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Spinoza's proof of the existence of God as the sole substance


To: Yasuko S.
From: Geoffrey Klempner
Subject: Spinoza's proof of the existence of God as the sole substance
Date: 13 April 2007 11:23

Dear Yasuko,

Thank you for your email of 7 April, with your University of London essay in response to the question, 'Does Spinoza succeed in proving both that God exists, and that no substance apart from God exists?'

If I was answering this question, I would make the point that the actual existence of God follows logically from the proposition that no substance apart from God exists, together with the incontestable premiss that something exists, e.g. my finger. If my finger exists, and no substance apart from God exists, then my finger must be an 'affection' of God. What Spinoza's deployment of the ontological argument is meant to demonstrate is that God exists necessarily and not merely as a matter of contingent fact. There is no possible world where God does not exist. On the other hand, if one takes the more conventional theistic view that substances like my finger can exist apart from the existence God, then the ontological argument (or a suitable alternative) would be needed to establish that God does, in fact, exist.

You have fulfilled at least one of the main requirements for a good essay in response to this question. In this particular case, I don't think that it is an objection, as you worried, that much of the wording is from the 'Ethics'. Spinoza expresses himself clearly and succinctly, and it is difficult to find better ways to say what he says. What you can do, however, is give more explanation of how the argument works by spelling things out. Even if you can see for yourself why a particular inference is valid, it is still worth while to state the obvious. Imagine a reader who is not quite as clever as you are, who needs a bit more help. The slightly stupid reader's objections may seem clearly wrong to you but the rebuttal of those objections will still be very instructive and demonstrate your sure grasp of the argument.

For example, in stating Spinoza's claim that two substances cannot be distinguished by their affections, you say, 'Also, he defines the affections of substance as what owe their nature and being to the substance in which they inhere; accordingly he disregards its affections as the way to distinguish any substances.'

Perhaps this just seems obvious to you, but I can imagine a (slightly stupid) reader raising the following objection. Take any two objects which one might describe as 'substances' in which various qualities or affections inhere. A red ball and a blue ball. Or a pyramid and a cube. I tell you to 'bring me the red ball' and you are able distinguish between the balls by means of the affection 'red'. Or I tell you to 'bring me the cube' and you distinguish between the two objects by means of the affection, 'cubical'.

The answer to this is that for Spinoza, the question of how substances are 'distinguished' is not a matter of how we actually succeed in discriminating between one thing and another, but rather a logical question concerning what it is that constitutes the identity of a given object. In giving the example of a red ball and a blue ball, I am assuming that we already have two 'distinguished' objects in Spinoza's sense, so that the difference in colour cannot be what logically distinguishes them. Rather, the possibility of having different colours follows from the two objects being distinct.

You do in fact attempt an objection to Spinoza and also a reply to that objection, which is the other main requirement for a good answer to this question.

You say, 'We can imagine the case in which substances might share one but not all their attributes. Then substances sharing the same attribute could be distinguished by attributes they did not share.'

Let's try to spell out this objection. As you say earlier, Spinoza 'defines attribute as simply a way of conceiving the essence or nature of a substance'. A substance by definition has one and only one essence, while there may be more than one way of conceiving of this essence. Imagine a world where there are three substances X, Y and Z. X has attributes A and B, Y has attribute A but not attribute B, while Z has attribute B but not attribute A. If attributes A and B are both ways of conceiving the essence of X, how is it possible that Y and Z could differ in this respect?

A concrete example would be where X is a substance with dual aspects of the mental and material, while Y is only material and Z is only mental. What reply would Spinoza make to this proposal?

Let's get more concrete still. Suppose you are arguing with someone who believes in the existence of non-physical souls. However, this person accepts that the physical mental states of living human beings are merely aspects of one and the same substantial entity, say, the brain. So we have a universe where some mental states have a physical basis, while other mental states - those belonging to non-physical souls - do not have a physical basis. Does that make sense in Spinoza's terms? If not, why not?

The reply which you make to the objection raised is based on Spinoza's deployment of the ontological argument for the existence of God. However, this only shows that there cannot be several substances which possess NECESSARY existence, while the objection was to the earlier proof that only one substance ACTUALLY exists. So the reply does not constitute a response to the objection.

One final, picky point. I agree with you about the vision that Spinoza was striving to express, of a universe consisting of a unified system of material substances. However, the particular example which you give of the transformations of hydrogen and oxygen is anachronistic: the theory that the constant ratios of chemical reactions are explained by the combinations of atoms in molecules, such as H20 was put forward by John Dalton in 1800, long after Spinoza's death.

You gain credit or the competent way in which you lay out Spinoza's argument, but lose marks for failing to give a relevant response to the objection which you yourself raised.

The main thing I would like you to think about is what I discussed earlier - the need to spell things out, even when they seem 'obvious'.

All the best,