This is the first in a series of posts about two Early Modern Philosophers* (EMPs) called Benedict Spinoza and Gottfried Leibniz. Sometimes reading Spinoza and Leibniz, one is struck by a powerful feeling: what the hell are these guys doing? Why do I care?
They seem to take some arbitrarily defined notion of ‘substance’ and then prove from it and various other implausible assumptions that everything you think is wrong, and that the truth about the world is something somewhat bizarre.
To make it worse, they seem to make very similar implausible assumptions, and then deduce apparently opposite conclusions. WTF, mate?
So in this post I want to try and put them in a context where their metaphysical craziness not only seems understandable, but moreover teaches us something actually relevant.
(this is another post liable to be mostly of interest to students of philosophy).
The broadest context for these two, and Early Modern Western Philosophy, is science. Science has appeared, along with capitalism, individualism, freedom of criticism, and philosophy is trying to come to terms with this, to express the scientific enterprise in an intellectually coherent way.
The scientific enterprise, however, cannot be coherently expressed on its own, and this is reflected by the division of EMPs into rationalists and empiricists.
The latter (typically considered to be Locke, Berkeley, and Hume) take one side of science, the idea of the absolute authority of the data, that everything must be justified by reference to experience. Nothing can just be known to be true – there has to be something we can point to and say “when I saw this, it showed me”.
The former (typically considered to include Descartes, Spinoza, and Leibniz) take the other side of science, the fact that science as a practice and a method is constructed by certain principles that cannot themselves be drawn from experience. A key example is the ‘Principle of Sufficient Reason’: nothing happens without a reason, for every truth there is an explanation.
This reflects a guiding methodological principle of science, to always look for an explanation of whatever happens – but why does it make sense to do that? Why expect that things will have explanations to find? That can’t itself be something we found out from the data, because it tells us what to do with the data.
So that’s the first thing to bear in mind with Spinoza and Leibniz: they are trying to articulate the vision of what the universe would look like for science to make sense.
But let’s get a bit more specific, and see why they get so hot and bothered over the idea of “substance”? We might get a sense of the problem by asking – what is stuff? This stuff all around us, what is it? What does science say it is? What is mass? What is (to step a little further on from the EMPs’ period) charge, spin, force, energy, etc?
In the science of Newton and the other early moderns, there’s a conception we are probably fairly familiar with – stuff is particles. Stuff is empty space, but filled with billions of tiny things flying around. But that just pushes the question onto ‘what are particles?’ Well, they’re tiny bits of, um…stuff. We imagine little beads, right, little hard smooth spheres?
We have no reason to think that they’re any particular shape (they might be shaped like a rude body part for all we know) but let’s run with this image of the little beads. We can at least say that these are spherical, they have a boundary that we can describe geometrically – we have a pretty good concept of geometry, of shapes. But what is the difference between one side of the boundary and the other? What is it that’s ‘inside’ the sphere, as opposed to the ’empty’ space outside?
We can certainly say what it ‘does’ – it repels other particles (but what are they?) and it attracts other particles, and under the right circumstances it produces certain sorts of perceptions in us. But that’s hardly an answer to ‘what is it?’
What we naturally say is, what’s on the inside of the sphere is ‘substance’, or ‘matter’. Observe what this idea of substance amounts to – it seems to be both ‘a priori’ (i.e. we haven’t drawn it from perception, we have it innately) and perhaps primitive (can’t be defined in terms of anything else).
I would argue – perhaps readers disagree – that this idea of substance is all that keeps science realist. That is, without it, we have to understand science as telling us merely how our perceptions are arranged, when to expect to see or feel something, not what things actually are. Science doesn’t say anything about what things are, because its ideas are drawn from experience, and experience is a relationship between us and things. Things no doubt still exist, but in a somewhat mysterious way.
So substance is quite an important idea here. Substance, the idea of stuff or matter, is central to the scientific worldview, because without it, science doesn’t give us a worldview, just an account of how we perceive the world. But if we can’t define or express what we mean by substance, then…well, perhaps that is an acceptable position: substance is indefinable, but we should still believe the world to be full of it.
But the point is, Spinoza and Descartes and Leibniz, they don’t consider that adequate. They feel like we can only use this vital concept is we can define it. That’s not clearly unreasonable. But when they try to do that, things get incredibly hairy, as I’ll discuss in part 2.
*’Early Modern’ refers to European thinkers of the 17th and 18th centuries – prominent figures include Descartes, who is often seen as the starter of the period, Hobbes, Locke, Spinoza, Leibniz, Berkeley, Hume, and the super-dude who wrapped things up, Kant.