Phineas Gage is not a good argument for materialism!! You can totally have a dualism where each particle has a "material" and a "mental" component. When you put all the particles together, you get the physical brain on the material level, and the emergent structure of consciousness on the mental level. "Every particle is just a little bit conscious" is such an elegant answer to the hard problem of consciousness. Also it means the electrical wiring in your house is probably conscious!!

You could have that setup. 

Leaving aside any question of whether it explains anything, or any question of what it means to be “a little bit conscious” – the reason I said “in a practical human sense” is that this theory offers basically nothing to any of the actual existing people who want non-materialism.  If you need physical particles to combine in order to get consciousness, you don’t have souls, you don’t have an afterlife, you don’t have astral projection or spirit-journeys or anything like that.