary either owes its necessity to some cause outside it, or not.

5. There cannot be an infinite series of necessary beings whose necessity is caused.

6. We must suppose, then, something that is necessary in itself, which does not owe its necessity to some outside cause, but rather causes the necessity of the other things: and this is what all say is God.

This argument is regarded by most Thomistic scholars as the most fundamental of Aquinas' three cosmological arguments, as it focuses on the radical contingency of created beings, rather than just on certain aspects of reality (i.e., change and causation in the first two ways).

As Aquinas is easily the most studied of all medieval thinkers, numerous scholars have discussed this argument, alongside the other four of the Five Ways. The most in-depth studies include John Wippel's The Metaphysical Thought of Thomas Aquinas: From Finite Being to Uncreated Being, Edward Feser's Aquinas: A Beginner's Guide, C.F.J. Martin's Thomas Aquinas: God and Explanations, Dennis Bonnette's Aquinas' Proofs for God's Existence and Reginald Garrigou-Lagrange's God: His Existence and His Nature (Vol. 1).

Some study has also been done of Avicenna's version of the argument, including Jon McGinnis' Avicenna and his essay 'The Ultimate Why Question: Avicenna on Why There is Something Rather than Nothing' in The Ultimate Why Question, ed. by John Wippel.

8. The Argument from Order in Nature. This might be the oldest argument for the existence of God. Today, this argument might be called 'the argument from laws in nature' - a label that has its origins in early-modern thought, when talk about 'laws' in nature became commonplace in academia. Prior to this, it was more common to refer to 'order' or 'final causes' in nature, not 'laws'. Arguments from order are quite ancient, and can be found in rudimentary form in the writings of ancient Greek, Roman, Jewish and Christian writings. In large part, the shift in terminology in the early modern period reflected a shift in attitudes toward nature: specifically from the Aristotelian view of nature found in medieval Scholastic thought, to the mechanistic view of nature found in the thought of early modern thinkers such as Sir Isaac Newton, Rene Descartes, etc. Discussion of this argument has appeared in the writings of many influential thinkers, such as a Plato and Aristotle. It is stated clearly in the 'General Scholium' of Isaac Newton's Principia Mathematica and in Albert Einstein's various comments on his view of God (for details, see Max Jammer's Einstein on Religion or Chapter 17 of Walter Isaacson's Einstein: His Life and Universe). The fullest discussion of this argument can be found in John Foster's The Divine Lawmaker: Lectures on Induction, Laws of Nature, and the Existence of God.

7. The Argument from Reason. This argument is, perhaps, the most misunderstood (or else ignored) in pop atheist literature. Interestingly, it is also widely ignored or misunderstood in more scholarly atheist literature. Simply put, this argument claims that a naturalistic worldview is self-defeating, because if reality (and everything in it) is the product of blind, irrational processes, then such processes (especially Darwinian processes) cannot account for the reliability of human reason. As Victor Reppert puts it, the argument "attempts to show that the necessary conditions of logical and mathematical reasoning, which undergird the natural sciences as a human activity, require the rejection of all broadly materialist worldviews." The upshot of this argument is that, if naturalism (and atheism) were true, it would effectively undermine the reasonableness of our confidence in the general reliability of human reason. As all rational argument presupposes the capacity of human beings to reason to the truth, if we accept the central importance of reason, we must reject all worldviews that are incompatible with this presupposition. One of the earliest proponents of this argument was probably Arthur James Balfour in his Theism and Humanism, though the basic ideas behind the argument can be found in the writings of Alfred Russel Wallace. The argument was repeated by C.S. Lewis in Miracles and by Victor Reppert in C.S. Lewis' Dangerous Idea: The Argument from Reason, as well as various articles (see here and here). A somewhat different version of this argument has been defended by Alvin Plantinga as the 'Evolutionary Argument Against Naturalism', rather than as an argument for theism, in Where the Conflict Really Lies: Science, Religion & Naturalism.

6. The Kalam Cosmological Argument. This argument finds it origins in the writings of late antique Christian philosopher and scientist John Philoponus, specifically his critiques of the arguments of Aristotle and Proclus for an eternal universe. It was developed into a fully-fledged theistic argument by early Medieval Islamic philosophers al-Kindi and al-Ghazahli, who adopted and adapted several of Philoponus' arguments. The argument has been revived in recent decades by Christian philosopher William Lane Craig. Other philosophers such as David S. Oderberg, J.P. Moreland, Robert Koons and Robert Spitzer have defended it, as well. The argument, in its contemporary form, puts forward four lines of argument for why the cosmos (i.e., material reality) cannot be past-eternal, and so must have a beginning and a cause of its existence that transcends to material reality. Two of these lines of argument are drawn from modern physics and cosmology; two are drawn from philosophy.

The argument can be summarised as follows:

1. Everything that begins to exist has a cause of its existence.

2. The universe (i.e., material reality) began the exist.

3. Therefore, the universe has a cause of its existence.

4. Nothing can be the cause of its own existence.

5. Therefore, the universe has a cause of its existence that transcends material reality.

After this, Craig proceeds to 'unpack' the concept of the First Cause of material reality, demonstrating that it must be: self-existent, immaterial, eternal, timeless, space-less, immensely powerful and intelligent. This somewhat skeletal summary of the argument can give the impression that it lacks detailed argument in support of its two key premises (1 & 2). However, Craig summarises the argument in this way for brevity only. The actual argument is far more detailed. The kalam argument is, perhaps, the most discussed version of the cosmological argument in contemporary philosophy of religion - by both theists and atheists. It is also the most distinctive, as it is the only version of the cosmological argument that argues for a beginning to the cosmos. Craig has discussed and defended the argument most fully in The Kalam Cosmological Argument, Reasonable Faith (see excerpt here) and his lengthy technical article 'The Kalam Cosmological Argument' (co-authored with James Sinclair).

5. Aquinas' Second Way: The Argument from Efficient Causation. Each of Aquinas' cosmological arguments focus on a particular, fundamental aspect of physical reality. The third way focuses on the contingency of physical things. The first way focuses on change or 'motion', as Aristotle calls it. The second way focuses on the reality of efficient causation. It can be summarised like this:

1. We find, in things around us that we sense, an order of efficient causes.

2. But we do not find — nor could there be — anything that is the efficient cause of itself.

3. It is not possible that there should be an infinite series of efficient causes.

4. Hence we must suppose some first efficient, uncaused cause, and this is what all call ‘God’.

This argument presupposes a number of key distinctions fundamental to Aquinas' metaphysics, such as the act/potency distinction, the distinction between accidentally- and essentially-ordered causal series and the distinction between being and essence. For a discussion of these, see Gaven Kerr's article 'Aquinas: Metaphysics'. It is also important to remember that Aquinas doesn't simply assert that such a 'First Cause' must be God, but spends a considerable amount of space in the Summa Theologiae and other writings unpacking this idea of a 'First Cause' to show that it must indeed be God. For a fuller discussion of the Second Way, see the books mentioned above in the section on the Third Way. Also, an excellent defence of this argument can be found in Edward Feser's Five Proofs of the Existence of God, Ch. 4.

4. The Neoplatonic Argument from 'the many' to 'the One' (i.e., God). This argument starts from the realisation that composite things (things made up of multiple parts) require an explanation for or cause of their existence, right here and now. Composite things cannot explain themselves, because they exist only because the things of which they are composed exist. I exist because am composed of various organs, that are, in turn, composed of various tissues, that are composed of various molecules, that are composed of various atoms, that are composed of various sub-atomic particles, and so on. But how do these things come together to form me? The same question could be applied to all material things. Ultimately, the existence of composite things can only be explained in terms of a 'first principle' that is not itself composed of anything, nor derives its existence from anything else. Interestingly, this argument blends together elements of both cosmological and teleological arguments. It is asking not only for the cause of existence (cosmological argument) but also the cause of order (teleological argument) - a 'theory of everything' you could say, except it is not a 'theory', but a metaphysically necessary explanation. As Edward Feser notes, one could refer to it as a 'teleo-cosmological argument'. Feser states this argument as follows:

1. There must be a first principle of all if there is to be an explanation of the orderly existing world, or why anything at all exists rather than nothing.

2. If the first principle of all were composed of parts, then those parts would be ontologically prior to it.

3. But in that case it would not be the first principle of all.

4. So the first principle is not composed of parts, but is absolutely simple.

5. If there were a distinction between what the first principle is and the fact that it is, then there could be more than one first principle.

6. But in order for there to be more than one, there would have to be some attribute that distinguished them.

7. But since a first principle is absolutely simple, there can be no such attribute.

8. So there cannot be more than one first principle.

9. So there is no distinction in the first principle between what it is and the fact that it is.

10. So the first principle is not only absolutely simple but utterly unique, what Plotinus called “the One.”

This "One" could not be a part of material reality, such as a law of nature, as laws of nature are merely descriptions of how physical things behave in certain situations. 'Laws' are derived from material things, material things are composite, composite things cannot be self-existent (for the reasons stated above), therefore "the One" cannot be a material being. Nor could appealing to the sum-total of material beings (the universe or multiverse) explain anything, because the universe (or multiverse) would be composite, as well. "The One", therefore, is an immaterial, non-composite (i.e., simple), self-existent, unique, eternal being that causes everything (except itself) to exist. And this, as Aquinas would say, is what everyone understands to be God.

This argument was first developed in Plotinus' Enneads. However, similar lines of reasoning can later be found in certain Scholastic writings, such as Thomas Aquinas' discussion of divine simplicity in the Summa Theologiae. Contemporary discussions of this argument are few, but include Lloyd Gerson's Plotinus and his essay 'Neoplatonism' in The Blackwell Guide to Ancient Philosophy.

3. The Contingency Argument (Modern Versions). From the Medieval Period to the Early Modern Period, the use of the key terms 'necessary' and 'contingent' changed in subtle, but highly significant ways, in large part due to the shift away from Aristotelianism toward rationalism and other early modern philosophies. Consequently, the contingency argument also changed, so that the rationalist versions of this argument differ crucially from the version found in Aquinas. In the early modern period there were several major defenders of the contingency argument, most notably Rene Descartes in his Meditations on First Philosophy, Gottfried Leibniz in his Monadology and Samuel Clarke in his A Demonstration of the Being and Attributes of God. One of the foremost contemporary defenders of the contingency argument is Alexander Pruss in his book The Principle of Sufficient Reason: A Reassessment and his article 'The Leibnizian Cosmological Argument'. Pruss summarises the Leibnizian argument this way:

1. Every contingent fact has an explanation.

2. There is a contingent fact that includes all other contingent facts.

3. Therefore, there is an explanation of this fact.

4. This explanation must involve a necessary being.

5. This necessary being is God.

Some contemporary defenders of this argument would not talk of 'contingent facts' but 'contingent beings/things', modifying Premise 1 from 'Every contingent fact has an explanation' to 'Every contingent thing has an explanation of its existence', or something similar - adopting an understanding of 'contingency' that is somewhere in between those of Aquinas and Leibniz. For example, Bruce Reichenbach proposes this formulation of the argument:

 1. A contingent being (a being such that if it exists, it could have not-existed or could cease to exist) exists.

2. This contingent being has a cause of (or explanation for) its existence.

3. The cause of (or explanation for) its existence is something other than the contingent being itself.

4. What causes (or explains) the existence of this contingent being must either be solely other contingent beings or include a non-contingent (necessary) being.

5. Contingent beings alone cannot provide a completely adequate causal account (or explanation for) the existence of a contingent being.

6. Therefore, what causes (or explains) the existence of this contingent being must include a non-contingent (necessary) being.

7. Therefore, a necessary being (a being such that if it exists, it cannot not-exist) exists.

8. The universe is contingent.

9. Therefore, the necessary being is something other than the universe.

Not surprisingly, this argument, as stated - like all the arguments summarised here - requires a lot more explanation and argument to demonstrate its validity. Nonetheless, once you take the time to understand the argument properly, it is quite compelling.

2. Aquinas' Fifth Way: The Argument from Final Causality. Aquinas' argument can be summarised as follows:

1. We see that there are things that have no knowledge, like physical bodies, but which act for the sake of an end.

2. But things which have no knowledge do not have a tendency toward an end unless they are directed by something that does have knowledge and understanding.

3. Therefore there is some being with understanding which directs all things to their end, and this, we say, is God.

This argument, in certain respects, is akin to the 'Argument from Order' listed above. Where it differs - quite significantly - is in the metaphysical background to the argument. Aquinas' argument is rooted in Aristotle's idea of 'final causality', i.e., the idea that all things are naturally oriented towards certain ends, e.g., all objects of mass are naturally oriented towards a center of mass - which is why things on earth fall towards the earth's center. For the Aristotelian, teleology - or final causality - is fundamental to the very cause-effect nature of reality. The reason that causation in nature follows regular, intelligible patterns is because all things have natures, and those natures are oriented towards certain ends. For early moderns, by contrast, material objects are not naturally oriented towards certain ends. Nature is devoid of all intrinsic teleology. Instead, order is imposed upon material reality by God. This order, early moderns called 'laws of nature'. This distinction between intrinsic and extrinsic teleology is at the heart of the distinction between Aquinas' 'Argument from Order' and the early moderns' 'Argument from Order'. Defenses of the Fifth Way can be found in the resources listed above in the section on the Third Way. For a more in-depth discussion and defence of the Aristotelian idea of final causality see David S. Oderberg's articles 'Finality Revived: Powers and Intentionality' and 'Teleology: Organic and Inorganic'. See, also, Edward Feser's article 'Teleology: A Shopper's Guide' and 'From Aristotle to John Searle and Back Again: Formal Causes, Teleology and Computation in Nature'.

Honourable Mentions:

• The Moral Argument

Quality discussions of this argument can be found in W.R. Sorley's Moral Values and the Idea of God, William Lane Craig's book Reasonable Faith and article 'The Indispensability of Theological Meta-Ethical Foundations for Morality', and Mark Linville's 'The Moral Argument'.

• The Argument from Consciousness

This argument has been carefully defended by J.P. Moreland in Consciousness and the Existence of God: A Theistic Argument.

• Aquinas' Fourth Way: The Argument from Degrees of Perfection

See resources listed above in the section on the Third Way.

• Bernard Lonergan's Proof of Unconditioned Reality

First discussed by twentieth-century philosopher Bernard Lonergan in his Insight: A Study of Human Understanding (Chapter 17) and defended by Robert Spitzer in New Proofs for the Existence of God: Contributions of Contemporary Physics and Philosophy (Chapter 4). This argument is similar, in one key respect, to versions of the cosmological argument - e.g., the contingency argument (No. 3, above) - in that it argues that, if reality it to have any explanation at all, that explanation must be a self-existent being (or 'Unconditioned Reality'), i.e., God.

And now...

1. Aquinas' First Way: The Aristotelian Argument from Motion/Change. This argument focuses on the reality of change or 'motion' in the world. Change is one of the most fundamental and obvious aspects of physical reality, which is why Aquinas regards the First Way as being the 'most obvious' of all his proofs. Today, the argument may not seem quite as persuasive as it was in Aquinas' time, due partly to the re-conception of 'motion' in Newtonian physics, but Aquinas is speaking of 'motion' in a much broader sense than Newtonian physics, based on Aristotle's description of 'motion' or change as the reduction of potency (or potential being) to act (or actual being).

The First Way can be summarised as follows:

1. It is certain — it is obvious to the senses — that in this world some things are in the process of change.

2. But everything that is in the process of change has that change initiated in it by something else.

3. But if that which initiates the change is itself in the process of change, then it too must have its change initiated by something else: and so on.

4. We cannot go on to infinity in this line,

5. So we have to come to some first initiator of change which is not in a process of change initiated by something else, and everyone understands that this is God.

Like the Second Way (see above), the First Way depends on certain fundamental distinctions in Aquinas' metaphysics, i.e., the distinction between act and potency and the distinction between accidentally- and essentially-ordered causal series. The most in-depth and up-to-date defences of these distinctions  and how they can be applied to reality can be found in Edward Feser's Scholastic Metaphysics: A Contemporary Introduction and David S. Oderberg's Real Essentialism. For a slightly older and very long (but free) discussion of Thomistic philosophy see R.P. Phillips' Modern Thomistic Philosophy, Volumes 1 and 2. Defenses of the First Way can also be found in the works listed above in the section on the Third Way.