ABSTRACT
WE are now in a position to review the massive sets of data discussed in the preceding sections, and to draw some more general conclusions. Comments have already been made in connection with certain issues as they arose, but a more concentrated discussion has been postponed until all the data had been presented. This discussion can most profitably start with a consideration of a relatively old but still very live problem, viz. that of the primacy of first-order as opposed to higher-order factors. This problem is often linked with the names of the main protagonists of the two positions: Spearman, who advocated the primacy of higher-order factors (or ‘g’ factors, as they used to be called), and Thurstone, who advocated the primacy of first-order factors (or group factors, as they are called in England). It is often (erroneously) implied in textbooks that the opposition is absolute, and can be decided on the basis of some crucial experiment; it is also often argued, or assumed, that such an experiment was in fact performed by Thurstone, and that the Spearman position was thereby made untenable. None of this is true.
