 Certainty, or the attempt to obtain certainty, has played a central role in the history of philosophy. Some philosophers have taken the kind of certainty characteristic of mathematical knowledge to be the goal at which philosophy should aim. In the Republic, Plato says that geometry “draws the soul towards truth and produces philosophic thought by directing upwards what we now wrongly direct downwards” (527b). Descartes also thought that a philosophical method that proceeds in a mathematical way, enumerating and ordering everything exactly, “contains everything that gives certainty to the rules of mathematics” (Discourse on the Method, PW 1, p. 121). Other philosophers have adopted different models for how to best understand certainty. For example, Aristotle and Aquinas take scientific explanation to be essential to certainty (see Pasnau 2017, pp. 5–7), while Al-Ghazālī thought that certainty arose out of religious practice (see Albertini 2005). For many empiricists, certainty with respect to empirical matters is to be found in basic beliefs that are grounded in some fundamental aspect of perceptual experience (see, e.g., Lewis 1952).