The conceptual interaction problem (issue facing interactionist dualism)
P1: It is inconceivable for two things to causally interact, unless their surfaces come into contact with each other.
P2: According to substance dualism the mind is unextended and has no surface.
C1: Therefore it is inconceivable for the mind to interact with the body.
P3: What is inconceivable is impossible.
C2: So mind-body interaction is impossible.