Epistemology: how knowledge is sought and gained; the validity of knowledge gained, and the distinction between justified belief and opinion.
Epistemological fallacies are flawed conclusions or beliefs, which are flawed because the means of arriving at the conclusions or beliefs are flawed.
I will give an actual example of the epistemological fallacy which has recently come to my attention through my contacts. (This is the first example in a semi-regular series which I will call Faculty Follies - readers of this blog are encouraged to alert me to any examples they might come across.)
A certain working party within a nameless faculty within a nameless university (let's call it the Faculty of Social Sciences at Walladumpdung University) is charged with coming up with a "workload formula" for quantifying academic output. The Work Working Party (WWP), in its wisdom, decides that writing and publishing a book represents 20% of an academic's output over the course of a year (the equivalent of one day a week). This figure is duly enshrined into a formula and is officially regarded as a reasonable benchmark.
A few moments' serious consideration of this figure reveals that it is a preposterous fantasy. A fantasy which is so unrealistic that it borders on the infantile. Consider for example the actual output of outstandingly successful and highly productive authors.
Paul Theroux has written nine books in the decade from 1996-2005 (novels and travel); and Bill Bryson has written eight books in the same decade (non-fiction and travel). According to the esteemed scholars in the WWP, each author has been working (the equivalent of) less than one day a week. Indeed, according to the standards set by the Workload Working Party, both authors have been woefully unproductive, and each of them should have written 50 books over the period in question.
We can infer that the epistemological fallacy is involved here because of the sheer absurdity of the conclusion drawn from the "research". Perhaps the WWP should have found out how productive full-time and highly successful professional authors actually are before they came up with this risible figure.