But the contribution made by psychology to the solution of the problem has taken the form not so much of a direct reinforcement of the arguments of either of the opponent systems, as of a searching criticism of the false assumptions concerning conative processes and the phenomena of choice common alike to determinists and libertarians.
But, nevertheless, the new light thrown upon the unity of the self and the more careful and accurate scrutiny made by recent psychologists of the phenomena of decision have rendered it no longer possible either for determinists to deny the fact of choice (whatever be their theory as to its nature) or for libertarians to regard the self or the will as isolated from and unaffected by other mental constituents and antecedents, and hence, by an appeal to wholly fictitious entities, to prove the truth of freedom.
What is opposed to obligation, or at least always distinguished from it, is that very domain of necessity within which determinists would bring the will.
We must now consider the arguments by which determinists attack the position of their opponents and the evidence which they adduce to show that the freedom of the will is no necessary postulate for moral action.
Modern determinists differ from the earlier advocates of their theory in their endeavour to exhibit at least the compatibility of morality with the absence of freedom, if not the enhancement of moral values which, according to some of its advocates, follows upon the acceptance of the deterministic account of conduct.