There has been a lively philosophical debate about the nature of conspiracy theories and their epistemic status going on for some years now. This debate has shed light, not only on conspiracy theories themselves, but also, in the process, on a variety of issues in social epistemology, political philosophy, and the philosophy of religion.

Traditional secular conspiracy theories and explanations of worldly events in terms of supernatural agency share interesting epistemic features. This paper explores what can be called “supernatural conspiracy theories”, by considering such supernatural explanations through the lens of recent work on the epistemology of secular conspiracy theories. After considering the similarities and the differences between the two types of theories, the prospects for agnosticism both with respect to secular conspiracy theories and the existence of God are then considered. Arguments regarding secular conspiracy theories suggest ways to defend agnosticism with respect to God from arguments that agnosticism is not a logically stable position and that it ultimately collapses into atheism, as has been argued by N. Russell Hanson and others. I conclude that such attacks on religious agnosticism fail to appreciate the conspiratorial features of God's alleged role in the universe.

The article sketches a theoretical model which explains how it is possible that fundamentalist beliefs can emerge as a result of an individual rational adaptation to the context of special living conditions. The model is based on the insight that most of our knowledge is acquired by trusting the testimony of some kind of authority. If a social group is characterized by a high degree of mistrust towards the outer society or other groups, then the members of this group will rely solely on the authorities of their own group for their acquisition of knowledge. In this way they can adopt a corpus of beliefs which may seem absurd from an external point of view. However, they may be locked in a “fundamentalist equilibrium” in which particularistic trust, common sense plausibility, epistemic seclusion, social isolation and fundamentalist beliefs are mutually reinforcing - and in which individuals who adopt the “fundamentalist truths” of their group do not behave more irrationally than individuals in an open society who accept the “enlightened” worldview of their culture.

Following Clarke (2002), a Lakatosian approach is used to account for the epistemic development of conspiracy theories. It is then argued that the hypercritical atmosphere of the internet has slowed down the development of conspiracy theories, discouraging conspiracy theorists from articulating explicit versions of their favoured theories, which could form the hard core of Lakatosian research programmes. The argument is illustrated with a study of the “controlled demolition” theory of the collapse of three towers at the World Trade Center on September 11, 2001.

The typical explanation of an event or process which attracts the label ‘conspiracy theory’ is an explanation that conflicts with the account advanced by the relevant epistemic authorities. I argue that both for the layperson and for the intellectual, it is almost never rational to accept such a conspiracy theory. Knowledge is not merely shallowly social, in the manner recognized by social epistemology, it is also constitutively social: many kinds of knowledge only become accessible thanks to the agent's embedding in an environment that includes other epistemic agents. Moreover, advances in knowledge typically require ongoing immersion in this social environment. But the intellectual who embraces a conspiracy theory risks cutting herself off from this environment, and therefore epistemically disabling herself. Embracing a conspiracy theory therefore places at risk the ability to engage in genuine enquiry, including the enquiry needed properly to evaluate the conspiracy theory.

It is widely believed that to be a conspiracy theorist is to suffer from a form of irrationality. After considering the merits and defects of a variety of accounts of what it is to be a conspiracy theorist, I draw three conclusions. One, on the best definitions of what it is to be a conspiracy theorist, conspiracy theorists do not deserve their reputation for irrationality. Two, there may be occasions on which we should settle for an inferior definition which entails that conspiracy theorists are after all irrational. Three, if and when we do this, we should recognise that conspiracy theorists so understood are at one end of a spectrum, and the really worrying form of irrationality is at the other end.

In this paper I embrace what Brian Keeley calls in “Of Conspiracy Theories” the absurdist horn of the dilemma for philosophers who criticize such theories. I thus defend the view that there is indeed something deeply epistemically wrong with conspiracy theorizing. My complaint is that conspiracy theories apply intentional explanations to situations that give rise to special problems concerning the elimination of competing intentional explanations.

Conspiracy theories should be neither believed nor investigated - that is the conventional wisdom. I argue that it is sometimes permissible both to investigate and to believe. Hence this is a dispute in the ethics of belief. I defend epistemic “oughts” that apply in the first instance to belief-forming strategies that are partly under our control. But the belief-forming strategy of not believing conspiracy theories would be a political disaster and the epistemic equivalent of self-mutilation. I discuss several variations of this strategy, interpreting “conspiracy theory” in different ways but conclude that on all these readings, the conventional wisdom is deeply unwise.