Full Idea
Its inability to explain the possibility of "mental causation" doomed Cartesian dualism.
Clarification
'Mental causation' is when physical events are affected by conscious thought
Gist of Idea
Cartesian dualism fails because it can't explain mental causation
Source
Jaegwon Kim (Philosophy of Mind [1996], p. 4)
Book Reference
Kim,Jaegwon: 'Philosophy of Mind' [Westview 1998], p.4
A Reaction
This is a modern way of stating the interaction problem. Personally I am inclined to think that dualism was doomed by the spread of the scientific materialist view to every other corner of our knowledge except the mind. Plenty of causes baffle us.