Abstract: There is a parallel between a project pursued by the logical positivists and the contemporary effort to determine whether intentional properties can be naturalized. According to the verificationist account of meaningfulness advocated by the positivists, a sentence is meaningful (or “cognitively meaningful”), if and only if, it stands in an appropriate relation to observation sentences. Sentences that are not appropriately related to observation sentences are shunned as nonsense. Similarly, those concerned to naturalize the intentional hold that intentional properties are real, if and only if, they stand in an appropriate relationship to physical properties. The verificationist account of meaning suffered the death of a thousand failures. No one could produce a relation that did not include too much or exclude too much. I maintain that attempts to produce a relation that will do the work naturalists require, may well meet the same fate. On the pluralistic account of science that I favor, scientifically legitimate properties stand in many different relations to physical properties, and as science progresses, new properties are discovered that stand in new relations to physical properties.

Keywords: logical positivism, meaningfulness, naturalism, pluralism, properties, verificationism,