a) Explain Hume’s criticisms of the cosmological argument. 
Hume’s criticisms of the cosmological argument are found in his book Dialogues on Natural Religion. In them Philo, Demea and Cleanthes discuss arguments for the existence of God. Hume was a sceptic and therefore doubtful about the claims of religion. The sceptic in the Dialogues called Philo has therefore been assumed to be putting forward Hume’s views.
The cosmological argument rests on certain principles of causation. In particular that any existent thing must have a cause or reason for its existence (this is what Leibniz points to in his principle of sufficient reason), and that there cannot be more in the effect than there is in the cause. Hume challenges these assumptions in his Dialogues.
There are three main categories of criticism that Hume makes of the argument. Firstly he has general concerns about the way it is structured, and believes that this structure is fallacious, secondly he has more specific concerns related to causation and finally he raises challenges to do with the concepts of contingency and necessity.
Hume’s challenges to the structure of the cosmological argument directly question the validity of the assumption that existent things need causes or reasons for their existence. Hume says that just because each of the elements of the ‘chain’ has a cause, it doesn’t follow that the chain itself needs a cause. He gives the example of a collection of twenty particles – if an explanation is found for each particle individually he says it would be wrong to then seek an explanation for the whole collection, because you have already explained it by explaining each particle. This is called the fallacy of composition, and was later memorably put by Russell that just because every man has a mother, it doesn’t mean that there is a mother of the human race.
Hume also says that people say the ‘whole’ needs a cause, but that the uniting of the parts into a whole is performed by an ‘arbitrary act of the mind’, in other words, what we call a ‘whole’ is only our own name for something that doesn’t actually exist ‘out there’. Eg. when we unite several counties into one kingdom, this has no influence on the nature of things, it is simply a human perception. So to look for a cause of this whole (arbitrarily defined by us) would seem to be mistaken. Modern physics would seem to provide some support for this – with the view of ‘pocket universes’ which exist within larger ones – to look for a ‘whole’ gets very difficult in this view.
Hume says that it is not inconceivable that the world had no cause, or just always existed – he says “it is neither intuitively or demonstratively certain” that every object that begins to exist owes its existence to a cause. He also says that like causes produce like effects – this seems to be true in the case of parent rabbits producing baby rabbits, for example, so as many things in the universe seem to be the offspring of two parents, why should we assume that there is one male ‘parent’ of the universe – wouldn’t it make more sense to postulate a male and female creator God?
Hume also has some challenges to the notion of causation, which the cosmological argument relies heavily on. In the Dialogues Demea puts forward an analogy of a house needing an architect – likewise the existence of an ordered universe requires a divine architect. Philo attacks this by saying that we while we experience houses coming from architects, we have no parallel experience with regard to the universe:
“When two species of objects have always been observed to be conjoined together, I can infer, by custom, the existence of one, where-ever I see the existence of the other… But how this argument can have place, where the objects, as in the present case, are … without parallel…may be difficult to explain.”
So we have had experience of houses coming from architects but no experience of the origins of universes, so we are in no position to talk about them. Hume had developed a theory of causation that was based on our epistemological limits as human beings – to talk about the origin of the universe is to go beyond the scope of human understanding and observation, as it is impossibly remote and unavailable to us. The empirical method is based on the ability to make observations to explain the causes of things. This is only possible for particular effects in the universe.
This is related to another problem that he identified with the notion of causation – that it is a ‘habit of mind’ rather than something that exists independently ‘within’ the object. He gives the example of a billiard ball hitting another – all we can observe is that the motion of one ball follows the motion of the other ball – we link the two in our minds and say that one causes the other to move, but there is no evidence of a link. Therefore, to base an argument on causation would be foolish, as we could never be sure that causation is anything other than a psychological effect. In fact it would be even more foolish in the case of the universe, because lacking past experience of formation of universes, we haven’t even got anything to base our ‘habit of mind’ on.
Finally Hume attacks the idea of a necessary being – these challenges relate specifically to Aquinas’ third way, as it relies on the notions of contingency and necessity.
Hume wonders if those qualities that make God’s non-existence impossible – couldn’t they belong to the universe itself? In other words why posit a necessary being rather than a necessary universe?
There is a deeper problem with the idea of a necessary being too. Any being that exists can also not exist, and there is no contradiction implied in conceiving its non-existence, but this is exactly what would have to be the case, if its existence were necessary. So the term ‘necessary being’ makes no sense a posteriori – any being claimed to exist may or may not exist. In Hume’s own words “All existential propositions are synthetic.”