The philosophy of materialism holds that the only thing that can be truly proven to exist is matter, and is considered a form of physicalism. Fundamentally, all things are composed of material and all phenomena (including consciousness) are the result of material interactions; therefore, matter is the only substance.
Materialism - Wikipedia, the free encyclopedia
In philosophy of mind, dualism is a set of views about the relationship between mind and matter, which begins with the claim that mental phenomena are, in some respects, non-physical.
Dualism (philosophy of mind - Wikipedia, the free encyclopedia)
I'm a materialist. Believing in dualism (and often by extension - souls, spirits, God(s), New Age..) sounds nice, but I know the main arguments in favor of dualism, and none convince me so far or cause me to doubt materialism. The 'subjectivity of mental states' argument is I think the strongest argument for dualism.
I'd like to what you all think on the subject and where you stand.