Samuel Clarke was a libertarian who strongly opposed the atheistic materialism popularized by Thomas Hobbes a generation earlier, despite Clarke's enthusiasm for the deterministic physics of his close friend Isaac Newton. Clarke defends against the charge that the final determination of the will, after consideration of the alternative possibilities, implies necessity and strict causal determinism
As to the former, viz., the necessity of the will's being determined by the last judgment of the understanding, this is only a necessity upon supposition, that is to say, a necessity that a man should will a thing, when it is supposed that he does will it; just as if one should affirm that everything which is, is therefore necessary to be, because when it is it cannot but be.Clarke makes a fine analogy to deflect foreknowledge as a cause. Our own knowledge that something is "certain" to happen has nothing to do with making it certain.
For first, the certainty of foreknowledge does not cause the certainty of things but is itself founded on the reality of their existence... We may illustrate this in some measure by the comparison of our own knowledge. We know certainly that some things are, and when we know that they are, they cannot but be; yet it is evident our knowledge does not at all affect the things to make them more necessary or more certain. Now foreknowledge in God is the very same as knowledge.But Clarke seems convinced that anything that now happens was already certain to happen in the past. He does not see the importance of Aristotle's future contingency or William James' "ambiguous futures." Clarke is an actualist.
Whatever now is, it is certain that it is, and it was yesterday and from eternity as certainly true that the thing would be today as it is now certain that it is. And this certainty of event is equally the same whether it be supposed that the thing could be foreknown or not. For whatever at any time is, it was certainly true from eternity, as to the event, that that thing would be; and this certain truth of every future event would not at all have been the less though there had been no such thing as foreknowledge. Bare prescience, therefore, has no influence at all upon anything, nor contributes in the least towards the making it necessary.