EXISTENCE, that whereby any thing has an actual essence, or is said to he. Mr. Locke says, "that we arrive at the knowledge of our own existence by intu ition ; of the existence of Cod by demon stration; and of other things by sensation. As for our own existence," continues that great philosopher, " we perceive it so plainly, that it neither needs, nor is capa ble of any proof. I think, I reason, I feel pleasure and pain ; can any of these be more evident to me than my own exist ence ? If I doubt of all other things, that very doubt makes me perceive my own existence, and will not suffer me to doubt it. If I know 1 doubt, I have as certain a perception of the thing doubting, as of that thought which 1 call doubt : experi ence then convinces us that we have an intuitive knowledge of our own exist tence." From the knowledge of our own ex istence, Mr. Locke deduces his demon stration of the existence of a God.
It has been a subject of great dispute, whether external bodies have any exist ence but in the mind, that is, whether they really exist, or exist in idea only : the opinion is supported by Mr. Locke, and the latter by 1)r. Berkely. "The knowledge of the existence of other things, or things without the mind, we have only by sensation : for there being no necessary connection of real existence with any idea a man hath in his memory, nor of any other existence but that of God, with the existence of any particular man ; no particular man can know the existence of any other being, but only when, by operating upon him, it makes itself be perceived by him. The having the idea of any thing in our mind no more proves the existence of that thing, than the picture of a man evidences his being in the world, or the visions of a dream make a true history. It is, therefore, the actual receiving of ideas from without that gives us notice of the existence of other things, and makes us know that something does exist at that time without us, which causes that idea in us, though perhaps we neither know nor consider how it does it. This notice, which we have by our senses, of the existence of things without us, though it be not altogether so certain as intuition and demonstration, yet deserves the name of knowledge, if we persuade ourselves that our faculties act and inform us right concerning the existence of those objects that affect them : but besides the assur ance we have from our senses themselves, that they do not err in the information they give us of the existence of things without us, we have other concurrent reasons ; as, first, it is plain these per ceptions are produced in us by external causes affecting our senses, because those that want _the organs of any se:,se never can have the ideas belonging to that sense in their minds. Se condly, because' we find sometimes that we cannot avoid the having those ideas produced in our minds. When my eyes are shut, I can, at pleasure, recal to my mind the ideas of light, or the sun, which, former sensations had lodged in my me mory ; but if I turn my eyes towards the sun, I cannot avoid the ideas which the light of the sun then produces in me ; which shews a manifest difference be tween those ideas laid up in the memory, and such as force themselves upon us, and we cannot avoid having ; besides, there is nobody who Both not perceive the dif ference in himself between actually look ing on the sun, and contemplating the idea he has of it in his memory ; and therefore he hath certain knowledge that they are not both memory or fancy. Thirdly, add to this, that many ideas are produced in us with pain, which we after wards remember without the least of : thus, the pain of heat or cold, when the idea of it is revived in our minds, give us no disturbance, which, when felt, was very troublesome ; and we remember the pain of hunger, thirst, head-ach, &c. without any pain at all, which would either never disturb us, or else constantly do it, as often as we thought of it, were there no more but ideas float ing in our minds, and appearances enter taining our fancies, without the real ex istence of things affecting us from abroad. Fourthly, our senses, in many cases, bear witness to the truth of each other's report concerning the existence of sensible things without us: he that doubts when he sees a fire, whether it be real, may, if he pleases, feel it too, and by the exqui site pain may be convinced that it is not a bare idea, or phantom."
Dr. Berkeley, on the other hand, con tends, that external bodies have no exist ence but in the mind perceiving them, or that they exist no longer than they are perceived: his principal arguments, which several others, as well as himself, esteem a demonstration of this system, are as follow : " That neither our thoughts, passions, or ideas formed by the imagina tion, exist, without the mind, is allowed ; and that the various sensations impressed on the mind, whatever objects they com pose, cannot exist otherwise than in a mind perceiving them, is equally evident. This appears f'rom the meaning of the term exist, when applied to sensible things : thus, the table I write on exists, i. e. I see and feel it, and were I out of my study I should say it existed, i e that were I in my study I should see and feel it as before. There was an odour, i. e. I smelt it, &c.; but the existence of un thinking beings, without any relation to their being perceived, is unintelligible : their ease is percipi." Then, to skew that the notion of bodies is grounded on the doctrine of abstract ideas, " What," he asks, " are light and colours, heat and cold, extension and figure, in a word, the things we see and feel, but so many sensations, notions, ideas, or impressions on the sense; and is it possible to sepa rate, even in thought, any of these from perception ? The several bodies, then, that compose the frame of the world, have not any subsistence without a mind : their esse is to be perceived or known ; and if they are not perceived by me, nor by any other thinking being, they have no shadow of existence at all: the things we perceive are colour, figure, motion, &c. that is, the ideas of those things; but has an idea any existence out of the mind? To have an idea is the same thing as to perceive ; that, therefore, wherein co lour, figure, &c. exist, must perceive them. It is evident, therefore, that there can be no unthinking substance, or sub stratum of those ideas. But you may ar gue, if the ideas themselves do not exist without the mind, there may be things like them, whereof they are copies or re semblances, which exist without the mind. It is answered, an idea can be like nothing but an idea, a colour or figure can be nothing else but another colour or figure. It may be farther asked, whether those supposed original or external things, whereof our ideas are the pictures, be themselves perceivable or not? If they be not, I appeal to any one, whether it be sense to say a colour is like somewhat which is invisible, hard or soft, like some what (intangible, &c. Some distinguish between primary and secondary quali ties; the former, viz. extension, solidity, figure, motion, res!, and number, have a real existence out of the mind; for the latter, under which come all other sensi ble q :alities, as colours, sounds, tastes, &c tnt y allow the ideas we have of them are not resemblances of any thing with out the mind, or unperceived, but de pend on the size, texture, motion, &c. of the maatte particles of matter. Now it is certain that those primary qualities are inseparably united with the other secon dary ones, and cannot even in thought be absixacted from theni, and therefore must only exist in the mind. Again, great or small, swift or slow, are allowed to exit no where without the mind, be ing merely relative, and changing as the frame or position of the organ changes : the extension, therefore, that exists without the mind is neither great nor small, the motion neither swift nor slow, they are nothing. That number is a creature of the mind is plain, (even though the other qualities were allowed to exist) from this, that the same thing bears a different denomination of number, as the mind views it with different re spects : thus, the same extension is 1, 3, or 36, as the mind considers it, with re. ferenc€ to a yard, a foot, or an inch.