This paper seeks to carve out a distinctive category of conspiracy theorist, and to explore the process of becoming a conspiracy theorist of this sort. Those on whom I focus claim their beliefs trace back to simply trusting their senses and experiences in a commonsensical way, citing what they take to be authoritative firsthand evidence or observations. Certain flat Earthers, anti-vaxxers, and UFO conspiracy theorists, for example, describe their beliefs and evidence this way. I first distinguish these conspiracy theorists by (...) contrasting them with another group that has recently received a lot of attention from the media, philosophers, and academics more broadly. I then dig more deeply into the nature of these conspiracy theorists’ epistemic self-understanding, in order to give an account of the process by which one becomes such a conspiracy theorist. I conclude with some takeaways and implications: first, I explore the implications of my account for whether these conspiracy theorists’ beliefs are rational; then, I argue that my account has practical takeaways about counteracting beliefs in misinformation, since strategies appropriate to this kind of conspiracy theorist may not be the same ones that are appropriate for other kinds. (shrink)