The Philosophy of Spinoza by Benedictus de Spinoza (e textbook reader .txt) 📕

[17] From a letter to Henry Oldenburg (1665).

CHAPTER X THE NATURE AND EXTENT OF HUMAN KNOWLEDGE Of Truth

All the ideas which are in God always agree with those things of which they are the ideas. Therefore, all ideas, in so far as they are related to God, are true.

A true idea[18] (for we possess a true idea) is something different from its correlate (ideatum); thus a circle is different from the idea of a circle. The idea of a circle is not something having a circumference and a center, as a circle has; nor is the idea of a body that body itself. Now, as it is something different from its correlate, it is capable of being understood through itself; in other words, the idea, in so far as its actual essence (essentia formalis) is concerned, may be the subject of another subjective essence. And, again, this second subjective essence will, regarded in itself, be something real and capable of being understood; and so on indefinitely. For instance, the man Peter is something real; the true idea of Peter is the reality of Peter represented subjectively, and is in itself something real, and quite distinct from the actual Peter. Now, as this true idea of Peter is in itself something real, and has its own individual existence, it will also be capable of being understood—that is, of being the subject of another idea which will contain by representation all that the idea of Peter contains actually. And, again, this idea of the idea of Peter has its own individuality, which may become the subject of yet another idea; and so on indefinitely. This every one may make trial of for himself, by reflecting that he knows what Peter is, and also knows that he knows, and further knows that he knows that he knows, etc. Hence, it is plain that, in order to understand the actual Peter, it is not necessary first to understand the idea of Peter, and still less the idea of the idea of Peter. This is the same as saying that in order to know, there is no need to know that we know, much less to know that we know that we know. This is no more necessary than to know the nature of a circle before knowing the nature of a triangle. But with these ideas the contrary is the case; for in order to know that I know, I must first know. Hence it is clear that certainty is nothing else than the subjective essence of a thing: in other words, the mode in which we perceive an actual reality is certainty. Further, it is also evident that for the certitude of truth no further sign is necessary beyond the possession of a true idea; for, as I have shown, it is not necessary to know that we know that we know....

He who has a true idea knows at the same time that he has a true idea, nor can he doubt the truth of the thing. For no one who has a true idea is ignorant that a true idea involves the highest certitude; to have a true idea signifying just this, to know a thing perfectly or as well as possible. No one, in fact, can doubt this, unless he supposes an idea to be something dumb, like a picture on a tablet, instead of being a mode of thought, that is to say, intelligence itself. Moreover, I ask who can know that he understands a thing unless he first of all understands that thing? that is to say, who can know that he is certain of anything unless he is first of all certain of that thing? Then, again, what can be clearer or more certain than a true idea as the standard of truth? Just as light reveals both itself and the darkness, so truth is the standard of itself and of the false.

Of Falsity

There is nothing positive in ideas which can constitute a form of falsity. But falsity cannot consist in absolute privation (for we say that minds and not bodies err and are mistaken); nor can it consist in absolute ignorance, for to be ignorant and to be in error are different. Falsehood, therefore, consists in the privation of knowledge which is involved by inadequate knowledge of things or by inadequate and confused ideas. For instance, men are deceived because they think themselves free, and the sole reason for thinking so is that they are conscious of their own actions, and ignorant of the causes by which those actions are determined. Their idea of liberty therefore is this—that they know no cause for their own actions; for as to saying that their actions depend upon their will, these are words to which no idea is attached. What the will is, and in what manner it moves the body, every one is ignorant, for those who pretend otherwise, and devise seats and dwelling-places of the soul, usually excite our laughter or disgust. Just in the same manner, when we look at the sun, we imagine its distance from us to be about 200 feet; the error not consisting solely in the imagination, but arising from our not knowing what the true distance is when we imagine, and what are the causes of our imagination. For although we may afterwards know that the sun is more than 600 diameters of the earth distant from us, we still imagine it near us, since we imagine it to be so near, not because we are ignorant of its true distance, but because a modification of our body involves the essence of the sun, in so far as our body itself is affected by it.

The Origin and Nature of Confused Ideas

The ideas of the modifications of the human body involve the nature both of external bodies and of the human body itself and must involve the nature not only of the human body, but of its parts, for the modifications are ways in which the parts of the human body, and consequently the whole body, are affected. But an adequate knowledge of external bodies and of the parts composing the human body does not exist in God in so far as He is considered as affected by the human mind, but in so far as He is affected by other ideas. These ideas of modifications, therefore, in so far as they are related to the human mind alone, are like conclusions without premises, that is to say, as is self-evident, they are confused ideas.

The idea which forms the nature of the mind is demonstrated in the same way not to be clear and distinct when considered in itself. So also with the idea of the human mind, and the ideas of the ideas of the modifications of the human body, in so far as they are related to the mind alone, as every one may easily see.

All ideas are in God and in so far as they are related to God are true and adequate. No ideas, therefore, are inadequate or confused unless in so far as they are related to the individual mind of some person. All ideas, therefore, both adequate and inadequate, follow by the same necessity.

The Origin and Nature of Adequate Ideas

Let there be something, A, which is common to all bodies, and which is equally in the part of each body and in the whole. I say that A can only be adequately conceived. For the idea of A will necessarily be adequate in God, both in so far as He has the idea of the human body and in so far as He has the idea of its modifications, which involve the nature of the human body, and partly also the nature of external bodies; that is to say, this idea will necessarily be adequate in God in so far as He constitutes the human mind, or in so far as He has ideas which are in the human mind. The mind, therefore, necessarily perceives A adequately, both in so far as it perceives itself or its own or any external body; nor can A be conceived in any other manner.

Hence it follows that some ideas or notions exist which are common to all men, for all bodies agree in some things, which must be adequately, that is to say, clearly and distinctly, perceived by all.

Hence it follows also that the more things the body has in common with other bodies, the more things will the mind be adapted to perceive.

Those ideas are also adequate which follow in the mind from ideas which are adequate in it. For when we say that an idea follows in the human mind from ideas which are adequate in it, we do but say that in the divine intellect itself an idea exists of which God is the cause, not in so far as He is infinite, nor in so far as He is affected by the ideas of a multitude of individual things, but in so far only as He constitutes the essence of the human mind.

I have thus explained the origin of those notions which are called common, and which are the foundations of our reasoning; but of some axioms or notions other causes exist which it would be advantageous to explain by our method, for we should thus be able to distinguish those notions which are more useful than others, and those which are scarcely of any use; those which are common; those which are clear and distinct only to those persons who do not suffer from prejudice; and, finally, those which are ill-founded. Moreover, it would be manifest whence these notions which are called second, and consequently the axioms founded upon them, have taken their origin, and other things, too, would be explained which I have thought about at different times. Since, however, I have set apart this subject for another treatise, and because I do not wish to create disgust with excessive prolixity, I have determined to pass by these matters here.

But not to omit anything which is necessary for us to know, I will briefly give the causes from which terms called Transcendental, such as Being, Thing, Something, have taken their origin. These terms have arisen because the human body, inasmuch as it is limited, can form distinctly in itself a certain number only of images at once. If this number be exceeded, the images will become confused; and if the number of images which the body is able to form distinctly be greatly exceeded, they will all run one into another. Since this is so, it is clear that in proportion to the number of images which can be formed at the same time in the body will be the number of bodies which the human mind can imagine at the same time. If the images in the body, therefore, are all confused, the mind will confusedly imagine all the bodies without distinguishing the one from the other, and will include them all, as it were, under one attribute, that of being or thing.

The same confusion may also be caused by lack of uniform force in the images and from other analogous causes, which there is no need to discuss here, the consideration of one cause being sufficient for the purpose we have