Ullin Place - Place's Identity Theory Vs. That of Feigl and Smart

Place's Identity Theory Vs. That of Feigl and Smart

There are actually subtle but interesting differences between the three most widely credited formulations of the type-identity thesis, those of Place, Feigl and Smart which were published in several articles in the late 1950s. Place's notion of the identity involved in the identity thesis is derived from Bertrand Russell's distinction among several types of is statements: the is of identity, the is of equality and the is of predication. Place's version of the relation of identity in the so-called identity thesis is more accurately described as an asymmetric relation of composition. For Place, higher-level mental events are composed out of lower-level physical events and will eventually be analytically reduced to these. So, to the objection that "sensations" do not mean the same thing as "mental processes", Place could simply reply with the example that "lightning" does not mean the same thing as "electrical discharge" since we determine that something is lightning by looking and seeing it, whereas we determine that something is an electrical discharge through experimentation and testing. Nevertheless, "lightning is an electrical discharge" is true since the one is composed of the other. Similarly, "clouds are water vapor" means that "clouds are composed of droplets of water vapor" but not vice-versa.

For Feigl and Smart, on the other hand, the identity was to be interpreted as the identity between the referents of two descriptions (senses) which referred to the same thing, as in "the morning star" and "the evening star" both referring to Venus. So to the objection about the lack of equality of meaning between "sensation" and "brain process", their response was to invoke this Fregean distinction: "sensations" and "brain" processes do indeed mean different things but they refer to the same physical phenomenon. Moreover, "sensations are brain processes" is a contingent, not a necessary, identity.