The Mind: Five Kinds of Physicalism

Another 20th century response to the question of mind (not to mention Cartesian Dualism) was Physicalism. Unfortunately, Physicalism, like ice cream, comes in more than one flavor. Before we delve to deeply into the varieties of physicalism, a broad explanation is in order.
Physicalism, which was called Materialism in some early incarnations, asserts that the mind is part of the physical universe and subject to the physical laws that govern the universe. They tend to identify the mind with the brain as the physical embodiment of it. By placing the mind physically into the body by way of the brain, the interaction problem disappears. No more is there any question about just how messages move to and from the body and the mind.
Now, with the broad strokes out of the way, it's time to move on to the specific incarnations of physicalism.
Type Physicalism adheres to the idea that particular brain states could be successfully identified with particular mental states. In other words, the sensation of pain would be able to be identified with some particular state in the brain, or the state of pleasure at eating well made meal would be able to be identified with a brain state.
Of course, this seemingly simple solution becomes problematic very quickly. The most prevalent problem is the fact that there are a great many different types of brains. It would be difficult to be able to establish with any certainty the equivalence of brain states in different kinds of brains. The less prevalent problem rests with the possibility that different brains inside of a species, for example, may have subtle differences that preclude being able to draw the equivalence.
Token Physicalism shares some basic ideas with Type Physicalism. It holds that mental states are identifiable with physical states. However, it does not presume that the mental state and the physical state be identifiable with one another, merely that a mental state is identifiable with a physical state.
This position is problematic, as well. The big problem here is how to establish that physical states represent mental states if there is no direct physical correlation between them.
Eliminative Physicalism holds that mental states as such are a fiction. As such, there is no need to try to tie them to a physical state. Under Eliminative Physicalism, there are no mental states of belief, pleasure, or desire, to name a few. They argue that such mental states are merely holdovers from outdated psychological theorizing and have no place in a theory of mind.
The problem faces here is how to explain the apparent existence of exactly these kind of motivating mental states.
Reductive Physicalism holds that theories of mental states, as such, can be explained in terms of physical theories about the brain. Where this breaks from Eliminative Physicalism is that there is no denial of the mental states in question. It simply denies the need to address them at all. It is primarily concerned with brain states.
Non-Reductive Physicalism asserts that attempts to reduce mental states to simple brain states is a failed endeavor. The principle argument they make is that simple brain state theories cannot account for complex mental states. Another way to look at it is to think about the difference between using building blocks as a child and designing a skyrise. You can build something that stands with building blocks. However, the simple principles you employ to build with such toys cannot account for the vast array of variables and generalizations required to understand the forces at work in building a skyrise.
Both Reductive and Non-Reductive Physicalism suffer from the same problem. Neither one can provide any solid evidence to defend their positions.