John,

My initial question goes to traditional dualism that holds Cartesian categories of mental vs. Physical as totally separate from each other (for example in Searle's book "Mind a brief introduction", p.145-147) and which I think today is still held as a valid philosophical posture (even though Searle and other philosophers point that there is a contradiction there, it is a common view of mathematicians that there is such concept as an abstract line that exists without its physical counterpart).

I guess that the posture brings more questions that it answers to me. For example:

* if I create a memory allocation algorithm can it be considered an algorithm even though I have not tested it on a computer, and I cannot guarantee that it runs (does it have a Platonistic existence like say the laws of Newton)? If not, when does it gain Platonistic existence? And if yes, why would it even be considered an algorithm when it may be wrong? Do memory allocation algorithms even have a Platonistic existence or have the same order, as say the perfect straight line?

*How does my thinking of a memory allocation influences my mind.? would my thinking it entail a "simulation" and how can it be vinculated to my energy expenditure by neuron firing (is there an extra "tax" for my "simulation")?

The short answer is "It doesn't." If dualism is true, the conservation of energy may be false. However, one standard way out of this rather serious problem is called "neutral monism." This view holds that there is really only 1 substance (let's suppose it is information, which is a suggestion David Chalmers makes). This 1 substance has two aspects: a physical aspect and a non-physical aspect. The only thing that is actually dynamically changing is the 1 substance. Its 2 aspects just mirror one another. So, the physical and non-physical (consciousness) stay in sync b/c they are basically mirror images of each other.

Eric, when you speak of two aspects, do you mean two separate domains of description?

Arnold, Yes, in this sense: the two aspects are two different kinds of properties. So, there is really only 1 thing, but it occurs with 2 properties. By way of contrast: Spinoza here disagreed, arguing that the 1 thing had an infinite number of properties, but we can only come into contact with 2 of them.

Eric,

Wouldn't that argument just reduce dualism to a mere semantic (here semantics is used informally) distinction?

Descartes splitted the world between what can be explained mechanically (efficient cause, cause and effect, all that can be described in space) and what cannot be explained deterministically and he identified human Mind as this kind of irreductible entity; After 400 years of scientific advances, it is not clear that the cartesian scientific method can explain consciousness in principle. Quantum theory has already set a limit to the method in the quantum domain.

The problem here is really just that contemporary philosophers do not bother to find out the detail of what they are constructing clever arguments about. This is a classic example of Chinese whispers in which the original formulation has got completely lost.

Leibniz wanted to go one better than Descartes. Descartes had suggested that motion was conserved but Leibniz showed that it must be momentum (directional) that is conserved. Leibniz claimed that Descartes's immaterial mind could not cause matter to 'swerve' because this would violate conservation of momentum (not energy). But Leibniz was wrong because if the mind caused an equal amount of matter to swerve to the right as to swerve to the left, momentum could be conserved. And causing swerving need not involve any work (energy) so that is not a problem either. The sun makes the earth swerve around it without any work being done. So the idea that dualism is wrong because of lack of conservation of energy is just a complete muddle.

It is also worth noting that both Descartes's and Leibniz's ideas of matter and spirit were quite different from ours. There is nothing in Descartes to indicate that spirit is 'non-physical'. It is just immaterial. Material meant something that acts mechanically because it excludes similar things from its space (is 'extended'). Light is not extended and light is part of physics so there is no particular reason why spirit should not be part of physics. In fact trying to tie arguments down to what people thought in the seventeenth century is hopeless. Descartes uses the word physics in two ways. One means 'practical engineering'. The other means everything that is, including God. Do we now have Cartesian dualism? The question is valueless. We have elements in physics that exclude other things from their space (aggregates of Fermions) and elements that do not (Bose modes like light). So maybe we do. But neither has 'free will' so maybe not. Physics is dualistic in all sorts of ways, but not dualistic in all sorts of other ways. To ask if dualism is false is to trivialise the topic.

These sorts of old chestnut philosophical puzzles based on ignorance of science need not concern us. What we want in philosophy of mind is to know what events in the brain correspond to phenomenal experience and the answer should be in rigorous physics.

Life exists only when free energy (food) is consumed, in a context of energy dissipation far from thermodynamic equilibrium and thus far from single causal path situations. So life do not have to deal with equilibration of energy but about its dissipation and so the choices are energically open.