The Kalam argument (from temporal causation)
Aquinas’ 1st way (motion)
Aquinas’ 2nd way (atemporal causation)
Aquinas’ 3rd way (contingency)
Descartes’ argument based on his continuing existence (argument from causation)
Leibniz’s argument from the principle of sufficient reason (argument from contingency)
The possibility of an infinite series
Hume on the possibility of an infinite series. If there is an infinite regress of objects going back in time forever, then the cosmological argument fails because there would have been no first cause or mover. 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.
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. Every second you add is finite and can never total an infinite number of seconds. 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 for an infinite amount of time. Or, perhaps time is not even the sort of thing that actually passes and the passing of time is some kind of illusion that 4th dimensional beings experience. Perhaps time cannot be measured in numbers. The point is we know very little about how time works and Aquinas’ philosophical argument makes assumptions that science may one day contradict.
Hume’s objection to the ‘causal principle’
The fallacy of composition
Hume points out that it’s a fallacy to assume that properties of the parts of something must be properties of the whole. This is because it is possible for what’s true of the parts to not be true of the whole. If all you have knowledge of properties of the parts of a thing, you cannot infer from that alone that the whole also has those properties.
In the case of the universe, Aquinas rightly points out that all the parts of the universe have a cause and are contingent. However, it commits the fallacy of composition to assume that therefore the universe itself as a whole is contingent or must have a cause. 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.
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.
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.
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 that he’s not making the mistake of inferring a cause for the whole series from the fact that its members have a cause. He’s saying that a series of contingent things must have a transcendent 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. Russell responds that there is an assumption made by arguments from contingency. Copleston in P2 and Leibniz in P1 assumes that a series must have an explanation at all.
The claim (of Leibniz and Copleston) 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, the principle of sufficient reason cannot be a necessary truth. For all we know, the universe itself 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 in 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
“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.
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. Furthermore, they give us reason to think that this being does exist on the basis of a posteriori reasoning.