The idea of doubt seems to serve as a privileged dispositif in the contemporary social scientific imaginary. Its evidence is in the requisite denunciation of 'Cartesianism' as an obligatory course of social scientific argumentation; there seems to be a pressing need to recall cogito again and again as an errancy. Academic commentaries on the phenomenon of conspiracy theory seem to be already rehearsed in this 'sacrificial' complex in which the philosophy of doubt is caught; cogito and conspiracy theory are assigned a common scapegoat-like fate in this regime of thought. 'In the evil of the scapegoat', wrote Jacques Derrida, 'the sacrificer expels what is vilest in itself'. To dwell on cogito and conspiracy theory in this climate, then, is to interrogate the rhetorical unity of social science's epistemic authority. I demonstrate the descriptive challenge this entanglement poses through an ethnographic case of conspiratorial doubt among a group of Pennsylvania (ex-)miners.