How physicists handle the idea of Free Will?

How physicists handle the idea of Free Will?


Is this somehow supposed to be different or more significant than the questions:

How metallurgists handle the idea of Free Will?
How masseurs handle the idea of Free Will?
How miners handle the idea of Free Will?


If so, why should physicists be more concerned than the above? Why is free will more related to physics than to agriculture or irrigation?

That would be solipsism (only your mind exists). Solipsism is a form of idealism, but idealism doesnt have to be solipsism, it doesnt specifify how many minds or who they are.

Idealists think that is true yes, but physicalists think that physical things exist independently of minds.

So idealists say that the constructs of the mind are, somehow 'greater' than the physical processes that are, in fact, going on in the brain? That implies that they believe a part of us is outside the physical Universe. Apart from the fact that it could make one feel good to think that way, there is no evidence for this, is there?'.

Yeah, well, when I drop a hammer on my foot, the result isn't just 'mental'.

I think we have talked about supervenience before, but I dont remember the outcome. My impression of supervenience is that a supervenience relationship is always conceptual. So when someone says that your mind supervenes on your brain, it actually translates to "some other mind conceptualises that your mind supervenes on your brain". So a supervenience relationship doesnt describe any kind of physical activity and this means that supervenience isnt a physicalist view of the mind body problem.

Supervenience is a concept with broad applicability throughout philosophy that has particular importance to physicalism. …

Supervenience can be seen as the relationship between a higher level and lower level of existence where the higher level is dependent on the lower level. One level supervenes on another when there can only be a change at the higher level if there is also a change at the lower level. (e.g., a set of properties A supervenes upon a set of properties B when there cannot be an A difference without a B difference). …

Supervenience establishes such a relationship between the mental and the physical, that any change in the mental is caused by a change in the physical. Just as a shadow is dependent upon the position of the object causing it, is the mental dependent upon the physical. Physicalism thus implies (through modal realism) that:

No two worlds could be identical in every physical respect yet differ in some other respect.

The corresponding conclusion about the mental would be as follows:

No two beings, or things could be identical in every physical respect yet differ in some mental respect.

Hi pftest,

You jogged my memory... I remember talking about this now. I think what you're saying is that the supervenience relationship is conceptual in the sense that it depends on the individual who conceives of the relationship. Different individuals will have a different conceptual relationship so the supervenience relationship isn't consistent between individuals. Is that right?

Supervenience can be broken down into logical versus natural supervenience, but supervenience alone means the following:

Ref: http://en.wikipedia.org/wiki/Physicalism#Supervenience

For example, the pressure of a gas in a container supervenes on the temperature, number of molecules that make up the gas, and the volume of the container. The ideal gas law is used for illustration only; PV=nRT. So we can say the pressure supervenes on the physical state of the gas molecules. Without a change to the physical state of the gas molecules, we can’t get a change in the pressure. If we change one of the gas's properties, such as temperature, the pressure will also change. In this case, the pressure of the gas "naturally supervenes" on the physical state of the gas molecules. This relationship is given by the ideal gas law, PV=nRT. We might however, conceive of a world where the constant R is different and therefore, a mole of gas at a given temperature and in a given volume would have a pressure DIFFERENT than the pressure we know to exist. So the particular pressure of the gas we measure in our world “naturally supervenes” on the physical state according to our equation but it does not “logically supervene” since the value for R could conceivably be different in a different world.
(See Chalmers, “The Conscious Mind” pg 36)

For philosophy of mind, a physicalist would contend that the mind supervenes on the brain in some way. For the sake of illustration, we might consider a physicalist who would argue that the mind is a higher level phenomena created by the interaction of neurons in the brain. Therefore, the mind supervenes on both these interactions and on the neurons themselves. This is a supervenience relationship, and the physicalist would certainly argue this supervenicience relationship holds true.

Even if we accept however, that the mind naturally supervenes on the brain, we can't say it logically supervenes on the brain. Logical supervenience is a much more stringent requirement, and clearly p-zombies for example, are conceivable. Therefore, we don't generally suggest that the mind is logically supervenient on the brain. Natural supervenience is a subset of logical supervenience.

Just a quick example clarifying supervenience:

We have 2 different brains - B1 and B2.

If the mind is identical with the brain these will always produce different mentality (M1 != M2 where B1 = M1 and B2 = M2). // reductive physicalism

If the mind supervene on the brain these can sometimes produce identical mentality (M1 = M2 where B1 -> M1 and B2 -> M2). //non-reductive physicalism

So what do we know from introspection - our qualia changes over time, but we are still able to experience the same qualia sometimes. Let's say the brain state of 5 year old is B1 and this same person's brain state at 40 years is B2. Clearly these 35 years have changed massively the structure of his brain, but this person would be still able to experience and feel the same way as when he was at 5. This is a strong argument supporting supervenience and the multiple realizability. The mind-brain identity supporters can then say that we are mistaken and our memory is deceiving us, so we always experience different mental state, but with very tiny changes, which we can't "catch".

Nothing stops different brains from producing the same mind under supervenience, but it is not part of the definition.

Yes, you are right it's not, but its part of what non-reductive physicalism is.

[Mind-body supervenience] The mental supervenes on the physical in that any two things (objects, events, organisms, persons, etc.) exactly alike in all physical properties cannot differ in respect of mental properties. That is, physical indiscernibility entails psychological indiscernibility.

What you mean by "overall experience as a whole"? Take for example the feeling of surprise. How it feels to be surprised at 5 and at 40? Do you think its different?

We don't know if there are any mental states, which are the same for different individuals. We can only guess. That's why I gave the example with the same person at different ages. What I know from introspection is that the same chemicals can cause me different qualia, but I am also able to experience some things the same way, as when I was a kid. That's why the reductive physicalism has serious problems, because according to it, different brain state always produces different mental state.

And IIT is interesting, but we don't know if the mental reduces to information.

That's why the reductive physicalism has serious problems, because according to it, different brain state always produces different mental state.

Putnam’s argument can be paraphrased as follows: (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.

Type physicalism says that pain is C-fiber excitation. But that implies that unless an organism has C-fibers or a brain of an appropriate biological structure, it cannot have pain. But aren't there pain-capable organisms, like reptiles and mollusks, with brains very different from the human
brain? Perhaps in these species the neurons that work as nociceptive neurons--pain-sensitive neurons--aren't like human C-fibers at all. Can the type physicalist reply that it should be possible to come up with a more abstract and general physiological description of a brain state common to all organisms, across all species, that are in pain state? This is highly unlikely, but how about inorganic systems? Could there not be intelligent extraterrestrial creatures with a complex and rich mental life, one that is very much like ours, but whose biology is not carbon-based? And isn't it conceivable--in fact, at least nomologically if not practically possible--to build intelligent electromechanical systems (that is, robots) to which we would be willing to attribute various mental states? Moreover, the neural substrates of certain mental functions can differ from person to person and may change over time even in a single individual through maturation, learning, and injuries to the brain. We should keep in mind that if pain is identical with physical state C, then pain is identical with state C not only in actual organisms and systems but in all possible organisms and systems.

These considerations are usually taken to show that any given mental state is "multiply realizable" in a large variety of physical/biological structures, with the consequence that it is not possible to identify a mental state with a physical state. If pain is identical with a physical state, it must be identical with some particular physical state; but there are indefinitely many physical states that can "realize" (or "instantiate," "implement," etc.) pain in all sorts of pain-capable organisms and systems. So pain, as a type of mental state, cannot be a neural-state type or any other physical-state type.

This, in brief, is the influential "multiple realization" argument against type physicalism Hilary Putnam advanced in the late 1960s (we will recur to multiple realization in the next chapter). It had a critical impact on the way philosophy of mind has developed since then: It effectively retired type physicalism as the reigning doctrine on the mind-body problem, throwing the very term "reductionism" into disrepute and ushering in the era of "nonreductive physicalism." Further, it inspired a new conception of mentality, "functionalism," which has been highly influential since the 1970s and which is arguably still the most widely accepted view on the nature of mind.

When talking about the mind<>body relationship, i think the first thing a physicalist position needs, is a matching example of a physical<>physical relationship. Is the mind<>brain relationship the same as the water<>riverbed relationship? A rock<>its molecules?

If a physicalist cannot find any relationship in the physical world that matches their ideas of the mind<>body relationship, then by definition it is not a physical relationship and it cannot have arisen in a physical manner.