This chapter introduces the rationalist model of delusions. It begins by presenting John Campbell’s seminal proposal that delusions are caused top-down by pathological Wittgensteinian framework or hinge beliefs. After presenting Campbell’s rationalist account of delusions, the chapter raises and examines prominent objections by Tim Bayne & Elisabeth Pacherie as well as by Tim Thornton. The former make an important distinction between the aetiological top-down cognitive part and the epistemological rationalist framework part of Campbell’s account. The thesis that delusions are caused (...) top-down by pathological beliefs is not equivalent to the thesis that delusions are Wittgensteinian framework certainties. This chapter endorses this distinction. While the arguments against the top-down aspect are found to be more convincing – which motivates popular two-factor theories – the rationalist framework model of delusions is defended as an epistemologically promising account of delusion. Finally, this chapter examines a range of developments that have been made taking Campbell’s rationalism as a starting point. Most prominently the section examines Eilan’s early development of rationalism and Rhodes and Gipps’ proposal that delusions are not framework propositions but a product of their absence. (shrink)