Between these two extremes there are several intermediate forms, wherein the use of one rather than another will depend upon the taste of the writer. The question, however, is a question of euphony, rather than of aught else. It is also illustrated by the principle of not multiplying secondary elements. In such a word as fruit-full-er, there are two additions to the root. The same is the case with the superlative, fruit-full-est.
[§ 434]. In the Chapter on the Comparative Degree is indicated a refinement upon the current notions as to the power of the comparative degree, and reasons are given for believing that the fundamental notion expressed by the comparative inflexion is the idea of comparison or contrast between two objects.
In this case, it is better in speaking of only two objects to use the comparative degree rather than the superlative—even when we use the definite article the. Thus—
This is the better of the two
is preferable to
This is the best of the two.
This principle is capable of an application more extensive than our habits of speaking and writing will verify. Thus to go to other parts of speech, we should logically say—
Whether of the two,
rather than