Thomas Hobbes:

De Corpore

Is physical substance the only kind of substance?

Background

Thomas Hobbes (1588 - 1679) was an English philosopher, who lived at a very turbulent time in English history. From 1642–1651 England was consumed by Civil War. The Parliamentarians (who were against the idea that the King should rule unchecked) fought against the forces loyal to King Charles I. The Parliamentarians won and Charles I was executed.

Hobbes’ philosophy was very very wide-ranging. He wrote about topics as diverse as history, geometry, theology, and politics.

De Corpore was originally intended to be part of a trilogy of works on philosophy. The name translates to On the Body, but is not so much about bodies - as in human bodies, as about bodies as in physical structures in general.

Materialism

Hobbes was a materialist - he didn’t believe that anything else exists except matter. He disagreed with Descartes’ idea that the mind was something separate from the body and existed as a kind of immaterial substance. He had two main arguments against this substance dualism (the belief in two kinds of substance) and in favour of substance monism (the belief in only one kind of substance).

Argument 1: The Mind as a quality of the Body

Thomas Hobbes argued against Descartes’ division of the body and the mind. Descartes thought (as a result of his evil demon thought experiment) that we could imagine a mind as being separate from a body. Hobbes, however, conceived of a mind as being a quality of a body - in the same way that blue might be a quality of a chair. And because the mind is a quality of a body, it can’t exist without the body (or substance). If the body disappears, so does the mind:

But the abuse consists in this, that when some men see that the increases and decreases of quantity, heat, and other accidents can be considered, that is, submitted to reasons, as we say, without consideration of bodies or their subjects (which is called “abstraction” or “existence apart from them”), they talk about accidents as if they could be separated from every body. The gross errors of certain metaphysicians take their origin from this; for from the fact that it is possible to consider thinking without considering body, they infer that there is no need for a thinking body; and from the fact that it is possible to consider quantity without considering body, they also think that quantity can exist without body and body without quantity, so that a quantitative body is made only after quantity has been added to a body. These meaningless vocal sounds, “abstract substances,” “separated essence,” and other similar ones, spring from the same fountain.

—Thomas Hobbes, De Corpore, 3.4

We can summarise the two positions like this:

Descartes’ argument:

If I can imagine one thing without another, then there is a ‘real distinction’ between those things.
E.g. I cannot imagine ‘a triangle’ without imagining ‘a three-sided shape’, so there is not a real distinction between ‘a triangle’ and ‘a three-sided’ shape. But I can imagine ‘a triangle’ without imagining the colour ‘blue’, so there is a real distinction between ‘a triangle’ and ‘a three-sided shape’.
I can imagine ‘a body’ without ‘a mind’
∴ there is a real distinction between those things
If there is a real distinction between two things, one can exist without the other.
∴ the mind can exist without the body

Hobbes’ response:

There is a real distinction between a material substance and a quality, only if you can imagine that quality without any material substance at all.
Even if you can imagine ‘a triangle’ without imagining the colour ‘blue’, that does not mean that you can imagine the colour ‘blue’ without any shape at all. These accidental qualities (like blue) still need a material body to be attached to.
You cannot imagine quality without any material substance
∴ everything depends upon material substances.

Hobbes’ conclusion was that we are nothing but machines.

Argument 2: The concept of Substance Dualism is incoherent

Hobbes’ second argument, which he outlined in another book Leviathan, was that the concept of ‘immaterial substance’ or ‘incorporeal substance’ or anything similar simply didn’t make any sense and was a contradiction in terms - like ‘a four-sided triangle’, or ‘a married bachelor’.

All other names are but insignificant sounds; and those of two sorts. One when they are new, and yet their meaning not explained by definition; whereof there have been abundance coined by schoolmen, and puzzled philosophers.

Another, when men make a name of two names, whose significations are contradictory and inconsistent; as this name, an incorporeal body, or (which is all one) an incorporeal substance, and a great number more. For whensoever any affirmation is false, the two names of which it is composed, put together and made one, signify nothing at all.

—Thomas Hobbes, Leviathan, Chapter 4

(By ‘insignificant’ he doesn’t mean unimportant, he means that it signifies nothing.)

We can summarise his argument like this:

Dualism is correct only if the idea of ‘immaterial substance’ makes sense.
A substance is, by definition, material
∴ the idea of ‘immaterial substance’ doesn’t make sense (are ‘insignificant sounds’)
∴ there is only material substance

Discussion

But let's defend Descartes for a moment. Imagine Descartes is right and we are Non-playable-characters in a computer game. Everything that we see around us would just be code, wouldn't it? And our minds would just be code too, wouldn't they? So aren't they actually just two different kinds of the same thing - code? Viewed in this way, substance is just another word for code.

Is there anything wrong with this argument? If so, what?

Tasks

Explain Hobbes’ response to Descartes’ argument that the mind and body are separate entities.
Explain Hobbes’ argument that the idea of an ‘immaterial substance’ is ‘insignificant’.
What do you think of the idea that we are nothing but machines? Explain your answer.

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