Lisa asked:

How does Berkeley use Ockham’s Razor against John Locke?

Answer by Geoffrey Klempner

Another student assignment. I am going to make this easier for you, Lisa, by telling you what your teacher wants to hear. Then I am going to give my own view which you are totally free to ignore. In which case you don’t need to read past the third paragraph of my answer.

The story goes like this: In his Essay on Human Understanding, Locke gave an account of the origin of our ‘ideas’ — sense impressions and the concepts based on them — in terms of the interaction of our sense organs with material reality. Bishop Berkeley looked at this and thought, ‘Hmm, I can give just as good an account without positing this extra entity, ‘matter’. No-one ever experiences ‘matter’. All we experience are perceptions. On my theory, all statements about so-called ‘material reality’ are just conditional statements about actual and possible experiences.’

This is a classic example of the application of Ockham’s Razor, ‘Do not multiply theoretical posits unnecessarily.’ According to Berkeley, ‘matter’ is a theoretical posit that we can painlessly dispose of. Conditional statements about possible experiences are the ultimate truth about external reality. Job done.

First, a picky point. When physicists talk about Ockham’s Razor, they tend to mean something else than when a philosopher appeals to this principle. In physics, or science generally, not making unnecessary posits is a constitutive part of the task of constructing the most simple or elegant theory. The most elegant theory can still be false. We can get fooled by reality, things can be more complicated than we assumed, but in the long run we are less likely to be fooled if we follow the rule of preferring simple explanations to those that are unnecessarily complex.

In his Tractatus Logico-Philosophicus, Wittgenstein offers a radically different take:

If a sign is useless, it is meaningless. That is the point of Occam’s maxim.
(If everything behaves as if a sign had meaning, then it does have meaning.)
(Para 3.328)

Occam’s maxim is, of course, not an arbitrary rule, not one that is justified by its success in practice: its point is that unnecessary units in a sign-language mean nothing.
Signs that serve one purpose are logically equivalent, and signs that serve none are logically meaningless.
(Para 5.47321)

On Wittgenstein’s reading, what Berkeley is saying is not, ‘I can give a more elegant theory than Locke.’ Just read Berkeley, and you will see how wrong that is. He repeatedly makes the point that ‘matter’ is a meaningless notion, a horrendous invention of philosophers, while it is plain ‘common sense’ that all we know or can ever think about are our own perceptions.

But here’s the rub: the attempt to reduce statements about the external world to ‘conditional statements about actual and possible experiences’ is a catastrophic failure. (If you’re interested in pursuing this, read Chrisopher Peacocke Holistic Explanation: action, space, interpretation 1977.) Briefly, it is impossible to pin down ‘objects’ because every conditional statement refers to many, many more conditional statements. It’s like trying to solve simultaneous equations with too many unknowns.

I don’t think Berkeley thought the matter through to this point. It’s difficult when the only logic you know is the logic of Aristotle. However, what he did realize is that there is something fundamentally wrong with the notion that conditional statements can represent the ultimate truth about anything. A conditional needs a truth maker, a non-conditional fact in virtue of which the conditional statement is true. (If you’re inclined to doubt this, try it for yourself. Imagine that some conditional statement is ‘in fact’ the case, but there is no further non-conditional fact that accounts for its truth.)

Berkeley saw this quite clearly: his response was all our perceptions are ultimately explained by the virtual reality blueprint in the mind of God. My answer has already been long enough, so I won’t explore this aspect of Berkeley further. (Do a search, this is a topic that has come up before on Ask a Philosopher.)

So, we threw out matter and brought in… God?

Ockham’s Razor?!