Mind/body dualism is the root of all philosophical confusion. Hart has the classical version of this disease; computation was supposed to gloriously overcome it but kind of got lost along the way. I don't have any great tricks for seeing past it, except to note if you overemphasize one to the neglect of the other, you are probably doing something wrong. Eliminative materialists and radical idealists are equally wrong in this way. See also dumbbell theory or the section on teleology in Weird Studies/Tarot/Wheel of Fortune.
That is, mind/body dualism and related philosophical confusions, not duality as such (for that, see nondualism ). This is a founding myth of Western thought and possibly all thought, but it's wrong wrong. Very hard to see past it. Computation and cybernetics were supposed to get us beyond dualism but for the most part just replicated the mind/body distinction in software/hardware.
These both explain, in quite different ways, why dualism might be a cognitive universal.