Julian asked:

Is the mind physically real?

and Brandon asked:

If a non-physical entity, such as the wind and a solid object, a tree, interact, wouldn't this go against
the criticism that the 'soul', being non-physical cannot interact with body?

============

Seizing on your tree example, lets try a thought experiment. The process of photosynthesis requires
chlorophyll found in the leaves of trees in order to occur. A chemist can distil chlorophyll quite easily
and put it in a test tube for tests. But ask a chemist to distil photosynthesis and he would just look at
you blankly. Clearly one should not conclude from this that photosynthesis is non-physical however.

Most philosophers and scientists hold that the mind depends on physical processes in the brain in
order for there to be thoughts. So there are causal relations between physical states and mental
states, even if some physical state is not logically identical with some mental state. Just because
minds (like photosynthesis) cannot be plucked out and isolated from their physical supports is not an
argument for showing that minds (and photosynthesis) are non physical, and are thus separable from
bodies. It just shows that we're asking the wrong kinds of questions.

Adam Gatward

I assume, Brandon, that you do know that the wind is physical, that is to say, that it is composed of
material entities, molecules of oxygen, nitrogen etc. whose rapid movement accounts for the pressure
that we feel when the wind blows in our face. (I might conceivably be wrong about this assumption. It
is possible that you missed out on science in school. This is nothing to be ashamed about. The best
remedy is go to a library or bookshop and learn up on some elementary physics.)

Given that you do know what wind is, I take it that what you are saying is, 'Why can't the soul be like
the wind?' You cannot touch or catch the soul, just as you cannot touch or catch the wind, but it
nevertheless is able to bring about effects on more massive objects such as trees or people.

This is a view which was apparently held by the Ancient Greek materialist, Democritus, who first
proposed a version of the atomic theory:

"Some say that the soul moves the body in which it is found in the same way as it moves itself,
Democritus, for example, whose view is similar to what we find in Philippos the comic poet. He says
that Daedalus made the wooden statue of Aphrodite move by pouring quicksilver into it. Democritus
speaks similarly, since he says that moving spherical atoms, whose nature is never to stay still, draw
the entire body along with them and move it. But we will ask if these same things also produce rest.
How they will do so is difficult or impossible to state. In general, the soul does not appear to move the
body in this way, but through choice of some kind and through thought."

Richard McKirahan Jr. Philosophy Before Socrates1994 § 16.46, p.330.

Aristotle's sneering criticism of Democritus which McKirahan quotes seems less than convincing.
Granted that the soul moves the body 'through thought and choice', the question is whether thought
and choice might be, in their underlying nature, perpetually moving atoms. Nor are we convinced by
the argument that moving atoms could not bring about a state of rest. A glider can hover, motionless,
on an updraft of air.

However, this completely misses the target so far as the mind-body interactionism of Descartes is
concerned. Descartes made it quite clear in the Meditationsthat the soul as he understood it was not
'a wind or vapour'. The essence of the soul is completely different from the essence of matter. The
soul has no material properties: no mass, no size, no location in space. I have discussed elsewhere
on these pages how Descartes attempted to account for mind-body interaction. The example of the
wind and the tree is not one that he would have found helpful.

Geoffrey Klempner