Wednesday, July 18, 2012

Materialism of the Mind: List of Theories

Mental events as a "theory"
In most versions of materialism of the mind, mental events (events like fear, desire, belief, etc) are thought of as theoretical entities to explain human behavior. Materialists have three different answers of what those entities actually are.
  • Reductive physicalism says they are brain events
  • Non-reductive physicalism says they are programs that run on the brain
  • Eliminativism says that they do not exist
Reductive Physicalism
The General Idea
The general idea of reduction is that we once thought A entities and B entities were different, but now we realize that A entities are just a type of B entity. And so our language referring to A entities can be replaced with language referring to B entities.
There are two types of reductive physicalism of the mind:
  • Behaviorism: All mental events are are types of outward behavior; there is no inner mind.
  • Identity Theory: All mental events are just another name for physical brain events. So for example "the belief that P" is just another name for "P neurons firing". Note that if someone lacks P neurons (aliens? robots?) then they can't by definition "believe that P."
Non-Reductive Physicalism
The General Idea
The general idea of non-reductive physicalism is that us humans create our own groupings of physical properties, and label them as new "properties", even though they aren't really new properties outsides of our language and interests. We are the ones creating new groupings of properties, and labelling them as new properties even though they really aren't.
There are roughly three types of non-reductive physicalism of the mind:
  • Functionalism: The mainstream theory in philosophy of mind. The mind is a type of software or program that runs on the hardware of the brain. So a mental event could be realized by many different types of underlying hardware, including alien and robot brains. This is non-reductive because the language referring to the mental event could have a different underlying physical substrate in each case (human, robot, alien, etc).
  • Anomalous Monism: Like identity theory above, a mental event is just a brain event. However, unlike identity theory, the brain event might be different in every case. "Fear" might be constituted by activity in the amygdala in one case, and not in another. This is non-reductive because the physical reality of each mental event might be different in every case.
  • Supervenience: A picture on your monitor supervenes on the pixels: there cannot be a change in the picture without there being a change in the pixels. All materialist theories of mind (aside from behaviorism) are supervenience theories (since they say that the mind depends on the physical substrate), but supervenience can stand alone as it's own theory as well.
Elimininative Physicalism
The General Idea
The general idea of eliminativism is that we once had to postulate theoretical entites like phlogiston and luminiferous aether to explain some fact, but later we realized that such things do not exist.
  • Eliminative Physicalism: Mental events like fears, desires, and beliefs are like phlogiston: they were once useful in explaining some scientific fact, but science has shown that there are no such things. So, we need to ditch our talk of fears, desires, beliefs and so forth.