- WE divide substance first into REAL ESSENCE and NOMINAL ESSENCE.
- The REAL ESSENCE of a substance is unknowable because our mind’s activities cannot penetrate it (The mind is a self-enclosed immaterial entity capable of no knowledge of anything but itself and its own ideas).
- All the ideas we have of the essence of a substance are not ideas about its REAL ESSENCE but only of its NOMINAL ESSENCE.
- For, since the powers or qualities that are observable by us are not the real essence of that substance, but depend on it, and flow from it, any collection whatsoever of those qualities cannot be the real essence of that thing. 2.31.13
- REAL ESSENCE and NOMINAL ESSENCE are easily confused. When we talk about “the essence of something”, we mean only its NOMINAL ESSENCE.
- REAL ESSENCE remains forever unknown: we cannot think about it; we cannot talk about it; because, by definition, we can only think and talk about our ideas of substance, not about substance itself.
Our ideas about the NOMINAL ESSENCE of a substance fall into two kinds:
i) ideas about the PRIMARY QUALITIES of the essence of an object,
ii) ideas about the SECONDARY QUALITIES of the essence of an object.
- PRIMARY QUALITIES include ideas such as solidity, extension, termination of solidity and extension, figure, number, rest, motion etc.
- PRIMARY QUALITIES are ideas about the properties of a thing independent of any observer. Even if no one sees the object, it contains those qualities.
- Solidity and extension and the termination of it, figure, with motion and rest, whereof we have the ideas, would be really in the world as they are, whether there were any sensible being to perceive them or no, 2.31.2
- PRIMARY QUALITIES are ideas of an object which are independent of perception.
- PRIMARY QUALITIES are not subject to change. Dividing an object in half does not disturb the PRIMARY QUALITIES. (size is not a primary quality, it is an idea of relation: size relative to what?)
- PRIMARY QUALITIES are ideas which we imagine to resemble real properties in real objects.
- SECONDARY QUALITIES include ideas such as colour, taste, shape etc.
- SECONDARY QUALITIES are ideas about our perception of a thing.
- SECONDARY QUALITIES are ideas based on the ideas of the PRIMARY QUALITIES
- The interaction of the ideas of the PRIMARY QUALITIES of an object produce ideas of the SECONDARY QUALITIES of an object.
- If sugar produce in us the ideas which we call whiteness and sweetness, we are sure there is a power in sugar to produce those ideas in our minds, or else they could not have been produced by it. 2.31.2
- SECONDARY QUALITIES do not reside in the object, but only in the mind of the perceiver.
- SECONDARY QUALITIES are subject to change. Pounding an almond changes its colour and taste.
- Both PRIMARY QUALITIES and SECONDARY QUALITIES are SIMPLE IDEAS because they are not constructed by the mind out of mental material, but rather arise in the mind through the action of a power residing in the object to produce the idea in the mind.
- It alters not the nature of our simple ideas whether we think that the idea of blue be in the violet itself, or in our mind only, and only the power of producing it by the texture of its parts, reflecting the particles of light after a certain manner, to be in the violet itself. 2.32.14
- Because the mind does not construct them, it is reasonable to suppose that they must therefore be produced by a power coming from the object .
- SOME commentators interpret this thus:
- QUALITIES refers both to qualities that reside in the object itself AND our ideas about those qualities.
- This reading is based on Book 2 Chapter 8.8, where Locke seems to imply that qualities are real properties residing in the object that have the power to produce ideas of those qualities in the mind.
- Whatsoever the mind perceives in itself, or is the immediate object of perception, thought, or understanding, that I call idea; and the power to produce any idea in our mind, I call quality of the subject wherein that power is.
- But this is to overlook Locke’s insistence that the mind cannot know anything outside itself.
- But this is to overlook Locke’s insistence on the distinction between real and nominal essence.
- But this is to overlook’s Locke’s insistence that any discussion of substance is not a discussion about substance per se, but only about our ideas of substance.
- The essence of each sort of substance is our abstract idea to which the name is annexed.3.6.2
- So is Locke talking about substance or about our ideas of substance?
- In what way is Locke an empiricist if we cannot know the real essence of something, if our understanding of substances is limited to the ideas we have of those substances, not the substances themselves?
- There are two ways in which Locke can be regarded as an empiricist, his skepticism about the possibility of understanding the real world notwithstanding.
- First, his empiricism is not directed towards the world of substance and particulars.
- His empiricism is directed towards the mind, its contents, its operations and the extent and limitations of its knowledge about the world and knowledge about itself.
- It is the mind that is the object of observation.
- It’s in this sense that he is an empiricist.
- Newton’s empiricism is directed towards the world, as is Boyle’s. Locke’s is directed towards the mind.
- Second, Locke’s insistence that each man can observe the processes he describes for himself in his mind is empiricist.
- His emphasis on practical experience rather than taking things on trust from an already established authority is empiricist.
- The best way to come to truth being to examine things as really they are, and not conclude they are as we fancy of ourselves or have been taught by others to imagine. 2.11.15