I am writing a paper in mathematics.

Stone theorems have a long history. B [B78] proved the stone theorem for the B model. C and D [CD14] not only prove a stone theorem for the cake process in random environment, but also have a nice overview of existing results.

(here B, C and D are some names, and 'stone theorem' and 'the cake process' also represent something else, but it is not important for the structure)

Question: is it ok to use a past tense in the first sentence which refers to 1978, but use a present tense in the second sentence which describes something that happened relatively recently, in 2014?

  • Even though 2014 is 'relatively recent', it's still in the past right?
    – Varun Nair
    May 23, 2016 at 11:51
  • @VarunKN It is the past indeed, but I had the impression that sometimes in papers people write in the present tense about another paper even though it is clearly in the past. Could something like the historic present be used in this context?
    – Sinusx
    May 23, 2016 at 12:03

2 Answers 2


It's perfectly fine to use the present tense for all research, even going back to ancient times; see here for another question about this.

However, there is a way that you can usefully shift tense in a literature review in a scientific paper. You can use the present tense for recent research that is still a topic of current conversation—especially if your paper extends or contradicts that research. The cut-off point for "recent"—that is, the present—is "present conversation". The present perfect is a convenient way to suggest that the matter is still "open" and that your paper is going to make a contribution to it.

For example, if your paper proves a new stone theorem for the cake process, you could choose the tenses in your literature review like this:

Stone theorems have a long history. As long ago as 1978, B [B1978] proved the stone theorem for the B model. More recently, C and D [CD2014] have proved a stone theorem for the cake process in a random environment. They also provide a nice overview of existing results. In the present paper, we prove that stones in non-random cakes are indigestible.

The past tense suggests that B1978 is mostly of historical interest, a settled matter, now forgotten, or extremely well-known. It's done. Switching to the various forms of the present tense suggests that the research in those tenses is more directly relevant to the "present" paper—that is, yours.

This trick will probably have no effect on non-native speakers, who are usually oblivious to the difference between the simple past and the present perfect. And most native speakers do not consciously understand how they exploit these differences in tenses. But it's a very common technique at the beginning of a presentation to establish the scope of what is to follow. It sets the reader's expectations, even though most readers (and authors) aren't aware of it. You can see "establishing tense" used a lot at the beginning of newspaper stories, where an opening statement in the present perfect tense often indicates the range of time that the story will cover ("Election costs have risen 300% since 2000"), while an opening statement in the simple past tense often suggests a very short time-frame ("Stocks rose 2.1% on light trading [implicitly today].").


Disciplines which follow the APA's Publications Manual are sternly (and to my mind ludicrously) literal-minded about such temporal references, but to the best of my knowledge everybody else in academe accepts the ancient convention that a text which still 'speaks' to a present-day audience does so in the present tense.

However: if you're going to shift your tense in mid-stream, you should have a reason for doing so, and you should provide it; if you don't, you leave your readers wondering why you shifted—and quite possibly inferring a reason which you did not intend. In your case, for instance, a reader might conclude that B78 is a work of merely historical interest, while CD14 may still be profitably consulted by contemporary readers.

  • Another point that strikes me as odd is that the second sentence seems to talk about the author (B) having proven something, while the third sentence seems to talk about what's in the paper (that C and D co-authored), which (besides of the shift of the tense) urged me to re-read the second sentence once again and found that both sentences seem to be about papers rather than authors. May 23, 2016 at 12:48
  • @DamkerngT. So in your opinion, you think if one uses past-tense, one is describing the author himself, e.g., what he did at what time, while if one uses present-tense, one is describing the things the author did, e.g., what exactly he did, and why the stuff he did is important. The different tenses lead readers to focus on different 'subjects', or, 'objects'? Am I understanding right?
    – Hua
    May 24, 2016 at 3:27
  • @Hua It wasn't quite like that, and you shouldn't read a paper like that. In our case, when I read the second sentence (B [B78] proved ...), it's just common sense to read it as "B (an author) proved something", even though [B78] would refer to a specific paper (alpha style). However, when I read the next sentence, C and D [CD14] not only prove ..., but also have a nice overview, even though the verb agreements suggests that the the subject is "C and D", the verb have made me wonder what the writer had in mind when writing that sentence. They can have an overview in a paper, of course. May 24, 2016 at 6:40
  • (cont.) but the way it's phrased, it sounds like the authors still have the overview with them, even right now, which made me wonder whether the writer (supposedly our OP) thought of the authors (C and D) or their paper when writing that sentence. -- Note that rephrasing the idea with another verb, provide, as suggested in another answer, can avoid this confusion. May 24, 2016 at 6:43

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