Role Play

One of the most difficult things about the English language is the use of prepositions like for, of, with and others. Most grammar books will list ten different ones, but all propositions are about relationships. These can be between nouns, pronouns, or phrases in a sentence. Moreover, some nouns have only one or sometimes several prepositions that can be used with them. One of those is the word role. In scientific manuscripts it is a common word, but too often it is followed by the wrong preposition for the situation. Role can take one of three prepositions – in, for, or of —depending upon the context and the relationship being discussed. To demonstrate the proper contextual preposition for role, let’s set-up the following scenario.

You are researching biological pathway X with multiple components, some of which are known and some of which are not. Some of these components are part of the direct steps in the pathway and some indirectly influence the pathway in some capacity. You have just identified Molecule A as a direct component. To describe its role, you would use the preposition in: We have discovered a role in X for A. What if you had known about A being essential for X, but not how and now you have some insight into this issue, then you might say: One possible role for A in X is to create a feedback loop. At this point you might notice that both in and for are used, albeit in a different order. Prepositions define relationships, and the word role is also about relationships. A role is both in and for, and both components need to be clearly indicated in the text. Just as one might talk about the roles in a theatrical production or the roles of the actors in that production, both components must be understood by the reader.

Of is most often used in place of possessives: The role of Molecule A is rate-limiting or Molecule A’s role is rate-limiting. Using the previous made-up sentences, you could substitute of for for in the second without mush loss of meaning (One possible role of A…), since that is sort of a possessive, but it cannot be substituted in the first. However, the substitution would not sound right to most native speakers, since it is not really a possessive. It is this kind of substitution that often happens with non-native writers.

Sorting out when to use in is straight forward, when you think about it.In the scenario above it links A to X.Choosing between of and for is a little more difficult, and while they are almost interchangeable, they are not, really.Of should generally be used for the role of something that is already known or settled and where the possessive would be awkward.It tends to be a word with less presence or emphasis, sort of pedestrian or blah.For, on the other hand, is more emphatic and direct.It makes an assignment in the relationship, usually one that may not have been there beforehand.On the practical level, if it is clearly not a possessive and you are not sure which to use, choose for.