Explanation I use in comments on student papers:
It is conventional in critical essays to use the analytical present tense (sometimes called “literary present”) when analyzing a work, even if the author or work is from the past. (The work is still present for us to look at.) So when discussing an essay or book, for example, you would usually stay with a consistent present tense–“The essay argues that . . . ,” “The authors of the essay believe that . . . ,” etc. (NOT “The authors of the essay believed that”).
The exception is when your discussion deliberately places the analysis of a work in the context of a historical event or period (or compares writers as historical figures). For example, if you are writing about Milton’s work in relation to the history of England, then the following is correct: “Milton wrote his epic poem when England was just coming out of crisis.” You would stay with the historical past tense so long as you were working in the historical mode. When you then turn to close-reading the work, you would then switch to literary present.
(Note: in complex discussions when a critic oscillates between analysis and historical explanation, there are gray areas where it is difficult to know which tense to use. Just aim for what feels like consistency.)
