T 2.3.1.12

To this I reply, that in judging of the actions of men we must proceed upon the same maxims, as when we reason concerning external objects. When any phænomena are constantly and invariably conjoin'd together, they acquire such a connexion in the imagination, that it passes from one to the other, without any doubt or hesitation. But below this there are many inferior degrees of evidence and probability, nor does one single contrariety of experiment entirely destroy all our reasoning. The mind ballances the contrary experiments, and deducting the inferior from the superior, proceeds with that degree of assurance or evidence, which remains. Even when these contrary experiments are entirely equal, we remove not the notion of causes and necessity; but supposing that the usual contrariety proceeds |from the operation of contrary and conceal'd causes, we conclude, that the chance or indifference lies only in our judgment on account of our imperfect knowledge, not in the things themselves, which are in every case equally necessary, tho' to appearance not equally constant or certain. No union can be more constant and certain, than that of some actions with some motives and characters; and if in other cases the union is uncertain, 'tis no more than what happens in the operations of body, nor can we conclude any thing from the one irregularity, which will not follow equally from the other.