For my next philosophical problem I present here the general theme of my philosophy of mind term paper. I have decided to present this short version as well as a long version (the long version is still half the length of my term paper). I have listed references at the end of the long version. If you would like to challenge anything I say, please read the long version first. I welcome questions on either.
My paper dealt with a principle known as "the causal closure of the physical" (hereafter “CC”). CC says that all physical effects have physical sufficient causes. A less technical way to say this is that physical causes fully explain physical effects, such that nothing physical requires a non-physical explanation. In philosophy of mind this principle is used to argue that mental causes are actually physical, which is a step toward saying that the mind is nothing more than the brain. More broadly, the principle of causal closure relates to the question of whether physics can ultimately explain everything. I accept causal closure, but I do not think the mind is just the brain or that physics can explain everything. Here’s why.
CC enjoys wide support among contemporary philosophers, and I think it is easy to see why. It has intuitive plausibility, that is, it sounds like something that should be true. We expect, for example, that if a candle moves, then there must be some physical force that makes it move. It would be unscientific, perhaps even superstitious, to think otherwise.
Nevertheless, many people believe that there are non-physical causes that affect the physical world. I find this claim to be intuitively plausible as well. It need not have anything to do with superstitious causes such as a ghost moving the candle. Consider, instead, the chairs around my dining room table. They are undoubtedly physical objects in a physical arrangement. However, they would never have been shaped as chairs and arranged as they are were they not produced to be purchased, with a view toward civility and hospitality. Here we have economic and ethical causes of what seem to be physical effects.
So we have a dilemma: both CC and not-CC are plausible. The way to resolve this is to try to justify each side in a stronger way. When we do this, however, the conflict disappears. It turns out that CC can be true even though non-physical causes are necessary to explain my chairs.
The best justification I know for CC is in terms of the conservation laws of modern physics, such as the conservation of mass/energy and conservation of momentum. Let us define physical causation as the exchange of conserved quantities, and a physical effect as a variation in conserved quantities in a thing (e.g. if the cause is my hand transferring its momentum to a candle, then the effect is the candle’s change in momentum). Then, according to whatever conservation law may come into play, physical causes must involve a reciprocal variation in conserved quantities (my hand loses the momentum that it transfers). This necessary reciprocal variation is a physical sufficient cause for the physical effect—and so we have a strong basis for CC.
Notice, now, that we have clarified physical effects as changes in conserved quantities. This means that concrete things like my table and chairs are not, strictly speaking, physical effects. While we may refer to my chairs as physical things in everyday language, we have to recognize that as chairs they are not the kind of physical effects to which CC applies. CC applies only to properties of the chairs like their mass.
This has an important consequence: there is no obvious reason why things with physical properties may not also have other properties, and obey other laws. My chairs clearly obey the law of conservation of energy, but they might also obey the law of supply and demand at the same time.
We now need to look at the other side of our dilemma. Could other kinds of properties and laws be necessary to explain my chairs—that is, in a way that cannot be reduced to the physics of conserved quantities?
The answer is “yes.” Dynamical systems theory explains how a complex pattern of activity (a “dynamical system”) can direct its components in such a way the pattern is necessary for its results in a way that no individual components is.
The key to understanding dynamical systems is that every cause requires certain background conditions to produce an effect. (An example is that in order for flipping a switch to turn on my light, my home must be properly wired.) What makes a system “dynamic” is that the structure or pattern of the system can maintain and direct itself with a range of possible components. It does this by arranging background conditions based on the available components. A simple example is that whether I eat fat or sugar, my body will convert it to the same form of energy chemical energy (ATP). Living things are the outstanding examples of dynamical systems: they keep a constant internal state and reproduce themselves while the molecules making them up constantly change.
The ability of dynamical systems to produce their effects with a range of possible components by altering background conditions means that the system is necessary for its effects over a broader range of background conditions than any particular component is. The components of a dynamical system retain their own nature, but they become captive to the “higher-level” pattern of the system. This means that the properties of the system are necessary to explain its effects in a way that cannot be reduced to the physics of the components. We have, then, the answer to our question.
Returning to the dilemma, we can see that although CC is justified, it does not mean that physics can explain everything. Physics explains the physical aspect of all things, but there is just more to reality than that. My chairs simultaneously obey CC, the law of supply and demand, and standards of hospitality. While it is true that there would be no economy if there were no objects with physical properties, it is also true that the economy determines what happens with “physical” objects like my chairs in a way that physics does not.
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