A friend of mine expresses his doubts about whether something eternal can have a cause. The two predicates seem to him to be mutually exclusive such that to be eternal would seem to straightforwardly entail being uncaused. So, on this view, if x is not caused then x is simply eternal and, contra-positively, if x is not eternal then x is caused.
I think this view involves a misconception (wahm) and so what follows is my attempt to alleviate some of his worries. But first, a brief clarificatory note:
The concept ‘eternal’ in this context concerns duration of existence: x is eternal means x has always existed. And one way to explicate ‘always existing’ is in terms of a denial of x having been ‘non-existent’, i.e., ‘x is eternal’ can then be understood as the claim that ‘it is not the case that x did not exist at some time’. The claim that x is not eternal is just the negation of this. To sum up: for x to be not eternal is for it to be preceded by non-existence; and for it to be eternal is for it to not be preceded by non-existence. The precedence here is temporal. Call this thing – whose existence is preceded by non-existence (at some time t in the past) – a muhdath, i.e., temporally originated (thing).
Now, given the above, what is the relation all this to the notion of causality? It is this: the proponent of the view that nothing eternal can be caused, it turns out, is committed to the proposition that for x to be caused is for x to be a muhdath i.e., proceeded by non-existence. And this – the fact of it having been non-existent at some time – is what is ultimately explanatory of its being a thing that is caused. If this is the case, then it makes perfect sense why anything that isn’t a muhdath i.e., eternal, is eo ipso not caused.
Take the muhdath and consider its property ‘proceeded by non-existence’ (huduth).
If huduth explained the need for a cause, it would be prior to its subject
But properties cannot be prior to their subjects
Proof of the major: causes are prior to their effects. Proof of the minor: huduth, by definition, is that x’s existence is preceded by its non-existence. From this definition it follows that this property of x is posterior to the existence of x. That is, to hold that this thing x has the property of being a muhdath presupposes that it already exists right now; for nothing that is non-existent can bear the property of ‘being preceded by non-existence’.
(1) nothing —-> (2) existence of x —-> (3) property of huduth (of x)
Now, given that the property of huduth is the last link in the chain, it evidently cannot be the explanatory terminus of why x is caused. For if it were, it would be prior to itself i.e., it would exist as a property before the thing of which it is a property, i.e., x, itself actually exists. But this is absurd. Therefore, ‘being preceded by non-existence’ or, in other words, not being eternal, is not what explains being caused. That is, it is not the case that for x to be caused is for it to be a muhdath.
What the above considerations show, I hope, is that it is possible for a thing that is eternal, i.e., not preceded by non-existence, to be caused on the basis of showing that not being eternal, i.e., being preceded by non-existence, is not what explains being caused.