visual figure in the mind. The relation of sensory signs to the external things they signify originally is effected by a first principle of the mind without the use of reason. The first principles that yield our conceptions of qualities and objects yield convictions of the existence of these things at the same time. A question naturally arises as to the evidence of these convictions. First principles yield the convictions along with the conceptions, but do we have evidence of the existence of the qualities and objects we are convinced exist? We have the evidence of our senses, of our natural faculties, and that is all the evidence possible here. Reid’s point is that the convictions in questions resulting from the original principles of our faculties are immediately justified. Our faculties are, however, all fallible, so the justification that our original convictions possess may be refuted. We can now better understand Reid’s reply to Hume. To account for our convictions of the existence of body, we must abandon Hume’s theory of ideas, which cannot supply even the conception of body. We must discover both the original first principles that yield the conception and conviction of objects and their qualities, and first principles to account for our convictions of the past, of other thinking beings, and of morals. Just as there are first principles of perception that yield convictions of the existence of presently existing objects, so there are first principles of memory that yield the convictions of the existence of past things, principles of testimony that yield the convictions of the thoughts of others, and principles of morals that yield convictions of our obligations. Reid’s defense of a moral faculty alongside the faculties of perception and memory is striking. The moral faculty yields conceptions of the justice and injustice of an action in response to our conception of that action. Reid shrewdly notes that different people may conceive of the same action in different ways. I may conceive of giving some money as an action of gratitude, while you may consider it squandering money. How we conceive of an action depends on our moral education, but the response of our moral faculty to an action conceived in a specific way is original and the same in all who have the faculty. Hence differences in moral judgment are due, not to principles of the moral faculty, but to differences in how we conceive of our actions. This doctrine of a moral faculty again provides a counterpoint to the moral philosophy of Hume, for, according to Reid, judgments of justice and injustice pertaining to all matters, including promises, contracts, and property, arise from our natural faculties and do not depend on anything artificial.
Reid’s strategy for defending common sense is clear enough. He thinks that Hume showed that we cannot arrive at our convictions of external objects, of past events, of the thoughts of others, of morals, or, for that matter, of our own minds, from reasoning about impressions and ideas. Since those convictions are a fact, philosophy must account for them in the only way that remains, by the hypothesis of innate faculties that yield them. But do we have any evidence for these convictions? Evidence, Reid says, is the ground of belief, and our evidence is that of our faculties. Might our faculties deceive us? Reid answers that it is a first principle of our faculties that they are not fallacious. Why should we assume that our faculties are not fallacious? First, the belief is irresistible. However we wage war with first principles, the principles of common sense, they prevail in daily life. There we trust our faculties whether we choose to or not. Second, all philosophy depends on the assumption that our faculties are not fallacious. Here Reid employs an ad hominem argument against Hume, but one with philosophical force. Reid says that, in response to a total skeptic who decides to trust none of his faculties, he puts his hand over his mouth in silence. But Hume trusted reason and consciousness, and therefore is guilty of pragmatic inconsistency in calling the other faculties into doubt. They come from the same shop, Reid says, and he who calls one into doubt has no right to trust the others. All our faculties are fallible, and, therefore, we must, to avoid arbitrary favoritism, trust them all at the outset or trust none. The first principles of our faculties are trustworthy. They not only account for our convictions, but are the ground and evidence of those convictions. This nativism is the original engine of justification.
Reid’s theory of original perceptions is supplemented by a theory of acquired perceptions, those which incorporate the effects of habit and association, such as the perception of a passing coach. He distinguishes acquired perceptions from effects of reasoning. The most important way our original perceptions must be supplemented is by general conceptions. These result from a process whereby our attention is directed to some individual quality, e.g., the whiteness of a piece of paper, which he calls abstraction, and a further process of generalizing from the individual quality to the general conception of the universal whiteness shared by many individuals. Reid is a sophisticated nominalist; he says that the only things that exist are individual, but he includes individual qualities as well as individual objects. The reason is that individual qualities obviously exist and are needed as the basis of generalization. To generalize from an individual we must have some conception of what it is like, and this conception cannot be general, on pain of circularity or regress, but must be a conception of an individual quality, e.g., the whiteness of this paper, which it uniquely possesses. Universals, though predicated of objects to articulate our knowledge, do not exist. We can think of universals, just as we can think of centaurs, but though they are the objects of thought and predicated of individuals that exist, they do not themselves exist. Generalization is not driven by ontology but by utility. It is we and not nature that sort things into kinds in ways that are useful to us. This leads to a division-of-labor theory of meaning because general conceptions are the meanings of general words. Thus, in those domains in which there are experts, in science or the law, we defer to the experts concerning the general conceptions that are the most useful in the area in question. Reid’s theory of the intellectual powers, summarized briefly above, is supplemented by his theory of our active powers, those that lead to actions. His theory of the active powers includes a theory of the principles of actions. These include animal principles that operate without understanding, but the most salient and philosophically important part of Reid’s theory of the active powers is his theory of the rational principles of action, which involve understanding and the will. These rational principles are those in which we have a conception of the action to be performed and will its performance. Action thus involves an act of will or volition, but volitions as Reid conceived of them are not the esoteric inventions of philosophy but, instead, the commonplace activities of deciding and resolving to act. Reid is a libertarian and maintains that our liberty or freedom refutes the principle of necessity or determinism. Freedom requires the power to will the action and also the power not to will it. The principle of necessity tells us that our action was necessitated and, therefore, that it was not in our power not to have willed as we did. It is not sufficient for freedom, as Hume suggested, that we act as we will. We must also have the power to determine what we will. The reason is that willing is the means to the end of action, and he who lacks power over the means lacks power over the end.
This doctrine of the active power over the determinations of our will is founded on the central principle of Reid’s theory of the active powers, the principle of agent causation. The doctrine of acts of the will or volitions does not lead to a regress, as critics allege, because my act of will is an exercise of the most basic kind of causality, the efficient causality of an agent. I am the efficient cause of my acts of will. My act of will need not be caused by an antecedent act of will because my act of will is the result of my exercise of my causal power. This fact also refutes an objection to the doctrine of liberty – that if my action is not necessitated, then it is fortuitous. My free actions are caused, not fortuitous, though they are not necessitated, because they are caused by me.
How, one might inquire, do we know that we are free? The doubt that we are free is like other skeptical doubts, and receives a similar reply, namely, that the conviction of our freedom is a natural and original conviction arising from our faculties. It occurs prior to instruction and it is irresistible in practical life. Any person with two identical coins usable to pay for some item must be convinced that she can pay with the one or the other; and, unlike the ass of Buridan, she readily exercises her power to will the one or the other. The conviction of freedom is an original one, not the invention of philosophy, and it arises from the first principles of our natural faculties, which are trustworthy and not fallacious. The first principles of our faculties hang together like