The theory I have presented of substance concepts and the thoughts governed by them is similar in a number of respects to Evans' theory of “information based thoughts” in The Varieties of Reference (1982). Evans' information based thoughts were thoughts containing information derived from perception or testimony, where the thinker also had “an adequate concept” of the information's source. Evans is not altogether clear, however, on what “information” is supposed to be. Initially (p. 122n), he refers us to J. J. Gibson (1968), but his subsequent discussion, which makes reference to informational states that “fail to fit” their own objects, “decaying” information (p. 128n), “garbled” information (p. 129), informational states that are “of nothing” (p. 128) and so forth, is glaringly inconsistent with Gibson's conception of information.

The clearest images Evans presents us are information contained, on the one hand, in a photograph, and on the other, it seems, in a percept (not, as Gibson would have had it, in energy impinging on sensory surfaces). But “[a]n informational state may be of nothing: this will be the case if there was no object which served as input to the information system when the information was produced” (p. 128). On the other hand, “two informational states embody the same information provided they result from the same informational event … even if they do not have the same content: the one may represent the same information as the other, but garbled in various ways” (pp. 128–9).