The philosophy of conspiracy theories is a subfield of applied epistemology.
Over the last couple decades, a small group of philosophers began rigorously addressing the issue of whether or not conspiracy theories are a class of ideas, perhaps like miracles, that can be regarded as unwarranted simply because of the features by which they count as “conspiracy theories.”
Two seminal essays stand out: (1) In 1995, Charles Pigden convincingly challenged the relevance of Karl Popper’s highly influential critique of “the conspiracy theory of society.” (2) In 1999, in the Journal of Philosophy, Brian Keeley explicitly addressed the aforementioned question of whether or not conspiracy theories may be dismissed in a way analogous to David Hume’s critique of miracles.
Pigden’s arguments have stood up well, and his early essay has helped to legitimize the practice of taking conspiracy theories seriously in the academy. Keeley’s contribution is very different. Its value is in its stimulation of various responses, not in its own soundness or coherence, for it has been the subject of much criticism and disagreement.
The result is that two schools of thought have developed, which have been labeled “generalism” and “particularism.” The generalists think that there are general reasons—though they disagree about what these are—on the basis of which conspiracy theories as a group can judged to be unwarranted, without even considering the particulars of individual cases. The particularist deny this, arguing that each conspiracy theory ought to be judged on its own particular merits.
Obviously (to most people), the particularists are right. The reason this is (or should be) obvious is that all sides agree that some conspiracy theories have turned out to be true. The most often cited are: Watergate, Iran-contra, and Bush administration’s propagandistic effort to drum up support for the war in Iraq based on false pretenses.
For more on the particularists, see: Conspiracy Theory Theorists.
For abstracts of my own contributions see: My Work on Conspiracy Theories.