‘To speak, to reason, to form general or abstract ideas, are then in fact the same thing: and this truth, simple as it is, might pass for a discovery. Certainly, men in general have not had any notion of it; this is evident from the manner in which they speak and reason; it is evident from the abuse which they make of abstract ideas; finally, it is evident from the difficulties which those persons confessedly find in conceiving of abstract ideas who have so little in speaking of them.
‘The art of reasoning resolves into the construction of languages, only because the order of our ideas itself depends entirely on the subordination that subsists between the names given to genera and species; and as we arrive at new ideas only by forming new classes, it follows that we can only determine or define our ideas by determining their classes. In this case we should reason well, because we should be guided by analogy in our conclusions as well as in the acceptation of words.
‘Convinced, therefore, that classes or sorts of things are pure denominations, we shall never think of supposing that there exist in nature genera or species; and we shall understand by these words nothing but a certain mode of classing things according to the relations which they have to ourselves and to one another. We shall be sensible that we can only discover those relations, and not what the things truly are.’
Berkeley handled his subjects with little tenderness, and he has perfectly anatomised this subject of abstract ideas. In choosing to answer the objections to this doctrine as stated by him, I shall not be accused of wishing to encounter a mean adversary. I can only trust to the goodness of my cause. I hope I shall be excused for going at some length into the argument, because it is one of the most difficult and complicated in itself, and is of the most extensive application to other questions relating to the human understanding. If we can come to any satisfactory issue to it, it will be worth the pains of enquiry.
‘It is agreed on all hands,’ says this author, ‘that the quantities or modes of things do never really exist in each of them, apart by itself, and separated from all others, but are mixed, as it were, and blended together, several in the same object. But we are told the mind being able to consider each quality singly, or abstracted from those other qualities with which it is united, does by that means frame to itself abstract ideas. For example, there is perceived by sight, an object, extended, coloured, and moved. This mixed idea the mind resolving into its simple constituent parts, and viewing each by itself exclusive of the rest, does frame the abstract ideas of extension, colour, and motion. Not that it is possible for colour or motion to exist without extension, but only that the mind can frame to itself by abstraction the idea of colour, exclusive of extension, and of motion exclusive both of colour and extension. Again, the mind having observed that in the particular extensions perceived by sense, there is something common and alike in all, and some other things peculiar, as this or that figure, or magnitude, which distinguish them one from another, it considers apart, or singles out by itself that which is most common, making thereof a most abstract idea of extension, line, surface, or solid, nor has any figure or magnitude, but is an idea prescinded from all these. So likewise the mind by leaving out of the particular colours perceived by sense, that which distinguishes them one from another, and retaining that which only is common to all, makes an idea of colour in abstract, which is neither red, nor blue, not white, &c. And in like manner by considering motion abstractedly, not only the body moved, but likewise from the figure it describes, and all particular directions and velocities, the abstract idea of motion is framed, which equally corresponds to all particular motions whatsoever that may be perceived by sense.
‘And as the mind frames to itself abstract ideas of qualities, or modes, so does it by the precision or mental separation, attain abstract ideas of the more compound beings, which include several co-existent qualities:—for example, the mind having observed, that Peter, James, John, &c., resemble each other in certain common agreements of shape, and other qualities, leaves out of the complex or compounded idea it has of Peter, James, &c., that which is peculiar to each, retaining only what is common to all; and so makes an abstract idea wherein the particulars equally partake, abstracting entirely, and cutting off all those circumstances and differences which might determine it, to any particular existence. And after this manner it is said, we come by the abstract idea of man, or if you please humanity, or human nature; ’tis true, there is included colour, because there is no man but has some colour, but then it can be neither white nor black, nor any particular colour, because there is no one particular colour, wherein all men partake; so there is included stature, but then it is neither tall stature, nor low stature, nor yet middle stature, but something abstracted from all these; and so of the rest. Moreover, there being a great variety of other creatures that partake in some parts, not all, of the complex idea, man, the mind leaving out those parts which are peculiar to men, and retaining those only which are common to all living creatures, frames the idea of animals, which abstracts not only from all particular men, but also, all birds, beasts, fishes, and insects. By Body is meant body without any particular shape, or figure, there being no one shape or figure common to all animals, without covering of hair, feathers, or scales, &c. nor yet naked; hair, feathers, scales, and nakedness, being the distinguishing properties of particular animals, and for that reason left out of the abstract idea; upon the same account the spontaneous motion must be neither in walking, nor flying, nor creeping, it is nevertheless a motion, but what that motion is, it is not easy to conceive.’
‘Whether others have this wonderful faculty of abstracting their ideas, they best can tell: for myself I dare be confident I have it not. I have a faculty of imagining or representing to myself the ideas of those particular things I have perceived, and of variously compounding and dividing them. I can imagine a man with two heads or the upper part of a man joined to the body of a horse; I can consider the hand, the eye, the nose, each by itself, abstracted or separated from the rest of the body. But then, whatever hand or eye, I imagine, it must have some particular shape, and colour. Likewise, the idea of man that I frame to myself must be either of a white, or a black, or a tawny; a strait, or a crooked; a tall, or a low, or a middle-sized man. I cannot by any effort of thought conceive the abstract idea above-described: and it is equally impossible for me to form the abstract idea of motion distinct from the body moving, and which is neither swift nor slow, curvilinear nor rectilinear, and the like may be said of other abstract general ideas whatsoever: to be plain, I own myself able to abstract in one sense, as when I consider some particular parts or qualities separated from others, with which, though they are united in some objects, yet it is possible they may really exist without them. But I deny that I can abstract from one another, or conceive separately those qualities, which it is impossible should exist so separated:—or that I can frame a general notion by abstracting from particulars in the manner aforesaid, which two last are the proper acceptation of abstraction; and there is ground to think most men will acknowledge themselves to be in my case.
‘The generality of men, which are simple and illiterate, never pretend to abstract notions. It is said they are difficult and not to be attained without pains and study; we may therefore reasonably conclude that, if such there be, they are confined only to the learned. I proceed to examine what can be alleged in defence of the doctrine of abstraction, and try if I can discover what it is that inclines the man of speculation to embrace an opinion so remote from common sense as that seems to be. There has been a late excellent and deservedly esteemed philosopher, who no doubt has given it very much, by seeming to think the having abstract general ideas is what puts the difference in point of understanding betwixt man and beast.’
The author here quotes a passage from Mr. Locke on the subject, which it is not necessary to give, and afterwards his opinion that words become general by being made signs of general ideas. He then proceeds:—‘To this I cannot assent, being of opinion that a word becomes general by being made the sign, not of an abstract general idea, but of several particular ideas, any one of which it indifferently suggests to the mind.’
‘If we will annex a meaning to our words and speak only of what we can only conceive, I believe we shall acknowledge that an idea, which considered in itself is particular, becomes general, by being made to represent or stand for all other particular ideas of the same sort. To make this plain by example, suppose a geometrician is demonstrating the method of cutting a line in two equal parts. He draws for instance a black line of an inch in length: this which is in itself a particular line, is nevertheless, with regard to its signification, general, since, as it is there used, it represents all particular lines whatsoever, so that what is demonstrated of it is demonstrated of all lines, or in other words of a line in general; and, as that particular line becomes general, by being made a sign, so the name line, which taken absolutely, is particular, by being a sign, is made general. And as the former owes its generality not to its being the sign of an abstract or general line, but of all particular right lines that may possibly exist, so the latter must be thought to derive its generality from the same cause, namely, the various particular lines which it indifferently denotes.’