edly he had a strong belief that such a demonstration was practicable; and this belief prompted him to acquiesce with greater confidence in the result of the Induction. For this very reason, this instance appears to be a typical and instructive case of Inductive reasoning. Pure Induction is exclusively an organon of discovery, a clew for anticipating facts not yet observed and truths not yet proved. The Ground of the Induction, that is, the proof, if it may be called such, or the source of the confidence with which we accept its conclusions, is an indistinct assurance, derived from a priori considerations, that the results might be demonstrated, if we were acquainted with all the circumstances. of the case. Newton's assurance was founded on his indistinct anticipation of the truth, that the formation of the coefficients of the series must depend in some manner on the laws of the permutation and combination of numbers, an anticipation which he did not stop to work out and verify. The physicist's assurance is based primarily, as we have seen, on his necessary conviction that every event or change must have an efficient Cause, a truth which is readily explicated into the maxim that Nature's course is uniform; and secondarily, upon his belief that the proportional variation of the successive terms in such a series as is called a Law of Nature is another consequence of the axiomatic principle of Causality, that effects must be proportional to their Causes. The physicist's anticipation cannot be verified, because, in the physical universe, Efficient Causes lie beyond the reach of human insight. We can discover nothing but Invariable Antecedents. But so strong is the bias which leads us to identify an Invariable Antecedent with an Efficient Cause, that the phraseology of Causation is still employed throughout our investigations, though it has been demonstrated over and over again, that constancy of sequence is no certain indication of causal efficiency. We still speak of physical Causes, of agents

and their action, of forces and powers, although it is now admitted on all hands that we mean nothing by such language, when employed with reference to the material universe, except "constant relations of succession or of similarity." The very persistency of this inappropriate phraseology indicates quite clearly the source of our conviction that Nature's course is uniform, and her Laws unchangeable, except by Him whose infinite wisdom first established them, and whose unvarying purposes and modes of action they express.

CHAPTER XIII.

THE SOURCES OF EVIDENCE AND THE CAUSES OF ERROR.

NTUITION is not only the source in which all our

INTU

knowledge originates, but it is the universal basis of certainty, or the sole ground of the confidence with which we accept any facts or truths as known. What we directly or immediately perceive, whether by the external senses or by consciousness, that we know. What is not thus directly perceived is entitled to be called knowledge only in a secondary or derivative sense; properly speaking, it is only an inference from our knowledge, and however legitimate this Inference may be, it is worth nothing if the truth of one or more Intuitions, on which it depends, be not previously taken for granted. Take even Demonstrative Reasoning, for instance, in which it is rightly said that the Conclusion is a necessary inference from the Premises. Still, before we can accept this Conclusion as certain, we must assume that both the Premises are true. Now, whatever be the nature of the Major Preinise, the Subsumption must express, either directly or indirectly, a truth of Intuition. We can knowingly assert that a given object possesses a certain attribute, or bears a certain relation of likeness or unlikeness to some other object, only through our direct perception of this fact either by sense or consciousness; and such an assertion must enter into every act of Reasoning, as one of the grounds on which the Conclusion rests. Any Reasoning, then, by which we might attempt to doubt or deny the validity of our Intuitions, would be

self-destructive; for in such Reasoning, the truthfulness of our Intuitive faculties must be presupposed, or taken for granted. We should, by such scepticism, deny the legitimacy of our own denial.

Intuition, therefore, is the highest source of evidence, and the ultimate foundation of all certainty. If we cannot accept, as absolutely true, what we immediately perceive, or are conscious of, then we can know nothing; we cannot even know that we do not know. But before we place this absolute reliance upon Intuition or Perception, we must carefully distinguish what it is that we really perceive, or, in other words, what that is of which we have an Intuition. In ordinary mental action, Inferences are so quickly and habitually drawn from Intuitions, and thereby so closely blended with them, acts of comparison and generalization also entering into the compound result, that it becomes extremely difficult to separate the pure Matter of Intuition, of which we are absolutely certain, from the heterogeneous ingredients which are thus united with it, and of which we are not by any means equally sure. Hence it is often said that our senses deceive us, when the truth is, that we are mistaken only in the Inferences which we have incorrectly drawn from the data actually furnished by the senses. Thus we are often deceived into accepting a counterfeit as a good coin; but the mental act which thus leads us into a mistaken belief is really compound, embracing an act of memory, one of generalization, and one of Reasoning. The little object placed in our hands for examination is perceived to have a certain color, weight, shape, stamp, &c.; and it is impossible that these qualities should be, to us, in any respect different from what they are perceived to be. But when we proceed to compare these qualities with others which we remember to have perceived at some other time in good coins, and to infer from their similarity that this supposed coin is not a

་་་་

counterfeit, it is evident that we are exposed to many sources of error. Even if we go so far only as to designate one of these qualities by its Common Name, -- to say, for instance, that this coin is yellow, we go beyond the Intuition, and, so far, become liable to mistake; it may well be that we have but an imperfect recollection and imagination of the color which is usually so called, and therefore may be mistaken in supposing that this color is so similar to it as to merit the same name. In like manner, any other comparison, as of the weight, shape, or stamp, as it requires either memory, if both objects be not actually before us, or a decision as to the degree of similarity, if they are both present to sense, must involve an element of uncertainty.

The question has been raised, whether external objects are directly perceived by us as external, or whether their externality is an Inference subsequently drawn from this perception as combined with others, and as governed by the necessary and a priori convictions of the mind. In other words, is the externality of the object, or the fact that it is something different from myself, that it is not-me, a constituent part of the Intuition, or only an Inference from it? If the former supposition be true, then I know that the external world exists, and any Reasoning upon the case, either for or against this knowledge, is superfluous, and even illogical; for as Reasoning must involve and depend upon Intuition, it cannot contradict Intuition. But if the latter supposition be correct, then the reality of the outward universe is not, strictly speaking, known, but only inferred through an act of the understanding, which, as it purports to relate to real objects, and not to a mere conception of the mind, certainly may be a mistaken one.

The question is an important one, but the full discussion of it belongs to Metaphysics, and not to Logic. We can only consider here the nature and the relevancy of the evi