The question as to the validity of moral intuitions being thus separated from the simple question ‘whether they actually exist,’ it becomes obvious that the latter can only be decided for each person by direct introspection or reflection. It must not therefore be supposed that its decision is a simple matter, introspection being always infallible: on the contrary, experience leads me to regard men as often liable to confound with moral intuitions other states or acts of mind essentially different from them,--blind impulses to certain kinds of action or vague sentiments of preference for them, or conclusions from rapid and half-unconscious processes of reasoning, or current opinions to which familiarity has given an illusory air of self-evidence. But any errors of this kind, due to careless or superficial reflection, can only be cured by more careful reflection. This may indeed be much aided by communication with other minds; it may also be aided, in a subordinate way, by an inquiry into the antecedents of the apparent intuition, which may suggest to the reflective mind sources of error to which a superficial view of it is liable. Still the question whether a certain judgment presents itself to the reflective mind as intuitively known cannot be decided by any inquiry into its antecedents or causes.[170]
It is, however, still possible to hold that an inquiry into the Origin of moral intuitions must be decisive in determining their Validity. And in fact it has been often assumed, both by Intuitionists and their opponents, that if our moral faculty can be shown to be ‘derived’ or ‘developed’ out of other pre-existent elements of mind or consciousness, a reason is thereby given for distrusting it; while if, on the other hand, it can be shown to have existed in the human mind from its origin, its trustworthiness is thereby established. Either assumption appears to me devoid of foundation. On the one hand, I can see no ground for supposing that a faculty thus derived, is, as such, more liable to error than if its existence in the individual possessing it had been differently caused:[171] to put it otherwise, I cannot see how the mere ascertainment that certain apparently self-evident judgments have been caused in known and determinate ways, can be in itself a valid ground for distrusting this class of apparent cognitions. I cannot even admit that those who affirm the truth of such judgments are bound to show in their causes a tendency to make them true: indeed the acceptance of any such _onus probandi_ would seem to me to render the attainment of philosophical certitude impossible. For the premises of the required demonstration must consist of caused beliefs, which as having been caused will equally stand in need of being proved true, and so on _ad infinitum_: unless it be held that we can find among the premises of our reasonings certain apparently self-evident judgments which have had no antecedent causes, and that these are therefore to be accepted as valid without proof. But such an assertion would be an extravagant paradox: and, if it be admitted that all beliefs are equally in the position of being effects of antecedent causes, it seems evident that this characteristic alone cannot serve to invalidate any of them.