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.
The possibility of an infinite series
If there is an infinite regress of objects going back in time forever, then all forms of the the cosmological argument fail, because God could not be ultimately responsible for the origin of causation or the universe if it had no origin.
Hume points out that in order for something to be impossible it must be self-contradictory. For example, a four sided triangle is impossible because a triangle having four sides is contradicts the definition of a triangle as a three sided shape. However, there doesn’t appear to be anything self-contradictory about the infinite regress. Therefore it is possible and so the cosmological argument rests on an assumption that the infinite regress is false when it could possibly be true.
Craig responds that an actual infinity is impossible. He uses the illustration of a library with an infinite number of books, half red half green. If you were to take all the red books out of the library then you would have taken an infinite number of books out, but there would still be an infinite number left. This is because half of infinity still infinity. His claim is that this is just not how physical objects in reality could possibly function so it’s absurd to think that actual infinities could exist. Therefore, the infinite regress cannot exist.
The infinite library is a flawed analogy because it involves an example of an infinite number of physical objects, but an infinite regress could be a finite number of physical objects existing over an infinite amount of time. Craig has at most shown the absurdity of physical infinities but not temporal ones, which is what the infinite regress involves.
Aquinas claims an infinite regress is impossible because If there is an infinite regress, then time has existed forever. So there must be an infinite amount of time before the present moment. That means that 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, you will never actually reach infinity. So there cannot be an infinite amount of time before the present moment and therefore there cannot be an infinite regress. Modern Physicists think that time could have begun at the big bang, which would fit with Aquinas’ argument.
However, Physicists also have theories that suggest that the time which began at the big bang might only have been the time of our universe, and there could be other times or other kinds of time. The “big crunch” theory suggests that universes could have been eternally expanding and contracting again. If a new timeline began upon each contraction, an infinite amount of time would never pass even though the process of expansion and contraction has been going on infinitely. Or, perhaps time is not even the sort of thing that actually passes and the passing of time is some kind of illusion that beings of our dimensions experience. The point is we know very little about how time works and should not make assumptions about it, which the cosmological argument does.
The Kalam argument (from temporal causation)
The Kalam cosmological argument explicitly involves temporal causation, i.e., hypothesizing about the implications of events in time being related as cause and effect. It is looking for 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.
W. L. Craig brought this argument to prominence in the late 20th century and named it ‘Kalam’ after the Islamic philosophy under which it was 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.
Craig defends P2 by arguing that an actual infinity is impossible. He uses the illustration of a library with an infinite number of books, half red half green. If you were to take all the red books out of the library then you would have taken an infinite number of books out, but there would still be an infinite number left. This is because half of infinity still infinity. His claim is that this is just not how physical objects in reality could possibly function so it’s absurd to think that actual infinities could exist. Therefore, the infinite regress cannot exist.
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.
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. If something changes into something else, then it must have had the potential to change into that thing. Change is a thing’s potential becoming its new actual, and then it will have a new potential to change again. Aristotle thought that change required a prime mover which sustains the motion and causation we experience. Aquinas was interested in answering this question of why things continue to exist and change. Aquinas is concerned with sustaining causes, not temporal causes.
Temporal causation 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. E.g., the people who created the great pyramids of Egypt no longer exist, but the pyramids continue to exist.
A sustaining cause is one which brings about its effect continuously, such that if it ceased to exist then its 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 on earth, which cause the eroding of rocks on beaches.
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 Aquinas’ first and especially his 2nd way are called cosmological arguments 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.
Aquinas’ 1st way (motion)
P1. We observe that there are things in motion.
P2. Motion is the reduction of a thing’s potential to be in motion to actually being 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 sustaining causes.
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.
Hume’s objection to the ‘causal principle’
The causal principle is the claim that every event or thing has a cause.
The arguments of Descartes, the Kalam and Aquinas’ first and second ways all presume the causal principle is valid; that things which change or exist have a cause.
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.
Hume claims that our belief that two events are causally related results from our having observed them being constantly conjoined. Every time you have seen someone drop a ball (event A) it is followed by the ball dropping to the floor (event B). Hume urges that this is not enough to justify the belief in a necessary connection between event A and B, however. No matter how many times you observe one event following another, you cannot be justified in thinking there is a necessary connection between those two events such that it would be impossible for event A to happen without event B. No matter how many times we observe things which have a cause, we are not justified in thinking that all events have a cause.
In that case, we cannot justifiably claim that the causal principle applies universally. We do not know whether all effects have a cause. All we know is that the effects we have observed have a cause.
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.
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.
However, all the evidence that we have for the causal principle comes from our observation of change within the universe itself. Arguably 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.
Aquinas’ 3rd way (contingency)
P1. Everything is contingent
P2. There cannot be an infinite regress of contingent things
P3. Assuming P1, before a finite series of contingent things would be nothing.
P4. If there was once nothing, there would be nothing now, which is absurd
C1. P1 leads to an absurdity so it is false.
C2. There must be a necessary being.
C3. There cannot be an infinite regress of necessary beings
C4. There must be a necessary being “having of itself its own necessity … That thing we call God.”
The premise that everything is contingent leads to the absurd conclusion that nothing now exists. Since that is false, what led to it (that everything is contingent) must be false, so there must be a necessary being which started the whole process.
Leibniz’s argument from the principle of sufficient reason (argument from contingency)
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 P1, the principle of sufficient reason, 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 is not sufficient.
The key part of Leibniz’s argument for the purposes of the cosmological argument is that the reason must be ‘sufficient’. Leibniz argues that if things have always existed going back forever (infinite regress) then nothing would have a sufficient reason for its existence. This is because 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
It is a fallacy to assume that what is true of a thing’s part(s) must be true of the whole. It is possible for what’s true of the parts to not be true of the whole. If all you have knowledge of are properties of the parts of a thing, you cannot infer from that alone that the whole also has those properties. Bertrand Russell illustrated this by pointing out that just because every human has a mother, that doesn’t mean the human race has a mother.
In the case of the universe, Cosmological arguments rightly point out that the parts of the universe (at least those we have observed) have a cause or are contingent. However, it commits the fallacy of composition to assume that therefore the universe itself as a whole is contingent or has a cause.
Russell concludes that the universe is ‘just there, and that’s all’, i.e., it could exist without reason or cause or explanation. This has often referred to as the universe being a ‘brute fact’. It claims that due to the fallacy of composition, we have no basis for thinking that notions such as causation even apply to the universe. The universe could be necessary, in which case its explanation would be its necessary existence, or it could simply have no explanation.
Hume and Russell are not claiming to know that the universe has no cause or is not contingent. They are merely pointing out that it is invalid to argue from the parts of the universe having a cause to the universe itself as a whole having one. While the properties of the parts of something may possibly be the properties of the whole they aren’t necessarily so and it is the fallacy of composition to assume that they are.
This argument works best against cosmological arguments from contingency (Aquinas’ 3rd way & Leibniz’ PSR) because they assume that the universe as a whole is contingent. If the universe is not contingent then we don’t need God to explain its existence.
Aquinas’ 1st and 2nd way do not explicitly claim that the universe has a cause because its parts have a cause. They only argue that because we find motion and causation in the universe, their explanation must be an unmoved mover or uncaused causer.
One response is to try and argue that sometimes what is true of the parts is true of the whole, e.g., a brick wall. The bricks of a brick wall are made of brick, but so is the whole wall. In that case the parts are like the whole. The relation of the universe to its parts may be more like that brick wall to its bricks than the human race to its members.
However, while the universe and its parts might be like that of a brick wall to its bricks, it also might not! If not, then the cosmological argument fails.
Copleston responds to the fallacy of composition that arguments from contingency are not making the mistake of inferring a cause for the whole series from the fact that its members have a cause. The argument, going back to Leibniz, is that a series of contingent things must have an external cause. Copleston’s argument is as follows:
P1. A series is either caused or uncaused.
P2. If a series is uncaused, then the reason for its existence must be internal to it; its existence is necessary.
P3. A series of contingent things can’t be necessary. No amount of contingent things can be necessary, not even an infinite number of them.
C1. Therefore, a series of contingent things cannot be necessary.
C2. Therefore, a series of contingent things must have a cause.
C3. Therefore, there must be a cause of the series of contingent things which is outside the series.
Only 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.
Those which are a priori may avoid this problem by claiming to be derived from necessary truths rather than experience.
Russell’s brute fact response to the cosmological argument and Copleston. Russell responds that there is an assumption made by arguments from contingency. Copleston, Leibniz and Aquinas all assume that a series must have an explanation at all.
The claim that contingent beings or series of contingent beings must have a sufficient explanation could be denied without contradiction. It therefore cannot be a necessary truth. A series (whether finite or infinite) could have no cause/reason/explanation at all. Russell points to Quantum mechanics as evidence for his argument:
“The physicists assure us that individual quantum transitions in atoms have no cause.”
Copleston responds that only some interpretations of quantum mechanics propose uncaused events. Copleston insists that science and philosophy is about looking for causes and explanations.
“I cannot see how science could be conducted on any other assumption than that of order an intelligibility in nature” – Copleston.
However, Russell responds 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.
The impossibility of a necessary being
Cosmological arguments which conclude that a necessary being exists are vulnerable to this objection, e.g. Aquinas’ 3rd way and Leibniz’ principle of sufficient reason.
“there is an evident absurdity in pretending to demonstrate a matter of fact, or to prove it by any arguments a priori” – Hume.
A necessary being must exist – it cannot be the case that it does not exist. This means we shouldn’t even be able to conceive (imagine) it not existing, without contradiction. However, Hume claims that whatever we conceive of as existing, we can conceive of as not existing. There is no being whose non-existence implies a contradiction. Hume concludes:
“The words, therefore, necessary existence, have no meaning.”
This argument references “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”.
Whether a being exists is a matter of fact, so it cannot be established though a priori reasoning. Hume’s basis for the fork is that if a particular truth is a matter of logic/definition, then it will be true or false no matter the factual state of the universe. E.g., one plus one will always equal two, regardless of what happens to be factually true of the universe. This suggests there is a disconnect between logical truth and factual truth. The term “necessary existence” seems to ignore this disconnect. We cannot know that a being’s existence is logically necessary, since a being’s existence cannot be established through logic.
Any argument which attempts to conclude that God exists necessarily therefore fails, including the ontological argument and some cosmological arguments.
Masked man fallacy. Hume’s argument depends on conceivability entailing possibility. It is therefore succeptible to the masked man fallacy, which shows that we can concieve of the impossible. Imagine someone heard of a masked man robbing a bank. They can concieve 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 concieved of. So, we can concieve of the impossible. When Hume argues that our ability to concieve 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. Concieving of God’s non-existence could be concieving of something impossible because God is necessary.
Alternate response to Hume: Hume conflates logical necessity and metaphysical necessity. Hume characterises arguments for God’s necessity as claiming that ‘God exists’ is a necessarily true proposition. However, we could instead regard arguments for God’s necessary existence as claiming that “If God exists, God exists necessarily”. That is not attributing logical necessity to the truth of a proposition; it is attributing metaphysical necessity to a being. What makes God necessary is the metaphysical condition of a lack of dependence on anything else. It’s not necessarily true that such a being exists, but if it does, its existence is necessarily.
Hume’s fork: even if we take arguments for God involving necessity to be attributing necessity to a being, not to a proposition, the existence of that being still cannot be established by a priori reasoning. Matters of fact can only be inferred by a posteriori reasoning.
A posteriori cosmological arguments could survive this objection then. They give us reason to think that this being does exist on the basis of a posteriori reasoning.