During the last year, I have read more than 400 cover letters (I have lost track) in the context of four (junior) job searches. These jobs were all advertised in political science, but three of the positions also encouraged applications by philosophers and other social scientists. (Two of these searches are still ongoing, so I will write rather abstractly and will make gross generalizations that, of course, do not apply to all the candidates.) And what follows is a minor reflection on the nature of the cover letter.
Now, in some academic environments cover letters matter very little (compared to, say, CVs, research or teaching statements, the writing-sample, or letters of recommendation)--as a PhD student in the 1990s, I was told stories about applications with just a single sentence cover letter working just fine. So, what follows is largely irrelevant to such environments (as I suspect is the case in top research departments Stateside). However, in a Dutch academic context cover letters matter a lot. This is not just because in my department we ignore letters of recommendation entirely in order to winnow down the candidate-pool to a shortlist. (I like that because it really does reduce prestige bias, but about that some other time more.) For, given the grant environment, which rewards publication at a regular clip in above average journals (for a more cynical take recall this post), one might have thought we focus exclusively on CVs. Yet, despite the importance of perceived grant-making potential, committee members really read cover-letters carefully, and this turns out to be quite normal in the Dutch civil service (and in Europe universities take on, for good and evil, the characteristics of their local civil service) and even business.
I said above I was going to offer a minor reflection, by which I mean that I am not going to list all the features of a would-be-successful cover letter. Most of such features involve reflection on how one can present oneself (skills, research-trajectory, teaching experience/attitude, grant-building, etc.) in light of the nature of the position, the needs of the hosting department, and wider fit with the research unit/department/institution/environment. A lot of that actually requires some local knowledge and, with the benefit of hindsight, I am surprised by how few queries one receives about the nature of the position and other relevant characteristics. (The previous sentence is not meant to be critical of would-be-candidates; I know that for a lot of candidates, who are applying to many positions with low odds of success, time is a luxury they do not possess.)
Okay, so much for set-up.
What I have learned from reading 400 cover letters is how at the start of their careers (most of the applicants fit this category), few people are capable of characterizing their own research to professional peers. (The previous sentence is compatible with the thought that these letters are not an unbiased sample.) By this I mean that almost nobody conveys what is distinctive about their research. By 'distinctive' I mean, what's the key insight, trick, or contribution one is using (e.g., applying and refining the PSR to problems of inter-generational justice) or central research program (e.g., using formal features of Scotus's philosophy of mind to develop new accounts of political representation).
The examples of the previous paragraph are obviously fake. And they may be thought to exemplify facile superficiality. But notice (a) that you don't need to limit yourself to a single sentence; one can easily use a paragraph or two to characterize one's research if it conveys distinctive quality of one's would-be-contribution. In addition, (b) there is a world of difference between superficiality and succinctness (e.g., any good Haiku). And if one is worried about overselling, one can always qualify one's' distinctive contribution in various ways.
Now, one may think that a research statement is the proper site of conveying the distinctness of one's research agenda/project or contribution. Fair enough. But (i) not all application processes demand a separate research statement. And (ii) what I have said about cover letters is also true of a research statement. I can't tell you how many of the presentations of people's research are nearly indistinguishable from each other, stringing together key buzz words about a field (even characterizing the field in homogeneous ways) without saying anything about what's so special about their contribution. (The situation gets worse when one reads quite a few applications from the same department--the visible hand of local gurus shaping the young is still strong.) This is not just due to the way in which fashion/trends percolate their way through a generation of the young's research (are all the kids till studying the grounding relation in metaphysics or have they moved on?)
Now, I am not saying it's easy to characterize one's own research. Sometimes finding one's voice only happens after one has landed a job (or two) [recall]. That is one requires a certain distance from one's own research. For example, it's only a few years ago that I recognized that one of my main moves as an early modern scholar was to take the dominant narrative for any X [e.g., Berkeley, Hume, Spinoza, Adam Smith] as a fellow-traveler of the scientific revolution or scientific naturalism and turn X into a (friendly, clever, severe, etc.) critic of the scientific revolution, mathematical physics (etc.). And one of my tricks as a philosopher of economics (which dawned upon me, in fact, during my blogging) is to take a very complicated mathematical concept in contemporary economics, and study it at its introduction in the economics profession in order to reveal the modal, methodological, or evidential moves that underpin it (or not).
Presenting oneself as essentially one move feels a bit naked; it's not obvious whether others will grasp the relevance of or be excited about one's trick/project, etc. They may well think it sounds easy or trivial. And, of course, one can be a whole lot more (a dedicated teacher, a workplace activist, an innovative public disseminator, a warm colleague, etc.) than that key move. (Perhaps, one even has more than one move; swell!) By all means don't be shy about all of that important stuff in a cover letter.
To be sure, not everybody is looking for a distinctive researcher and not everybody would think that sounding distinctive is a good, first proxy to research excellence in a grant-heavy-research-environment (recall we're just talking about the marginal difference between having a shot at a short list or rejection all other things being equal, but, of course, lots of things are not equal). I am not in the how-to-turn-one's-portfolio-into-job-placement-success business. By no means ignore your local job-placement officer--she really cares about how you do on the academic job-market, while I probably don't. Moreover, most of the people whose cover letters are not distinctive do get jobs, so I do not want to over-emphasize the point. But, having said all of that, a cover letter is a chance to convey what's exciting about a candidate's research profile. If your professional future depends on it, why not call attention to what's really special about your research?