Historians’ Fallacies: Toward a Logic of Historical Thought, David Hackett Fischer (1970)

Nunc pro tunc translates to “now for then,” and is apparently also a legal term. There is as well the concept of presentism in Philosophy. It’s unrelated to the concept as it’s used in literary and historical analysis. Surprisingly, that infallible source has a nice summery:

In literary and historical analysis, presentism is the anachronistic introduction of present-day ideas and perspectives into depictions or interpretations of the past. Some modern historians seek to avoid presentism in their work because they consider it a form of cultural bias, and believe it creates a distorted understanding of their subject matter.^[1] The practice of presentism is regarded by some as a common fallacy when writing about the past.

The Oxford English Dictionary gives the first citation for presentism in its historiographic sense from 1916, and the word may have been used in this meaning as early as the 1870s. The historian David Hackett Fischer identifies presentism as a fallacy also known as the “fallacy of nunc pro tunc“. He has written that the “classic example” of presentism was the so-called “Whig history“, in which certain 18th- and 19th-century British historians wrote history in a way that used the past to validate their own political beliefs. This interpretation was presentist because it did not depict the past in objective historical context but instead viewed history only through the lens of contemporary Whig beliefs. In this kind of approach, which emphasizes the relevance of history to the present, things that do not seem relevant receive little attention, which results in a misleading portrayal of the past. “Whig history” or “whiggishness” are often used as synonyms for presentism particularly when the historical depiction in question is teleological or triumphalist.^[2]