COMMON SENSE, True PHILOSOPHY OF. There are certain beliefs that have been current among men in all ages, which, when canvassed by one set of philosophers, have been declared tobe groundless illusions. Of these, the most remarkable instance is the belief in an external, material world, independent of any mind to perceive it. The doc trine put forth by bishop Berkeley, as opposed to the common opinion, was, that " the whole universe subsists, and can only subsist, within such a sentient, invisible, and con scious thing as the mind is known to be. In this way, each human mind must have within it a separate universe of its own, but so exactly the same in all minds, that every object of sense, and every movement of every object that is to be found in the universe of one mind, is to be found also in the universe that is within the other mind; the general effect of all which conditions is much the same as that which would be pro duced if several people were all dreaming, exactly at the same time, exactly the same dream." "The result of Berkeley's inquiry," says Dr. Reid, "was a serious conviction that there is no such thing as a material world—nothing in nature but spirits and ideas; and that the belief of material substances, and of abstract ideas, are the chief causes of all our errors in philosophy, and of all infidelity and heresy in religion. His arguments are founded upon the principles which were formerly laid down by Des Cartes, Male branehe, and Locke, and which have been very generally received. And the opinion of the ablest judges seems to be, that they neither have been nor can be confuted; and that lie bath proved, by unanswerable arguments, what no man in his senses can believe. Hume proceeds upon the same principles, but carries them to their full length; and as the bishop undid the whole material world, this author, upon the same grounds, undoes the world of spirits, and leaves nothing in nature but ideas and impressions, without any subject on which they may be impressed. "—Inquiry into the Human Mind, c. 1, s. 5.
A dead-lock in philosophy was the result of those doctrines of Berkeley and Hume; and the solution offered by Reid consisted in setting up C. S. as an arbiter from which there could be no appeal; that is to say, the universally admitted impressions of mankind were to be taken as corresponding to the fact of things without any further scrutiny. Reid's philosophy of C. S. has thus found a place in the thinking world ; and it is only the same view otherwise expressed, when it is declared by other philosophers that the deliverance of consciousness must be presumed true. Sir W. Hamilton, in the most elaborate vindication of the C. S. philosophy that has ever been produced (edition of Reid's works), dwells largely upon this last view of the subject. The following extract is a specimen of his mode of reasoning: " When, for example, consciousness assures us that, in perception, we are immediately cognizant of an external and extended (not-self); or that, in remembrance, through the imagination, of which we are immediately cognizant, we obtain a mediate knowledge of a real past: how shall we repel the doubt—in the former case, that what is given as the extended reality itself is not merely a representation of matter by mind; in the latter, that what is given as a mediate knowledge of the Mst, is not a mere present phantasm, containing an illusive reference to a real past? We can do this only in one way. The legitimacy of such gratuitous doubt necessarily supposes that the deliverance of consciousness is not to be presumed true. If, therefore, it can be shown, on the one hand, that the deliv
erances of consciousness must philosophically be accepted until their certain or probable falsehood has been positively evinced; and if, on the other hand, it cannot be shown that any attempt to discredit the veracity of consciousness has ever yet succeeded; it follows that, as philosophy now stands, the testimony of consciousness must be viewed as high above suspicion, and its declarations entitled'to demand prompt and uncon ditional assent." " In the first place, it cannot but be acknowledged that the veracity of consciousness must at least, in the first instance, be conceded. Nature is not gratuitously to be assumed to work, not only in vain, but in counteraction of herself." "But in the second place, though the veracity of the primary convictions of consciousness must, in the out set, be admitted, it still remains competent to lead a proof that they are undeserving of credit. But how is this to be done? As the ultimate grounds of knowledge, these convictions cannot be redargued from any higher knowledge; and as original beliefs, they are paramount in certainty to every derivative assurance." "It will argue nothing against the trnstworthiness of consciousness, that all or any of its deliverances are inex plicable—are incomprehensible. To make the comprehensibility of a datum of con sciousness the criterion of its truth, would be indeed the climax of absurdity." (P. 745.) The conclusiveness of this reasoning is disputed by many, who object, that con sciousness (q.v.) is a very wide word, comprising indeed everything that we call mind; and it is proverbially unsafe to argue in generalities. Suppose, it is argued, We were to substitute "memory" in the above reasonings, and to maintain that the veracity of each one's memory was beyond all question or dispute. it would be apparent at once Low the case really stands. In one meaning, and in one set of circumstances, memory is sure, or even, if we please, infallible—that is, when we record an observation the moment after we have made it. For a short interval of time, a simple fact, or a brief statement, may be recollected with entire certainty. On the other hand, the lapse of days, months, or years, and the complicity of the fact, not to mention the bias of the feelings, are known to cause great uncertainty in our recollection, and in such circumstances we do not implicitly rely on it. In a word, experience is the criterion of how far the memory is to be trusted. Possibly, therefore, tic; same thing may turn out to be true of the larger fact named consciousness.
The truths of C. S., or consciousness, are such as these: the laws of identity, contra diction, and excluded middle (see IDENTITY); the axioms of mathematics; the law of causality (see CAUSE); the doctrine of an innate moral sense (see E'rrncs); the doctrine of man's moral liberty (see FREE WILL); the existence of an external world independ ent of every percipient mind. Such truths are designated by a variety of other names, i with a view to contrast them with what we learn in the course of our education and contact with the world; they arc termed intuitions, intuitive cognitions, instincts, feel ings, beliefs, principles, ultimate or primordial elements, truths a priori, transcendental cognitions, truths of the reason, cte.—Hamilton's Dissertations, note A. The philosophy of C. S.. as promulgated by Reid, bore reference especially to the denial by Berkeley Of the received view of the material world—a subject which falls to be considered under PERCEPTION.