Are there "natural kinds"?

By “elements” do you mean earth, fire, water, air? And if those are natural categories, why do we no longer recognize them as such?

Or do you mean elements such as hydgrogen, helium, etc? If if those are natural categories, why did not Aristotle recognize them as such?

I am underwhelmed by that overwhelming evidence.

It is said that conventions are arbitrary. But arbitrary is not the same as random. There is usually a pragmatic basis to conventions. And, sure, there is a strong pragmatic basis for the categories from physics. But it took centuries of work by pragmatic scientists to come up with those categories. It took a comprehensive education system to socialize people into accepting those categories. And that socializing works by establishing social conventions.

You trivialize all of that work by scientists and educators if you insist that the categories are natural.

1 Like

Why? You seem to be equating “natural” with “self-evident” or “obvious”, and I don’t see the connection.

1 Like

I would be happy to see metaphysics being abandoned, though I expect I would have some disagreements with Quine.

This really comes from my study of consciousness. If categories are fixed external to us, then we are mere mindless mechanical robots and we could not possibly be conscious.

This is why philosophers have problems understanding consciousness. They start with metaphysical assumptions that leave nothing for consciousness to do.

It seems to me that I questioning exactly that. So, no, I am not equating those.

Then I have no idea what you’re saying.

Hi @nwrickert,

By “elements” do you mean earth, fire, water, air? And if those are natural categories, why do we no longer recognize them as such?

Short answer: they can be broken down into other pure substances. Water is H2O, for instance.

Or do you mean elements such as hydrogen, helium, etc? If if those are natural categories, why did not Aristotle recognize them as such?

That’s not really a fair question. The only elements known in antiquity were metals such as gold, silver, tin, copper, lead and mercury. If you look at Lavoisier’s list of elements from 1790, you’ll see that helium is not included. In fact, it wasn’t discovered until 1868. Even hydrogen was only discovered in 1766. Aristotle died in 322 B.C.

You trivialize all of that work by scientists and educators if you insist that the categories are natural.

I’m not sure why you believe this. On a theistic account of Nature, in order to understand natural categories, we have to get inside the mind of God, and “think God’s thoughts after him” (Kepler) - which is by no means an easy thing to do. On a non-theistic account, our minds still have to carve Nature at the joints - a task which they did not evolve to accomplish. On either account, science is a task at which we might well fail, and in which progress is by no means guaranteed.

So you evade that question.

And you evade that.

I asked two contrasting questions, in an attempt to explore what you mean by “natural category”. And you evaded both of them.

The natural world is not homogeneous. Some of the inhomogeneities are sharper than others, but none is completely sharp. We make use of those to pragmatically divide up the world. But, ultimately, it is human pragmatic decision making that we follow.

The border between Illinois and Wisconsin is partly along a river (a natural inhomogeneity) and partly along a straight line (an abstract geometric construction). Clearly, we are not obliged to follow natural inhomogeneities even when they exist. So how we divide up the world can only be a matter of human decision making.

I am questioning whether there are joints. It seems to me that the divisions are all man-made. Yes, we make use of natural features to aid us in our carving up. But it is always a matter of pragmatics. It is not logic applied to already existing “natural” categories.

So you don’t think the boundaries between the elements are completely sharp? Why not? I have difficulty imagining an atom with one-and-a-half protons, for instance.

1 Like

Quantum Mechanics.

If you don’t start seriously engaging with him, I will be very disappointed.

1 Like

I agree, @vjtorley has a point. The boundary between elements is sharp, at least in the normal state of affairs.

That doesn’t mean all concepts have sharp distinctions, but some certainly do.

Care to expand on that? It’s pretty easy to say “quantum mechanics” as if it’s some kind of trump card, but it takes more work than that to demonstrate that it actually supports your position.

Ironically quantum mechanics demonstrates the quantum nature of reality…

It’s a sidetrack.

My main point was not about whether boundaries are sharp. My point was that categories exist because of what we do. There aren’t categories until we start to categorize.

What does quantum mechanics have to do with your point? If the answer is “nothing”, why did you bring it up? You’re being very cryptic, and not just in that instance. This isn’t helping your point, whatever it is.

It is a sidetrack about whether boundaries are sharp. That they are not sharp is illustrated by the Schrödinger’s cat thought experiment.

I think I was clear enough about my point, when I said:

Obviously, people disagree, but seem unable to explain why they disagree.

Perhaps somebody would care to define “natural category”. I won’t attempt that, since I don’t think they could exist. From my point of view, a category is an abstraction. And I don’t see how abstractions could be considered part of nature.

Obviously you weren’t, since nobody seems to have understood your point. This seems to be an argument about what “natural category” means. In other words, it’s a boring controversy over definitions.

This might help:

How does it illustrate that? Particularly when it’s an open question quantum foundations what the Schrodinger’s cat thought experiment actually demonstrates - note its original intent by Schrodinger was to show that quantum mechanics is incomplete, not that cats can actually be both dead and alive at the same time.


It’s a good discussion.

Here’s part:

My take from that, is that there are no natural kinds. How we see the world very much reflects human interests.

I’m suspecting that it is hard to distinguish between what is natural and what is conventional. Somebody growing up in the USA would see that people always drive on the right. That becomes so familiar that it seems natural. Only when they learn that driving habits are different in England or Australia, do the begin to recognize that it is conventional rather than natural.

People describe Newton’s laws as laws of nature. But, for Aristotle, the natural view of motion would have been that moving things naturally slow down. Aristotle would have thought Newton’s laws were obviously false. So perhaps they are more conventional than natural.

And then, as a mathematician, I use the natural numbers. I don’t see that those are really natural at all. I see them as arising from our conventional counting practices.