Proportionality and omissions

Abstract

In response to the exclusion argument against mental causation, Yablo ( 1992, 1997) proposes a proportionality constraint on what can count as a cause: where distinct, simultaneous putative causes involve properties that stand in the determinable/determinate relation, only the property that is proportional to the effect counts as the cause. The having of property C is proportional to effect E if and only if (i) for any determinable C* of C, had C* obtained without C, E would not have obtained, and (ii) for any determinate C′ of C, had C obtained without C′, E would still have obtained. In Yablo’s terminology, where (i) holds we say C* does not screen off C from E, and where (ii) holds we say C screens off C′ from E. So C is proportional to E iff none of its determinables screen it off, and it screens off all its determinates (Yablo 1997: 267). Proportionality is itself an exclusion principle: only one in a set of properties related by the determinate/determinable relation can be proportional to a specific effect.Sophie, the pigeon, is trained to peck at red objects. When presented with a scarlet object, she pecks. Scarlet is a determinate of red, while red is a determinate of coloured. Being presented with a scarlet object does not cause the pecking, since had she been presented with a red object that is not scarlet she would still have pecked; whereas being presented with a red object does cause the pecking, since had she been presented with a coloured object that is not red she would not have pecked. Being coloured doesn’t screen off being red from pecking, but being red screens off being scarlet. Similarly, had some mental property M obtained without its corresponding determinate brain …