Philosophical materialists maintain that the brain is all that's involved in our cognitive experience and that there's no need to posit the existence of an immaterial mind or soul. Moreover, given that brain function is the product of the laws of physics and chemistry, materialists argue that there's no reason to believe that we have free will.
For materialists mind is simply a word we use to describe the function of the brain, much like we use the word digestion to refer to the function of the stomach, but, they argue, just as digestion is an activity and not an organ or distinct entity in itself, likewise the mind is an activity of the brain and not a separate entity in itself.
As neurosurgeon Michael Egnor discusses in this fifteen minute video, however, the materialist view is not shared by all neuroscientists and some of the foremost practitioners in the field have profound difficulties with it.
Egnor explains how the findings of three prominent twentieth century brain scientists point to the existence of something beyond the material brain that's involved in human thought and which also point to the reality of free will.
His lecture is an excellent summary of the case for philosophical dualism and is well worth the fifteen minutes it takes to watch it: