Cosmological arguments attempt to justify the conclusion that God exists as the required explanation of the existence of the universe.
A posteriori. Cosmological arguments are typically a posteriori arguments, which means they are based on experience. The cosmological argument is based on observation of everything in the universe having a cause, being in motion or being contingent and therefore requiring a creator. These observations form the premises of cosmological arguments. On the basis of those observations, an inference is then made to the nature of the origin of the universe being God.
Cosmological arguments from causation
Aquinas’ first and second ways
Aquinas’ first two ways are developed from Aristotle’s theory of efficient causation, which is an attempt to explain the change we observe. Aristotle thought that change required a prime mover which sustains the motion and causation we experience.
Efficient causation involves sustaining causes, those which bring about their effect continuously, such that if they ceased to exist then their effect would also cease to exist. E.g., the gravity of the earth causes the moon to be in orbit, which in turn causes the sea tides to rise and fall on earth.
Aquinas’ 1st way (motion)
P1. We observe that there are things in motion.
P2. Motion is the actualization of a thing’s potential to be in motion.
P3. A thing can only come to be in motion by being moved.
P4. A mover must be something that is actual, i.e., in a state of actuality.
P5. A thing cannot move itself.
C1. So, all things in motion must have been moved by a mover, which was also moved by another mover.
P6. There cannot be an infinite regress of movers, otherwise there would be no first mover and then no motion.
C2. Therefore, there must be a first mover which must itself be unmoved (as it is pure actuality). That thing we call God.
Change requires going from potential to actual, which depends on something that is actual, which cannot depend merely on other potential things, so there must be something of pure actuality. A thing that is purely actual with no potential cannot change, it is an unmoved mover or uncaused causer.
Aquinas’ 2nd way (atemporal causation)
P1. We observe efficient causation.
P2. Nothing can cause itself.
P3. There is a logical order to sustaining causes: the first cause, then intermediate causes, then an ultimate effect.
P4. If A is the efficient cause of B, then if A doesn’t exist neither does B.
C1. There must be a first sustaining cause, otherwise P1 would be false as there would be no further sustaining causes or effects.
C2. As there is a first cause, there cannot be an infinite regress of causes.
C3. The first cause must itself be uncaused. That thing we call God.
Aquinas’ first two ways treat the relationship between cause and effect as ontologically real but not temporal, although they are consistent with a temporal understanding of cause and effect. They point to the logical implications of there being sustaining causes. This is why especially Aquinas’ 2nd way is called a cosmological argument from ‘atemporal causation’.
The first and second way attempt to show God must exist as the first mover or causer. The word ‘first’ in the concept of a first cause or first mover is not meant to indicate it being ‘first’ in time, but ontologically first in the sense that motion and causation are ontologically dependent on it.
The Kalam cosmological argument from temporal causation
The Kalam cosmological argument explicitly involves temporal causation, which is when a cause brings about its effect after it and the continued existence of the effect is independent of the existence of the cause.
The Kalam infers a beginning cause rather than a sustaining cause. The causal sequence being temporal, with God as the beginning cause, is a central feature of the argument.
One advantage of the Kalam argument is that it’s easier to explain how an atemporal God could create the world in one act compared to a sustained act of creation over time.
W. L. Craig brought this argument to prominence in the late 20th century and named it ‘Kalam’ after the Islamic philosophy which first invented in the 11th century.
P1. Everything that begins to exist has a cause of its existence.
P2. The universe began to exist (an infinite regress is not possible).
C1. So, the universe has a cause of its existence.
Further steps are required to show that the cause of the universe is God. Craig firstly argues that scientific explanation applies within the universe and therefore cannot apply to its actual creation. The cause of the universe must therefore have a personal explanation, i.e., intentionally created by an intelligent mind. This being must have the power to create a universe from nothing (ex nihilo). It must be outside time and space since it created time and space. As a timeless, eternal being, God did didn’t begin to exist so it’s then no contradiction in claiming that God doesn’t have a cause. These are qualities that God would have, so the cause of the universe is God.
A strength of the Kalam argument is W. L. Craig’s arguments for the impossibility of an ‘actual infinite’ meaning an infinite in reality. The problem is that sets with infinite members can be equal in size to their subsets. Craig uses the illustration of a library with an infinite number of books, half of which are red. Half of infinity is still infinity, so half of infinity is not actually smaller than infinity. This might make sense theoretically, but Craig claims problems arise when applying it to reality. It would mean the set of red books ‘X’ is apparently smaller than the set of all the books ‘Z’, and yet paradoxically is also equal in size, since both are infinite. Infinities therefore cannot actually exist, since then they could be both smaller than and the same size as other infinities.
Counter: An infinite series is actually possible.
G. Cantor argued that the mathematical properties of infinite sets/things are simply radically different to those that are finite, making Craig’s library or Hilbert’s Hotel not absurd. Craig takes it to be obviously absurd for a subset (red books) to be both smaller than and equal to its set (all the books). However, it’s only absurd for finite sets. For infinite sets it’s not absurd, it’s actually their defining characteristic. When we think of libraries or hotels, we have in mind our ideas about finite sets of things, but Cantor argued such intuitions are not applicable to infinite sets. Infinite sets simply have different mathematical properties, one of which is the possibility of a one-to-one relation between the number of members of infinite sets and those of their subsets.
Hume’s objection to the ‘causal principle’
The strength of cosmological arguments from causation is that they are based on the causal principle, which is that every event has a cause, or that every contingent being has a cause of its existence.
Ex nihilo nihil fit (nothing comes from nothing) goes back to the ancient Greeks like Parmenides who influenced Aristotle and later Aquinas. It’s not possible for an event to happen without a cause, otherwise something could come from nothing, which is absurd.
Arguing for the Kalam cosmological argument, William Lane Craig claims that the causal principle is:
“based on the metaphysical intuition that something cannot come out of nothing.” – W, L. Craig
A causal principle is one of the essential pillars of cosmological arguments, alongside arguments against the possibility of infinite regression and inferences to the divine nature of the ultimate origin of the universe.
Weakness: Hume’s objection to the causal principle.
Hume’s fork tells us that propositions (such as the causal principle) can either be analytic or synthetic.
Hume argues that the causal principle is not true by definition (analytic). There doesn’t appear to be anything incoherent in the idea of an event or thing existing without a cause. It is conceivable and not obviously self-contradictory. We can imagine something popping into existence without a cause. The idea of a four-sided triangle is obviously self-contradictory because the idea of triangle contradicts the idea of four-sides. Yet, the idea of an event doesn’t seem contradicted by the idea of no cause.
So, the causal principle can only be justified on a posteriori grounds, which makes it a synthetic truth. The problem is, claims based on experience cannot be known with certainty to be true in all cases. All we can justifiably claim is that every event we have observed has a cause. It does not follow from this that all events have a cause, since we have not experienced all events.
So, the universe could exist without a cause. The cosmological argument therefore fails because in attempting to argue for God’s existence as the required explanation of the universe, it assumes that the universe has a cause.
Lawrence Krauss & Alan Guth add evidence from modern theoretical physics which resonates with Hume’s point. The universe has zero total energy and therefore required no energy to be created So, it could have come from nothing.
Evaluation defending the cosmological argument:
The cosmological argument could be defended by arguing that the universality of the causal principle is justified through induction. We have experienced many causal interactions, all of which involved the constant conjunction of cause and effect. From this we can infer that all effects have a cause. It is possible that this may be false, that in some cases the causal principle may not hold. However, the evidence so far suggests that it always holds. Therefore, we are empirically justified in accepting the causal principle.
Evaluation criticizing the cosmological argument:
Furthermore, we cannot even be empirically justified in holding the causal principle. All the evidence that we have for the causal principle comes from our observation of change within the universe itself. We are not justified in assuming the relevance of that experience to the conditions under which the universe itself came to exist. Those conditions, whatever they are, could be radically different to anything we now observe within the universe. So, we cannot even justify the causal principle on an empirical basis.
Cosmological arguments from contingency
Aquinas’ 3rd way (contingency)
P1. We observe that there are contingent beings.
P2. A series of contingent beings cannot regress infinitely into the past.
C1. So, a series of contingent beings must be finite.
P3. If this finite series was all that existed, then before it would be nothing.
P4. If there was once nothing, there would be nothing now, which is absurd.
C1. So, there must be more than this finite series of contingent beings, i.e., a necessary being.
P5. There cannot be an infinite regress of necessary beings.
C3. There must be a necessary being “having of itself its own necessity … That thing we call God.”
Leibniz’ principle of sufficient reason
Leibniz improves on Aquinas’ 3rd way by removing unnecessary reasoning about nothing once existing.
Leibniz’ argument is a priori, it doesn’t require inference from experience. The downside of a posteriori arguments is that they are defeasible, meaning in principle future experiences could always prove them false. A priori arguments based on logic are stronger.
Leibniz bases his argument on the principle of sufficient reason, which does both the job of a causal principle and an argument against the infinite regress. It shows that there must be not just any causal explanation, but a causal explanation which provides an ultimately sufficient reason for everything that exists. This strengthens the argument by making it dependent on only one claim.
P1. For every true fact or assertion, there is a “sufficient reason why it is thus and not otherwise.”
P2. There are two types of truth: truths of reasoning and truths of fact.
P2a. Truths of reasoning are necessary, so their opposite is impossible. The sufficient reason for truths of reasoning can be discovered a priori.
P2b. Truths of fact are contingent, so their opposite is possible. The sufficient reason for truths of fact cannot be discovered through other contingent truths, because they too require a sufficient explanation, and so on.
C1. A sufficient reason for contingent facts must be found outside a series of contingent things.
C2. The sufficient reason for contingent facts must be a necessary substance.
C3. That necessary substance is God.
C4. So, God exists.
Leibniz claims that the principle of sufficient reason (P1) can be known as a necessary truth. Even if we can’t know or even find out what the reason is, there must be one. ‘From nothing, nothing comes’ because nothing is not sufficient to create something. Only a necessary being is sufficient to explain the universe because otherwise there would be an infinite chain of contingent beings, but an infinite regress alone can have no sufficient explanation.
If things have always existed going back forever then nothing would have a sufficient reason for its existence. Everything’s reason for existence would consist something for which its reason for existence consists in something else. There would simply be an infinite deferring of the reason for existence and thus there would not actually be a reason for existence. So, a necessary being must have begun the chain of contingent beings and is the sufficient explanation of the universe.
The fallacy of composition
The strength of cosmological arguments from contingency is their seeking an ultimate explanation rather than only a first cause.
They focus more fundamentally on the nature of things. Beings have causal relations, but also an ontological status, i.e., contingency or necessity. Contingent beings & series must have an external explanation since it is their nature to depend on something else for their existence.
Weakness: Hume & Russell on the fallacy of composition.
This criticism explicitly attacks cosmological arguments from contingency, but if successful would also undermine arguments from causation. It is a fallacy to assume that what is true of a thing’s part(s) must also be true of the whole. Bertrand Russell illustrated this by pointing out that just because every human (parts) has a mother, that doesn’t mean the human race (whole) has a mother.
Hume uses the example of a finite set of contingent beings (20 particles). Just because the parts of a set/series of contingent beings have an explanation, that doesn’t mean the whole set/series has an explanation.
Experience shows that parts of the universe are contingent & have a cause/explanation. This doesn’t mean the universe itself as a whole must also be contingent (have a cause/explanation).
The only empirical way to believe a whole series has an explanation is to commit the fallacy of composition by assuming the whole is like the parts. So, a posteriori cosmological arguments commit the fallacy of composition by assuming that the universe has a cause when all we experience is that parts of the universe have a cause. That’s the problem with Aquinas’ 3rd way.
Evaluation defending the cosmological argument
However, Copleston rightly points out that contingency arguments don’t actually appear to make an inference from parts to whole.
They argue that a series of contingent things must have an external cause. Copleston argues:
P1. A series is either caused or uncaused.
P2. If a series is uncaused, the reason for its existence must be internal to it, making it necessary.
P3. No amount of contingent things can be necessary, not even an infinite number of them, so a series of contingent things cannot be necessary.
C1. So, a series of contingent things must have an external cause like a necessary being.
However, Hume’s empiricism drives his point further. Hume questions how we know a series must have a cause/explanation. In P2, Copleston assumes that an uncaused series must have an internal explanation. Hume doesn’t see how experience can justify thinking a series must have an explanation at all.
However, Leibniz’ a priori argument may avoid this problem as it’s derived from intuitively known a priori necessary truths, not experience. Leibniz is a rationalist and believes the whole has an explanation because of his a priori principle of sufficient reason. Nothing can be true, like a whole series existing, without a sufficient explanation for why it is thus and not otherwise.
Copleston vs Hume & Russell on the universe as a brute fact
Hume and Russell take the fallacy of composition objection further in a way that can respond to Leibniz’ a priori approach.
Hume turns to the example of an infinite series of contingent beings. He argues it is possible and doesn’t need an ultimate sufficient reason. Each being is explained by the being it depends on.
Of course, Leibniz wants to object that this leaves the whole chain itself without explanation, without reason for existence.
Hume, however, denies the validity of claiming that there is ‘whole’ chain. If experience only shows that contingent beings exist, we can question whether there actually is a ‘whole’.
“uniting of these parts into a whole, like the uniting of several distinct counties into one kingdom … is performed merely by an arbitrary act of the mind and has no influence on the nature of things.” – Hume
“I think the word “universe” is a handy word in some connections, but I don’t think it stands for anything that has a meaning … The whole concept of cause is one we derive from our observation of particular things; I see no reason whatsoever to suppose that the total has any cause whatsoever … it doesn’t need to be its own cause, what I’m saying is that the concept of cause is not applicable to the total.” – Russell.
We cannot say the ‘whole universe/series’ is even a valid concept, let alone that it is contingent. So, we can’t conclude there is a need for an explanation like a necessary being. Cosmological arguments from contingency fail. Note that this isn’t quite saying the universe could be necessary. A necessary being contains its own reason for existence, but Hume and Russell are proposing that the universe could simply have no explanation at all.
All we can justifiably say is that the universe/series is “just there, and that’s all” (Russell). It is a brute fact, one which has no explanation, whether causal or otherwise. Russell points to evidence from Quantum mechanics:
“The physicists assure us that individual quantum transitions in atoms have no cause.” – Russell.
So, arguments from contingency baselessly assume that a series (as a whole) must have an explanation at all.
This argument also counters the arguments from causation. If we have no basis for thinking the universe has an explanation of any kind, that includes causal explanation.
Evaluation defending the cosmological argument:
Copleston firstly responds that only some interpretations of quantum mechanics propose uncaused events. Copleston further argues:
“I cannot see how science could be conducted on any other assumption than that of order an intelligibility in nature” – Copleston.
Copleston’s argument is successful because the ‘brute fact’ argument is self-defeating. Science and philosophy are about finding out why things are the way they are; their causes and explanations. If we say that there is no reason, then we undermine the purpose of science and philosophy itself.
Evaluation criticizing the cosmological argument:
Furthermore, Russell argues that while a scientist may look for causes, they do not assume that there is one to find. Even if quantum transitions are only uncaused on some interpretations of quantum mechanics, the mere idea of it still shows that physicists are able to conceive of events that have no cause. It is therefore at least logically possible for events in nature to have no cause or explanation. So, a contingent series doesn’t need an external cause. The principle of sufficient reason cannot be a necessary truth. The universe could be one of those natural events that has no cause or explanation. Science should accept that possibility, since science should be open to whatever could be true.
Copleston attempts to show that Russell is assuming that there isn’t a cause and Russell attempts to show that Copleston is assuming that there is. Ultimately, defenders of the cosmological argument are the ones making the positive claim about reality, so they have the burden of proof. It looks like for cosmological arguments from contingency, the conclusion that God exists as the explanation/cause of the universe cannot be reached without assuming that the universe has an explanation/cause. In that case, the mere possibility of the universe being a brute fact is enough to undermine the cosmological argument. It’s not irrational to look for a cause, even a cause like a God, but since there might not be a cause it is irrational to think that there must be one.
Issues around the possibility of a ‘necessary being’
A strength of cosmological arguments from contingency is that their conclusions achieve more than arguments from causation. They can establish God’s necessity, meaning inability to cease existing, which is a key element of Christian theology. Aquinas understands necessity to mean the inability to cease existing, which fits with the concept of omnipotence.
Weakness: Hume’s rejection of the possibility of a necessary being.
Hume’s fork:
A priori reasoning can only tell us about the relations between ideas, i.e. analytic knowledge (true by definition). E.g. “a bachelor is an unmarried man”.
A posteriori reasoning can only tell us about matters of fact, i.e. synthetic knowledge (true by the way the world is). E.g. “The sun will rise tomorrow”.
“there is an evident absurdity in pretending to demonstrate a matter of fact, or to prove it by any arguments a priori” – Hume.
A being whose existence is logically necessary is an absurdity to Hume. A thing’s existence is a matter of fact. All matters of fact can be conceived false and denied without contradiction. So, anything which could exist could also not exist. The concept of a being which ‘must’ exist, whose existence cannot be denied without contradiction, is therefore absurd and meaningless.
Hume’s justification for the fork is that truths of logic/definition are necessary, because they will be true no matter what happens regarding the factual state of the universe. E.g., 1+1 will always = 2, because there is no possible change to the universe which could make it false.
This shows there is a disconnect between logical (analytic) truths which are necessary (cannot be otherwise) and factual (synthetic) truths which can. The term “necessary existence” violates this disconnect. It is about what factually exists, so must be synthetic. Yet, it somehow also has the “cannot be otherwise” property that only belongs to logical analytic truths. We cannot know that a being’s existence is logically necessary, since a being’s existence cannot be established through logic.
“The words, therefore, necessary existence, have no meaning.” – Hume.
Any argument which attempts to conclude that God exists necessarily therefore fails, including the ontological argument and some cosmological arguments.
Evaluation defending the cosmological argument:
The masked man fallacy. Hume’s argument depends on conceivability entailing possibility. It is therefore susceptible to the masked man fallacy, which shows that we can conceive of the impossible. Imagine someone heard of a masked man robbing a bank. They can conceived that it is not their father. Yet, if it was their father, then it is impossible that it is not their father. Yet, that was what they conceived of. So, we can conceive of the impossible. When Hume argues that our ability to conceive of God not existing shows that it is possible for God to not exist and that God therefore cannot be necessary, he assumes that conceivability entails possibility. Conceiving of God’s non-existence could be conceiving of something impossible because God is necessary.
Evaluation criticizing the cosmological argument:
Hume’s argument is successful because it is epistemological, i.e., focused on what we can know. Hume isn’t really saying a necessary being is ‘impossible’, just that it is impossible for us to know that such a being exists. Aquinas, Leibniz and Craig say that it is a being with the property of the impossibility of non-existence, but Hume simply throws up his hands and says he cannot see how anyone can ascribe meaning to that statement. We might technically be able to understand the words, but we cannot conceive or understand how they could map onto reality. If we are to accept the term on that basis, Hume rightly goes on to say that we might as well say that, even though we can’t understand how, reality itself has this mysterious property of the impossibility of non-existence, so positing a God is unnecessary anyway.
Issues around the possibility of an infinite series
A crucial strength of all cosmological arguments are the justifications its proponents provide for the premise that an infinite series is impossible. This is essential, for if there is an infinite regress going back in time forever then all forms of the cosmological argument fail. God could not be concluded to exist as the origin of what exists if there was no origin. These arguments attempt to show that the idea of an infinite regress leads to paradox or absurdity and therefore must be false.
Aquinas argues an infinite regress is impossible. If there was an infinite regress, there would be an infinite amount of time before the present moment. That means to get to the present moment, an infinite amount of time must have passed. However, an infinite amount of time cannot pass. No matter how long you wait, even if you never stop waiting, the amount of time passed can never reach infinity. So, there cannot be an infinite amount of time before the present moment and therefore there cannot be an infinite regress. You cannot traverse an infinite through successive addition.
Weakness: The possibility of an infinite series.
The idea of an infinite regress may be difficult to comprehend, but there is no obvious logical contradiction in the idea. The concept of ‘time’ does not seem contradicted by the predicate of ‘infinitely regressing into the past’.
Critics of the infinite regress attempt to show that while there is no obvious contradiction, nonetheless paradoxes arise from the concept. This aims to show that it is illogical and therefore impossible.
However, Hume thinks we simply lack the evidence on which to properly judge whether it is possible or not. We can strengthen Hume’s point with modern science which is full of examples where physicists speculate about ways an infinite regress could exist without paradox.
Some physicists argue for the block universe, that the passing of time is an illusion. Others suggest the universe eternally cycles between expansion and collapse and that a new timeline begins each cycle. In that case, an infinite amount of time never passes (so Aquinas fails) and in fact a time line containing an actual infinite never existed (so Craig fails). Yet, an infinite series of cycles happened (just not on any particular time-line).
The meta point of these examples is that we know very little about what time and infinity are and how they work, so claims about the impossibility of an infinite series are unjustified. Philosophers who think they can draw conclusions about time through pure logic alone fail because our actual concept of time is so poorly scientifically understood and could bare very little relation to what time actually is. It seems Hume would say we should admit that we are not in a position to conclude either that there is or is not an infinite regress.
Evaluation defending the cosmological argument:
There is certainly much we don’t know about time and infinity. However, what we currently understand suggests Aquinas’ reasoning is right. The eternal bang/crunch model may be logically possible, but we have no reason to believe it. The evidence suggests the universe started with a big bang and there is no evidence it will collapse again. We are justified in believing what we currently have most reason to believe.
Evaluation criticizing the cosmological argument:
Hume’s stance is the right one. We simply lack the required evidence to have a reasonable belief one way or the other regarding whether time regresses infinitely or not. Ultimately it is a matter for scientists and mathematicians and since they are far from decided, we are not justified in claiming an infinite regress is possible or impossible. Cosmological arguments therefore fail as they have the burden of proof. They are making a positive claim about what exists on the assumption of an infinite regress’ impossibility.
Extra credit:
Modern science’s rejection of the cosmological argument
A reasonably popular view in physics had been the steady state theory, which was that the universe had always existed and that there is a continuous creation of matter which expands. However in the mid 20th century, the discovery of the microwave background radiation provided very strong evidence against steady state and for the big bang theory. Steady state theory leaves no room for a creator God because it claims the universe was not created but has always existed, whereas the big bang arguably does leave room for God because the big bang could simply be how God created the universe. So, the big bang theory was actually welcomed by many Christians for this reason.
Pope Pius XII declared in 1951 that the big bang theory does not conflict with the Catholic conception of creation.
The question then becomes whether science can explain why the big bang happened without God. One possibility is the oscilating universe theory, that what we call our universe is just one of the cycles of big bangs and big crunches that has been oscilating forever.
However, another theory with more evidence for it is Alan Guth’s inflation theory. Laurence Krauss, a physicist, explains Guth’s theory that the universe came from nothing because it actually is nothing. Gravity has negative energy, the total amount of which in the universe happens to exactly cancel out the positive energy of the matter in the universe, so the total energy of the universe is zero; it is nothing. Krauss claims this answers Leibniz’ question of why there is something rather than nothing. Quantum mechanics has existed eternally and causes quantum fluctuations which can create a zero-energy universe from nothing because such a universe requires zero energy to create.
W. L. Craig’s response to Krauss is that Krauss’ definition of nothing is faulty since it’s actually something. Nothing really means total absence of anything.
Defence of Krauss: Arguably the definition of nothing philosophers have traditionally used is in fact not what nothing actually is though. Science has proven the philosophical conception of nothing to be inaccurate.