What are Bodies?

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An initially appealing view about bodies is that they are volumes of solidity. However, this position was criticized by Hume on the grounds that it defines bodies as volumes of impenetrability by other bodies, which is circular.

We might think of bodies next as powers to produce certain effects. This is subject to a similar criticism, however, since this would imply that the effects produced are also powers. Powers end up being powers to produce powers which produce powers… and so on forever.

Howard Robinson argues that this should lead us to embrace idealism in his entry on idealism in the Oxford Handbook of Philosophy of Mind (p. 192).

If the physical realist is committed to the powers conception of matter, and if that conception is radically defective, then the physical realist is in trouble. Furthermore, his opponent will point out that, if the pure-powers conception is vicious, then the powers that are supposed to constitute matter must produce something which is not itself a power, but a monadic quality. And such qualities are to be found as sensible qualities in the sense fields of perceivers. So the physical world is a structured capacity to give rise to experience, and this is an idealist conception.

My inclination would be to say that just because we don’t know what bodies are does not mean that we should leap to idealism as an explanation. Maybe there is a better account of what bodies are that Robinson has not considered. Robinson might be sympathetic to this criticism, since he describes this reasoning as “slightly too swift” in a footnote to the quoted passage, and refers the reader to a book of his.



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I just finished reading the entry about property physicalism in The Oxford Handbook of Philosophy of Mind, which was written by Ansgar Beckermann. Over the course of the article, he presents the idea of “emergent properties,” makes reference to “reduction” several times, and considers the view that some emergent properties may be irreducible.

Here are his examples of uncontroversial emergent properties:

  • Solidity and fluidity – “Atoms are neither solid nor fluid; only collections of molecules have these properties.”
  • Breathing, feeding, and reproduction – “Molecules again don’t breath or nourish, nor do they reproduce; only living beings have these capacities.”

Beckermann then introduces the unity of the world thesis and gives examples.

The idea of the unity of the world just consists in the claim that all properties of higher level entities have a reductive explanation in terms of the properties and the arrangement of their lower level parts. That salt is water-soluble has an explanation in terms of the properties of ions that salt molecules consist of. That soap has the capacity to loosen dirt can be explained by its molecular structure. That animals have the capacity to digest has a chemico-physiological explanation, etc. It is, of course, an empirical question whether all higher-order phenomena can be explained in this way. The unity-of-the-world thesis is not a priori true. But it seems to be an aim of science to show that it is an empirical truth.

The other point of interest in this article is his description of the contrast to the unity of the world thesis.

Why is salt water-soluble? To answer this question,it will not do to just point to the fact that water has a certain molecular structure. Nothing short of a reductive explanation will suffice. One has to show that having this molecular structure explains water-solubility. If such an explanation can be given, everything is all right. The thesis of the unity of nature once more is proven to be true. If not, there would be, at this point at least, a breach in nature, as it were. The water-solubility of salt would be revealed to be an emergent property – a real new property with effects that cannot be accounted for by the microstructure of salt.

This seems like a useful way of framing the debate over whether there are emergent properties or whether everything can be reduced to physics and chemistry. Yet I wonder why Beckermann assumes that an emergent property would have to be “a breach in nature,” i.e., supernatural. It seems like there should be some third option between naturalistic reductionism and supernaturalistic emergentism.

Argument Against a Completely Immaterial Mind

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I thought of this argument against the existence of a completely immaterial mind, i.e., a mind that contains no material element. It’s based on a passage in Plato’s Republic.

1. The mind can come into conflict with itself (e.g., when making an important decision).
2. What can come into conflict with itself has parts.
3. What has parts is at least partly composed of matter.
4. Therefore, the mind is at least partly composed of matter.

This is actually consistent with Christian theology, since the Christian can say that the mind has a material part right now, the body, but that the soul will eventually separate from the body in the afterlife and be free of internal conflict. It makes sense that the Christian is able to say this, too, since Plato was the ultimate inspiration for the Christian doctrine of the afterlife (or at least part of its inspiration). I’m posting this because it’s a cool line of reasoning that highlights the fact that Christianity’s dualism is limited in some respects.

A Priori and A Posteriori Identity Theorists

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As I mentioned in my last post, some philosophers are identity theorists, that is, they hold that every type of mental state is identical to a specific type of physical state. For example, they might hold that pain is identical to C-fiber stimulation.

Any identity theorist is committed to the claim that every type of mental state is necessarily a specific type of physical state. However, there can still be debate about what kind of necessity this is. Some forms of necessity seem to be a priori, like 1+1=2, and some seem to be a posteriori, like the fact that water is necessarily H2O. So, which kind of necessity holds of the connection between mental and physical states?

The issue might at first seem easy to decide, since “mental states are necessarily physical states” is not just blindingly obvious from the concepts involved like 1+1=2. However, the issue is not whether the necessity of identity theory is obvious to us right now, but whether it would be obvious if we had all of the physical facts available to us. If we had to do more research to find out whether mental states were necessarily physical states at that point, then identity theory would be necessary a posteriori, and if we did not have to do any more research, then identity theory would be necessary a priori.

The a priori side has to defend the counterintuitive claim that it could just be obvious that mental states are physical states given enough information. The a posteriori side also has problems, since it’s not clear what sort of further research we could do if we already had all of the physical facts in our possession.

So, there appear to be three options:

  1. Don’t accept identity theory.
  2. Accept identity theory as necessary a priori and explain how it could just be obvious that mental states are physical states given enough information.
  3. Accept identity theory as necessary a posteriori and explain what sort of further research we could do after obtaining all of the physical facts.

My inclination is to say that the a priori side has a more plausible position than the a posteriori side, but I’m not an identity theorist.

The Multiple Realizability Argument

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Some philosophers hold to the identity theory of mind, which says that each type of brain state is identical to a type of mental state. For example, pain must be identical to something like C-fiber stimulation if the identity theory is correct.

According to Putnam’s multiple realizability argument, this can’t quite be correct, because the same mental state can be experienced by two beings with different physical constitutions. The Internet Encyclopedia of Philosophy puts the multiple realizability argument like this:

(1) according to the Mind-Brain Type Identity theorist (at least post-Armstrong), for every mental state there is a unique physical-chemical state of the brain such that a life-form can be in that mental state if and only if it is in that physical state. (2) It seems quite plausible to hold, as an empirical hypothesis, that physically possible life-forms can be in the same mental state without having brains in the same unique physical-chemical state. (3) Therefore, it is highly unlikely that the Mind-Brain Type Identity theorist is correct.

There are various ways of handling this objection. For example, one could take the functionalist view that it is the functional role of a brain state within the system of brain states that makes it a specific mental state. You don’t even have to reject the identity theory to handle the multiple realizability argument if you weaken the theory to say that each individual mental state is a specific, individual brain state rather than articulating it in terms of types, as I did above.

An Introduction to Slavoj Zizek

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I don’t know anything about Zizek beyond this video, but he seems like an interesting thinker.

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