Spinoza defines substance as that which can be conceived solely through itself.

It seems to me that is possible to assume that no idea can ever be conceived solely through itself. For example, a world where everything is a modification of something else.

Why would there necessarily be a bottom? That is, a thing that can only be conceived through itself?

It is possible to argue that space can be divided infinitely. One must then deal with Zeno's paradox of how motion is possible. So, my argument is that material composition (modifications) could also be divided infinitely (that is, each material is a modification of another material ad infinitum). In such a case, substance, by Spinoza's definition, is not necessary.

Does Spinoza ever make an argument similar to Zeno to show the unreasonableness of this assumption? Or does he just assert that eventually, a "bottom" if you will, must be reached.

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    Yes it's possible that materials can be divided infinitely exactly as Leibniz once argued for his rejection of materialism, and today you can even divide in some large cardinal fashion. But who/what really divides if not a substance?... Commented Aug 16, 2022 at 5:17
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    IMO it is not an issue about divisibility. The idea is that we conceive/perceive qualities as aspects that belongs to something. The qualities are accidents while the "bare something" is substance. Commented Aug 16, 2022 at 10:23
  • Thanks for the answers. So, even if reality can be divided up infinitely, the idea of "substance" can still be the "cause" of that infinite divisibility. That makes sense. Thanks. Commented Aug 16, 2022 at 15:26

3 Answers 3


In the first part of ethics, Spinoza demonstrates that what he calls substance englobes in totality everything there is and therefore necessarily exists. Rather than an aspect of reality, it is reality itself.

To him substance is not the bottom idea from which every ideas follow, but the globality of all ideas, as substance is infinite (prop. 8) and whatever is is part of the substance (prop 15). If anything limits the scope of a substance, this substance would have to be conceived through this thing, and would therefore not respect the definition of a substance.

In the same way, if we imagine something is an external cause to a substance, this thing has to be itself part of the substance otherwise it wouldn't be conceivable only through itself. Therefore substance has to be, by its own definition, cause of itself.

By his definition, the inifinite sequence of causes you are describing is all part of substance, which is itself infinite and therefore not a problem.

This demonstration, though, is a form of ontological argument ("I can conceive of a thing that necessarily exist, therefore it necessarily exists") which has its own problems ("if I define A as existent, then A exists" ok, but how can we make sure the definition makes sense in the first place? It sounds more like wishful thinking). But it does not fail because of the regression ad infinitum objection you are rising.


Buddhist metaphysics takes this tack. The notion to look up is pratityasamutpada. It's translated usually as "dependent arising" from pratitya (dependent upon) and samutpada (arising). It means that every dharma (nature) is dependent upin another dharma (nature). Thus every is codependent and there is no ground of being other than the whole itself.

This has been one of the major traditions in the East, and a very minor one in the West. Spinoza, despite his credentials as a radical thinker, was a traditionalist when it came to the primary ontologies in Western metaphysics which is why the very first proposition in his Ethica is:

By that which is self-caused, I mean that of which the essence involves existence, or that of which the nature is only concievable as existent. (Tr. Elwes)

In fact, he adopts thos from Aquinas who actually adopted thos definition from Ibn Sinna.

This is a definition rather than a proposition. Spinoza does not "prove" it as he knows full well that certain things are beyond proof and this goes just as much for ordinary axiomatics as say in Euclidean geometry, where primitives are not proven, but are to be understood as Descartes described as "clear and simple ideas", as it does for his philosophical axiomatics.


Philosophical analysis is not going to tell us which is the solution to this question.

All that analysis ever does is to make conceivable solutions explicit, This produces alternative conclusions the truth of which depends on which premises are true and we don't know that either just by analysis. Analysis is very useful but doesn't say which is the correct possibility.

If reality is not infinitely divisible, we might get close to the "bottom". We are apparently already much closer to the bottom than our unaided sensory perception gets.

If infinity is infinitely divisible, science itself is illusory in that it can only provide a better picture, not even of what the local reality is, but of what it superficially looks like, and then only here and now.

Intuitively, it seems most people go for not infinitely divisible. Yet, even if this is true, it may be much more divisible than we currently think it is. If this is so, then science will keep producing more and more bewildering results. We may end up looking at the division of matter no longer as a quest for pure knowledge than we may believe that it is, but as a sort of necessary journey through the layers of appearances to find with each new layer the ground for perhaps new technological opportunities. But would any sentience have the time and QI to get to the end of this road before the universe folds down one way or this other?

Quantum mechanics seems to suggest a much more simple reality, if simple is the right word. If reality is that simple, the science of it should converge sooner rather than later on a true model of it. Yet, even if it does, we won't know that it will have. We will see that our model works but all that we will be able to infer reasonably is that it has worked all good so far. And analysis won't get us any truer.

More fundamentally, we cannot possibly understand reality. We are only human after all, and we understand reality by explaining something apparently real in terms of something else apparently real. There is by definition nothing else but reality so that there is nothing else we could use to explain reality with. This is what the notion of substance implies. There is nothing to define what it is except itself and so you cannot explain it. Science itself only ever explains one layer of appearances in terms of another layer, hence the idea of an infinite analysis of reality. If there is a last layer, we won't be able to explain it.

Philosophy is all very interesting but we don't spend the money we spend on science to solve philosophical questions. Science is not a quest for knowledge, it is a quest for practical solutions to practical problems. We don't need to know, we just want to survive, and we don't need to know in order to survive. We just need our science to work well enough to help us survive. Science is fundamentally just human rationality, the rationality of everyday life, only done more systematically, more rigorously, with more organisation, with more money, and crucially, with a memory that goes much beyond any human's life span. No wonders that it works and works well, but it is nonetheless not actual knowledge. It is belief which works for what we need.

And so science won't get us to the bottom either. If reality is infinitely divisible, we might get smart enough to do some of the journey and enjoy the show.

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    This does not answer the question about Spinoza.
    – Philip Klöcking
    Commented Aug 16, 2022 at 18:31

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