  The general principle behind this second claim is ‘same proximate cause, same immediate effect’. It is likely that the disjunctivist will simply reject this principle. The disjunctivist may insist that in a case of genuine perception, even if the objects of perception are distal causes of the subject’s experience, they are also figure non-causally as essential constituents of it. So the occurrence of the relevant brain processes won’t be sufficient to produce the kind of mental event involved in perception, unless further non-causal conditions necessary for the occurrence of that kind of mental effect also obtain. At this point, the disjunctivist and her opponent may simply disagree as to whether there are any psychological effects that have significant non-causal constitutive conditions attached. And this connects with familiar debates as to the tenability of externalist views in the philosophy of mind. (For further discussion of the causal argument see Langsam 1997, Snowdon 2005b, and Martin 2004).