The associationist who resolves these erroneous intuitions into the play of association, admits that the forces at work generating and consolidating the illusory belief are constant and permanent forces, and such as are not likely to be less effective in the future than they have been in the past.  Thus, he teaches that the intuition of the single object in the act of perception owes its strength to “inseparable association,” according to which law the ideas of the separate “possibilities of sensation,” which are all we know of the object, coalesce in the shape of an idea of a single uniting substance.  He adds, perhaps, that heredity has tended, and will still tend, to fix the habit of thus transforming an actual multiplicity into an imaginary unity.  And in thus arguing, he is allowing that the illusion is one which, to say the least of it, it will always be exceedingly difficult for reason to dislodge.

In view of this uncertainty, and of the possibility, if not the probability, of these beliefs remaining as they have remained, at least approximately universal, the man of science will probably be disposed to hold himself indifferently to the question.  He will be inclined to say, “What does it matter whether you call such an apparently permanent belief the correlative of a reality or an illusion?  Does it make any practical difference whether a universal ‘intuition,’ of which we cannot rid ourselves, be described as a uniformly recurring fiction of the imagination, or an integral constitutive factor of intelligence?  And, in considering the historical aspect of the question, does it not come to much the same thing whether such permanent mental products be spoken of as the attenuated forms or ghostly survivals of more substantial primitive illusions (for example, anthropomorphic representations of material objects, ‘animistic’ representations of mind and personality), or as the slowly perfected results of intellectual evolution?”

This attitude of the scientific mind towards philosophic problems will be confirmed when it is seen that those who seek to resolve stable common convictions into illusions are forced, by their very mode of demonstration, to allow these intuitions a measure of validity.  Thus, the ideas of the unity and externality attributed to the object in the act of perception are said by the associationist to answer to a matter of fact, namely, the permanent coexistence of certain possibilities of sensation, and the dependence of the single sensations of the individual on the presence of the most permanent of these possibilities, namely, those of the active or muscular and passive sensations of touch, which are, moreover, by far the most constant for all minds.  Similarly, the idea of a necessary connection between cause and effect, even if illusory in so far as it expresses an objective necessity, is allowed to be true as an expression of that uniformity of our experience which all scientific progress tends to