LETTER XII.

THE AMBIGUITY OF CERTAIN TERMS.

My present Epistle you will please to regard as forming a sort of parenthesis.

The view which I have taken in the preceding Letters of the operations and affections of the mind, if it have no other value, will enable me, as I before remarked, to speak of them with a considerable degree of precision.

With the same design of attaining and assisting others to attain precision of language, I purpose in my present Letter to call your attention to an important ambiguity, if I may so denominate it, to which some of the expressions employed both by myself and others in the designation and description of mental phenomena are liable.

What I allude to is well exemplified in the double use (almost unavoidable) of the term perception, and the occasional confusion and false inferences thence arising.

This is a species of relative term which designates what for want of a better name may be described as a double, or compound, or two-sided, but yet indivisible fact. Just as a leaf or piece of paper must

have two sides that may be separately viewed but cannot be disjoined, so there are some facts which consist of two parts equally inseparable in reality although distinguishable in description. Should this statement strike you as not very clear, a brief explanation may, I hope, elucidate it.

It is plain that there can be no perception without both a percipient being and an object perceived; and, conversely, there can be no object perceived without a percipient being. Both the act of the percipient being, and the object which he perceives, are expressed or implied in the word perception, forming essential and inseparable parts of its meaning; and this leads to the use of the term in two modes, according to the part or side of the phenomenon which happens to be principally contemplated at the time or is most prominently in view. When our attention is directed to the percipient being, we employ the term perception to denote his act, coupling it probably with the mention of the object, as, for instance, in the sentence, "his perception of the scene was momentary," in which connexion the word is equivalent to the active participle perceiving.

When our attention, on the other hand, is chiefly directed to the object perceived, we frequently designate the latter by the same term, particularly when the word is used with the indefinite article or in the plural number. We are constantly speaking of our “perceptions" when we intend simply

the objects perceived, as in the expression, "our recollections, or conceptions, are copies of our perceptions," meaning copies of what we have perceived, not of our acts of perceiving, although the latter are necessarily implied-copies, in fact, of external objects.

Now, although the term should in rigour be restricted to the act or state of the mind, yet it may, without inconsistency and confusion, be employed in this latter way to designate external objects in contraposition to recollections, or conceptions, or, as I should prefer calling them, representative ideas, or simply ideas.

But there are two other modes of using it, which are not equally harmless; one of them being selfinconsistent, and the other being confused.

The self-inconsistent mode is when in the same argument the word is employed first to denote the mental act and then the objects of the act, as in the reasoning that because perception is an operation purely mental, therefore, all our perceptionsmeaning the objects perceived-are mental; or, putting the conclusion in still stronger language, [' therefore the objects perceived have no existence but in the mind.

The confused mode is when the term is employed so as really to imply (often undesignedly) something distinct on the one hand from the act of the percipient being, and on the other from the object perceived, as when it is said that our perceptions are like or unlike external objects.

Here the term cannot be applied to our acts of perceiving, for no one would think of affirming our acts of perceiving to be like or unlike the objects perceived; nor can it be applied to the objects perceived, for that would be pronouncing the said objects to be like or unlike themselves. What, then, is the phrase "perception" here intended to designate? It is not the act, it cannot be the object. Where, then, are we to look for the tertium quid which is to give to the proposition the reality or even the semblance of a meaning? Or how is it that such a comparison has ever been made, and such a resemblance or non-resemblance predicated?

In a subsequent Letter I shall find a fitting place for an attempt to solve the problem, leaving it in the mean time as an exercise for your metaphysical sagacity.

The acceptation of the word before us becomes still more unsteady with those philosophers who speak of faculties and powers. It is apt in their writings to have a triple meaning, in some places denoting the faculty of perception, in others the act of perceiving, and in others the objects perceived. And in addition to these acceptations I may mention the very objectionable practice of some writers (Hume for instance) who speak of perceptions when they mean conceptions or ideas*, naturally, to be sure, on their theories.

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Nothing can ever be present to the mind but an image or perception."-Academical or Sceptical Philosophy.

This remark leads me to notice that with the word conception there is not the same liability to error from ambiguity as with the word perception; or, to express myself more precisely, while the latter may be used, as just mentioned, in three senses, the former can be used only in two.

In a passage which I quoted in a former Letter, Dugald Stewart furnishes an instance in point. "The business of conception," he remarks," is to present us with an exact transcript of what we have felt or perceived," meaning of course that it is the business of the faculty so called.

He adds: "But we have, moreover, a power of modifying our conceptions, by combining the parts of different ones together, so as to form new wholes of our own creation;" in which passage he manifestly intends to designate, not the faculty itself, but the transcripts which, according to him, it is the business of the faculty to present.

Thus we may speak of the faculty of conception, and of the products or acts of that faculty -conceptions; but there is not, as in the case of perception, a separate object which can be confounded with the act under one name. We do, indeed, speak of the objects conceived or recollected; but it is manifest that these objects, not being actually in presence, bear to the act of conceiving them a very different relation from that which objects actually perceived bear to the act of perception.