I think it is fairly plain that the ability or otherwise of this explanation to meet the facts turns upon the phrase 'sufficient mental maturity.' If the kind of mental maturity which may legitimately be regarded as a condition of the apprehension of self-evident truths is such as may plausibly be supposed to be lacking in those who fail to appreciate the alleged self-evident obligations - whatever they may happen to be - of the In-tuitionalist, then there is force in the Intuitionalisms argument. But if, as I suspect, that hypothesis cannot be sustained, the Intuitionalist's argument breaks down. Let us consider, then, what kind of 'mental maturity' may justly be demanded as a condition of the apprehension of self-evident truths.
1 The Right and the Good, p. 29. Italics mine.
We may eliminate one kind of mental maturity at once. It is not necessary to have the mental maturity which consists in the ability to maintain before the mind a complex system of conceptual relationships. That ability, in greater or less degree, is indispensable for the apprehension of inferential truths - e.g. for the apprehension of the truth of the conclusion in a geometrical demonstration. But it is of the essence of 'self-evident' truths, admittedly, that the proposition in question can be seen to be true 'within the four corners of its own being.' Its 'evidence' lies wholly within itself. The mind, therefore, does not need to be capable of sustaining anything in the nature of a train of reasoning in order to be capable of apprehending a self-evident truth. Hence, although primitive peoples are, no doubt, 'mentally immature' in this regard, this kind of immaturity should not preclude them from the capacity to apprehend self-evident moral truths.
And we can eliminate another kind of mental maturity likewise. The mental maturity which consists in the possession of an ample store of knowledge of facts - the 'well-stocked mind' - can have nothing to do with the present case. To most people, it is true, this kind of maturity seems extremely important for moral knowledge. But that is just because to most people the Tightness of acts is at least largely determined by the consequences they produce - information as to probable consequences being thus indispensable to the ascertainment of particular rightnesses. But for the apprehension of the Intuitionalist's 'self-evident' obligations information as to the consequences of the acts to which they relate is plainly irrelevant The evidence of the 'self-evident' obligation lies (to repeat) wholly within itself.
What, then, is the kind of mental maturity that can be legitimately supposed to be a condition of competence to apprehend self-evident truths? So far as I can see, it is of this nature. The mind must have such maturity as enables it to understand the meaning of the different terms in the proposition, and it must have such maturity as enables it to make the effort of abstract thought required to 'hold together' the different 'terms' in their propositional relationship. Granted these conditions, it seems to me that a truth that is really self-evident must be evident to any mind that attends to it.
Is this not, after all, what we all assume with regard to the self-evidence of mathematical axioms? Take the proposition 'if equals be taken from equals, the remainders are equals.' Given a mind which understands the meaning of the different terms, and which is capable of holding the terms together in their propositional relationship (and thus of understanding the meaning of the whole proposition), and that mind, we all assume, cannot, if it attends to the proposition, withhold its assent from it. For what is there which could obstruct its apprehension, granted these conditions, and granted that the proposition is really self-evident? Nothing, it would seem, but the possession of a different kind of mind, a mind that works according to quite different principles. And no one is likely to wish to take refuge in the sceptical hypothesis that there are 'minds' intrinsically different in the principle of their operation.
But if it be admitted that it is only the kind of mental maturity which we have just described which is rightly esteemed a pre-condition of competence to apprehend self-evident truths, is it really plausible to explain the apparent incapacity of so many persons to apprehend the alleged self-evident truths of the ethical Intuitionalist as being due to their 'mental immaturity?' It is very difficult, indeed, to believe this. Undoubtedly, primitive peoples are seriously defective both as regards insight into 'consequences' and as regards capacity to perform any intricate piece of abstract reasoning. But these defects, we have seen, arc irrelevant to the present issue. What matters is that they should be able to understand the meaning of terms like promising, lying, gratitude, benefactor, etc., and also, of course, what is meant by the term 'ought' itself: and again, that they should be sufficiently developed in their thinking powers to be able to take in the meaning of a total proposition like 'gratitude ought to be shown to benefactors.' Surely it is paradoxical to maintain that these very elementary conditions are not in very large measure satisfied among all save the most barbaric races? Yet many of the communities which sharply dissent from the Intuitionalist's set of obligations are far removed from the status of the 'barbarian'.
It is just conceivable, however, that the Intuitionalist might be prepared to admit that most of those who acquiesce in other codes do have the capacity to apprehend the alleged self-evident obligations. He might try to explain their failure to apprehend them on the ground that they have not had occasion to give proper attention to the general propositions in which they are expressed. And it is true enough, of course, that not many of the persons in question have set themselves, or been set, to 'consider' these propositions. On the other hand, if they have not had the opportunity to appreciate the 'general proposition,' they have had ample occasion to appreciate its particularised expression in reference to individual acts in their experience. And this particularised expression is supposed by the Intuitionalist to be equally a self-evident proposition. Indeed, if we are to believe Mr Ross,1 it is from the apprehension of the self-evident rightness (for Mr Ross, prima facie rightness) of an individual act of a particular type that we ultimately come to apprehend the self-evident 'general principle' relating to that type. Yet the actual facts of the case are that these persons who have failed to apprehend the alleged self-evident principles have been every bit as unsatisfactory in failing to apprehend the alleged self-evident particularised expression. The failure does not seem to be accounted for, therefore, by mere lack of opportunity.