The Mind-Body Problem: Physicalism
Physicalism ◮ According to physicalism, everything that makes you up is physical, material, spatial, and subject to laws of physics. ◮ Because of that, we need not worry about causal explanations outside of physics affecting things in the physical world − there are no such causes. ◮ Nonetheless, physicalists still want to be able to make sense of the psychological descriptions of our mental life (beliefs, desires, thoughts, etc.) and they divide on how exactly to understand these things.
Identity ◮ According to the mind-brain identity theory, each mental fact is identical to a pariticular brain fact. E.g.: ◮ The sensation of pain is identical to a certain physical process in the somatosensory cortex. ◮ The experience of an orange after-image is identical to a certain physical process in visual cortex. ◮ Etc. ◮ The primary argument for mind-brain idenity seems to be an inference to the best explanation
Inference to the best explanation ◮ While not without points of debate, there is a general method of certain good arguments that we can describe as “inference to the best explanation” ◮ Given a particular phenomenon, there are always multiple ways to explain it, and we seem to be able to often select one of those as the best ◮ Suppose we hear and see jets fly over in formation, and we are comparing the following possible explanations: (A) They are practicing for a flyover for the game on Saturday. (B) War has broken out between the U.S. and Canada and they are flying a military mission. (C) Four eccentric billionaires have all bought fighter jets and happen to be flying in the same area at the same time. (D) It is a hoax where the stadium is merely blasting fighter-jet sounds and seeing if people will believe that jets flew over ◮ Most people will believe (A), and will believe that they are justified in believing (A) because it is an objectively better explanation than the other options (though of course this list is only some of the other options)
Inference to the best explanation ◮ Suppose we hear and see jets fly over in formation, and we are comparing the following possible explanations: (A) They are practicing for a flyover for the game on Saturday. (B) War has broken out between the U.S. and Canada and they are flying a military mission. (C) Four eccentric billionaires have all bought fighter jets and happen to be flying in the same area at the same time. (D) It is a hoax where the stadium is merely blasting fighter-jet sounds and seeing if people will believe that jets flew over ◮ (A) is better than (D) because (D) could at most explain the sound, whereas (A) explains the fact that we see and hear the jets ◮ (A) is better than (C) because it is far simpler ◮ (A) is better than (B) because it has a higher initial probability ◮ There are other theoretical considerations, and philosophers debate what exactly makes an explanation best, but we seem to have enough of a grasp on the type of argument to be able to make such inferences.
Identity ◮ The facts that the identity theorist claims need to be explained are the systematic correlations between things that go on in the mind and things that go on in the brain. ◮ While the dualist may be able to explain these facts somehow, it seems a far simpler explanation of the systematic correlations to simply say that they are two ways of talking about the same facts. ◮ We can summarize the argument thus: 1. There is a systematic correlation between mental properties (like “is seeing snow”, “is feeling pain” or “is solving a math problem” etc.) and brain properties (like “is a firing of C-fibers”, “is occurring in the right temporal lobe”). 2. The best explanation of this correlation is that mental properties are brain properties (in the same way “is water” can be thought to express the same property as “is H 2 O”). 3. Therefore, it is most reasonable to believe that mental properties are brain properties.
The Problem for Identity ◮ The main problem for mind-brain identity is what is called multiple realizability . ◮ In particular, the identity theorist says that pain and perception are certain physical-chemical properties, but this would imply that things which had different physical-chemical properties did not feel pain and did not perceive things. ◮ But, we have strong reason to think that animals whose brains are highly unlike ours, such as an octopus, can still feel pain, feel hunger, and generally share mental properties with humans. ◮ Likewise, we have no reason to think that martians or cyborgs could not feel pain and hear sounds even if their brains did not share physical properties with our brain.
Functionalism ◮ Functionalism is the view that mental properties are identical to certain input-output relations (i.e. functional properties ) ◮ It follows quite naturally from the failure of identity theory; whether or not something is thinking is not based on its having a certain physical property. Instead, it is based on what the thing is doing . ◮ For instance, pain seems to be a certain response to damage that creates an impulse for aversive behavior. ◮ Humans feel pain, but they need not always do it in the same brain region, and octopi can feel pain in highly different ways. ◮ What unites human pain and octopus pain is not the physical properties, but the role that each plays within the organism
Functionalism ◮ Machines helpfully illustrate functionalism ◮ Something is a mousetrap if and only if it takes in living mice and gives out dead mice ◮ Something is Microsoft Word if it takes certain inputs (keyboard strokes, and mouse clicks) and outputs a certain document. ◮ While each instance of Microsoft Word is on a particular bit of hardware it is not identical to that hardware and could exist on quite different hardware (e.g. computers can be built with vaccuum tubes or with microchips). ◮ Similarly, functionalists say that pain could be realized by carbon, silicon, or other materials, and could be realized in lots of different ways; it is merely defined by its input and output. ◮ Mental states are defined in terms of their causal relations to perceptual inputs, behavioral outputs, and other mental states.
Functionalism ◮ Mental states are often highly complex ◮ For instance, a “desire for chocolate” state is not just a state that outputs chocolate-eating behavior when it receives chocolate visual images ◮ Instead, a desire for chocolate might interact with your belief that there is chocolate in your dorm room and output walking there; it might take as input the sight of chocolate and output and intention to eat chocolate, but your desire to lose weight might take that intention as input and output a non-chocolate eating behavior. ◮ While obviously complex, we do seem to be able to make sense of this network of connections and dispositions to act in certain ways as an account of human mental life.
An Objection to Functionalism ◮ According to functionalism, mental properties are functional properties of objects − they are had entirely in virtue of how the thing responds to certain inputs. ◮ However, there seems to be reasons to think that something could have all the same inputs and outputs as a machine without there being any conscious mental life. ◮ Specifically, consider the Chinese Room thought experiment
An Objection to Functionalism It thus seems that 1. Anything that a computer could do (i.e. any function) could be done by a person following certain rules with symbols they don’t understand 2. No thinking or feeling would be had by the person in virtue of what function they were fulfilling 3. The room or complex of rooms in which they were fulfilling the function would not have conscious awareness 4. Thus, each function could exist without there being any conscious awareness 5. Therefore, conscious occurrences like pain, perception, and thinking cannot be identical to certain functions.
Recommend
More recommend
