Why is a grapefruit known as such, given how dissimilar it is to a grape? More importantly, why is the question framed so? It is only a small perturbation that ripples through the query’s character if the edible nouns swap places, yet the question as written is more likely to be asked than its variant.

Two mechanisms are at play in the determination of the order of the nouns being compared. Given the numerous acrobatic varieties of sentence construction, it is more precise to say that two mechanisms are at play in the determination of which noun should be interrogated. Though it’s unusual to see such a term used in this context, the meaning is clear: with respect to the question initially posed, no one would have trouble agreeing that ‘grapefruit’ is being roughed up in the interrogation room while ‘grape’ goes about its daily life ripening on a vine.

The first mechanism concerns the relative prominence of the nouns in the public consciousness. The noun of lesser prominence is the interrogatee. This follows from human nature. We are skeptical of, and more apt to question, something with which we are less familiar. The second mechanism concerns how the nouns relate to each other etymologically. The family of comparison questions this post addresses are those in which the nouns being compared share a word, and for such questions the noun of greater etymological complexity is the interrogatee. The rationale for this is plain: if one of the nouns must be interrogated and the other not, and the determination is to be made through the lens of etymological complexity, then the noun left unquestioned must be the etymologically simpler of the two, because if, in contrast, the simpler is questioned, anything incorporating it as part of a more complex construction must also be, so as to address the perception of guilt by association. The reasonable assumption here is that the existence of root words and other basic building blocks precedes the more complex arrangements of which they are a part.

In the example question given, it’s clear that both mechanisms are aligned. In the public consciousness, a grapefruit is less prominent than a grape, and it is also a compound word incorporating the noun with which it’s being compared. The alignment of both mechanisms is responsible for the greater probability of the question being asked as it is rather than with the edible nouns swapped.

One is naturally prompted to wonder at an example where the two mechanisms are in opposition. Such a case is given by keyboard versus board, where the former refers collectively to its music and type varieties. Keyboard is a compound word involving the noun with which it’s being compared, yet is more prominent than board in the public consciousness, thus one mechanism proposes to interrogate ‘keyboard’ while the other proposes to interrogate ‘board’. The result is ambivalence regarding the noun to be interrogated in a comparison question.