H. P. Grice and J. M. Keynes: the generator property

"Since the number of GENERATOR PROPERTIES is finite, the number of groups also is finite."

"If a set of apparent properties arise (say) out of three GENERATOR PROPERTIES φ1φ2φ3, this set of properties may he said to specify the group φ1φ2φ3."

"Since the total number of apparent properties is assumed to be greater than that of the generator properties, and since the number of groups is finite, it follows that, if two sets of apparent properties are taken, there is, in the absence of evidence to the contrary, a finite probability that the second set will belong to the group specified by the first set."

"There is, however, the possibility of a plurality of generators."

"The first set of apparent properties may specify more than one group,—there is more than one group of generators, that is to say, which are competent to produce it; and some only of these groups may contain the second set of properties."

"Let us, for the moment, rule out this possibility."