As usual, substances means the fundamental entities of reality ("the basic things from which everything is constructed" as the Stanford Encyclopedia of Philosophy puts it) in a certain philosophical system.

Or from the shorter routledge encyclopedia of philosophy, article "Substance":

For Aristotle, ‘substances’ are the things which exist in their own right, both the logically ultimate subjects of predication and the ultimate objects of scientific inquiry. They are the unified material objects, as well as the natural stuffs, identifiable in sense-experience, each taken to be a member of a natural species with its ‘form’ and functional essence.

Now, Aristotle assumed humans, animals and even plants to be substances. But an artifact like a mechanical wall clock is not a substance for him.

Obviously, if we inspect a comparatively simple/crude artifact, we may see parts of natural "stuff" like wood or metal which were forced by the artisan(s) into a special shape and then assembled in a certain way (as in said mechanical wall clock).

But what about more sophisticated, modern artifacts? A CPU, for example doesn't show (like a mechanical clock) how it is made from natural materials retaining their structure partly and forced into certain shapes by an artisan. As we all know, the structure of the CPU die is so delicate, it can only be seen under a microscope. And of course, a CPU constitutes one extremely tightly joined, functional unit, a "unified material" object and cannot be disassembled and reassembled again like a mechanical clockwork.

So, wouldn't it be consistent for Aristotle to regard such artifacts like a CPU as substances?


3 Answers 3


Aristotle's views on artifacts are a little bit hard for us to accept in the contemporary era, but the basic idea is that a substance is unified by a single form which is its activity and the thing that organizes it.

So I think it's slightly off to say Aristotle assumed humans, animals and even plants to be substances. On Aristotle's picture, this is not an assumption -- it's an observation from empirical data. To give a couple of examples by differentiation:

  1. A plastic plant and a living plant differ in two significant regards. First, if I snap a branch off the plastic plant, it forever remains damaged in that way. Conversely, if I snap a branch off a living plant, then the plant will either suffer a catastrophic death and stop being a plant (i.e. die) or it will adapt and recover around that and continue its life. In other words, the plant-like artifact just takes damage, but there's no life to take away from it. Second, the real plant is growing and to keeping being a plant needs soil, light, and air.

  2. A taxidermed wolf vs. a dog. We have the same image of damage vs. injury. In addition, the real living animal moves around under its own utility whereas the taxidermed one can't do that. Even if we stick something in it and let it be remote-controlled, then that's not really the taxidermed thing moving around on its own.

To put it another way, a substance has one thing that makes it tick and that orients the rest of what it's doing. And when we break that, for living things we have to kill them, and for other things they completely lose their unifying coherence.

I raise this because the point isn't that Aristotle is pulling a random assumption out of thin air and holding to an irrational faith in substances. At least on his own view, he thinks he's using his mind to intuit forms from living things (and some non-living things).

One contrastive category is the "aggregate" or the "pile." If we think of a mound of sand, it doesn't really have anything that 'unifies' it in a deep sense. There's nothing that keeps the pieces of sand grouped except that they are pieces of sand.

If we think about a CPU, it's really a very well organized aggregate. It's billions of little tiny transistor gates that we've piped together to work out as a super abacus. But it's still a bunch of parts that don't have a fundamental unity or maintain themselves. They have a very useful unity in that we put this tool to good use, but the unity is not fundamental to the thing.

In other words, I deny that a CPU is a "unified material object". The key is to grasp that what is meant her by unity is not "to be in one piece" but rather to be one coherent whole where the parts necessarily compose the whole.

Now, the article Mauro mentions raises some similar objections to what you're raising but does so in the context of a good understanding of the Aristotelian vocabulary and how it works.

If we want to lend credence to your idea, a better example might be an android of some sort. Here, it seems to have internal motion and coherence around its android existence. In other words, it would be better approaching that unity even with non biological parts.

(ps in passing I do want to mention that this is a good question despite my disagreement with your claim -- in large part because Aristotle's view and claim are hard to understand).

  • Hi. Can you add some text references, that show that Aristotle asserted that artificial objects are not substances, and why? Dec 16, 2016 at 6:52
  • 1
    @virmaior is correct. For Aristotle the real dividing line between substance and artifact is whether the object has its own innate principles of change and motion. Substances have characteristic activities in virtue of their forms--living substances live their characteristic lives--spiders spin webs, etc. and inanimate substances have their own characteristic activities--earth moves to the center of the universe, fire to the outer extremes, etc. Artifacts, on the other hand don't have this. Their purposes or activities are extrinsic or imposed. The classic text here is Physics II.1
    – user5172
    Dec 16, 2016 at 14:47

No, Aristotle would not regard an artifact like a CPU as substance because it fails his second test, "ultimate object of scientific inquiry."

The "ultimate object" of a CPU would be the silicon atoms, not the CPU itself.

  • Then why are plants or animals substances? Why are the carbon, hydrogen, oxygen etc. atoms of living beings not the ultimate object of scientific inquiry?
    – viuser
    Dec 14, 2016 at 23:09
  • @wolf-revo-cats Short answer: because plants and animals have properties that are not properties of the elements that make them up. Plants photosynthesize and carbon doesn't. That means there are some phenomena about the plants you wouldn't get, even with an exhaustive description of the carbon, etc.
    – user5172
    Dec 16, 2016 at 14:51
  • 2
    You deny the existence of computer science, which studies CPUs as an "object of scientific inquiry"?
    – Geremia
    Dec 16, 2016 at 16:34
  • @shane: that's true for CPUs, too. A CPU can add numbers, a silicon atom can't.
    – viuser
    Dec 17, 2016 at 1:51
  • @wolf-revo-cats I'm not defending Aristotle's position here necessarily. I think it's safe to say there's a lot of artifacts today that Aristotle would never have dreamt of. But, note that things like the CPU would fail the "having their own internal principles of change and motion" criterion Aristotle gives for something's counting as a substance. I guess the question should become: "Are the different conceptions of substance Aristotle gives, in terms of change and motion and in terms of being the objects of science really compatible?" I don't know the answer to that.
    – user5172
    Dec 17, 2016 at 19:15

Aristotle assumed humans, animals and even plants to be substances.

Yes, because they are beings whose essence naturally requires them to exist in themselves.

an artifact like a mechanical wall clock is not a substance for him.

Artifacts are natural substances with accidental forms. Accidents exist in another, not of themselves. But a clock is not just a form all by itself. Only matter-form composites have existence. So, although a clock has no intrinsic principle urging it to change from non-clock to clock—this accidental form has to come from an extrinsic, efficient cause, e.g., from a clockmaker—a clock is a substance because it is able to preserve its being a clock; it does not corrupt into a non-clock after the clockmaker stopped giving it its accidental form.

Here's what Aristotle says at the beginning of Physics bk. 2:

Of things that exist, some exist by nature, some from other causes. 'By nature' the animals and their parts exist, and the plants and the simple bodies (earth, fire, air, water)—for we say that these and the like exist 'by nature'. All the things mentioned present a feature in which they differ from things which are not constituted by nature. Each of them has within itself a principle of motion and of stationariness (in respect of place, or of growth and decrease, or by way of alteration). On the other hand, a bed and a coat and anything else of that sort, qua receiving these designations i.e. in so far as they are products of art—have no innate impulse to change. But in so far as they happen to be composed of stone or of earth or of a mixture of the two, they do have such an impulse.

Aristotle says artifacts have no intrinsic impulse to change; he does not say artifacts cannot have an intrinsic principle of "stationariness." Artifacts are certainly able to do this, else the Mona Lisa wouldn't still be in the Louve after centuries. But, the matter of the Mona Lisa (the organic canvas, paints, etc.) certainly does tend toward corruption.

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