 George Bealer (1996, 1998, 1999a,b, 2002; Bealer in Bealer &amp; Strawson 1992) integrates understanding and intuition in order to explain knowledge of modality. As an intuitionist, Bealer takes intuitions to count as (prima facie) evidence. According to Bealer’s Modal Reliabilism “something is a basic source of evidence iff it has an appropriate kind of reliable tie to the truth” (Bealer 1999a: 34). He articulates a notion of determinate understanding (or determinate concept possession) that casts light on how our modal intuitions can be appropriately truth-tracking and, thus reliable. Roughly, determinate understanding (or concept possession) excludes any partial misunderstanding or incomplete understanding of the concept(s) in question. It ultimately amounts to a form of understanding that is incorrigible by improvement of the subject’s cognitive condition or conceptual repertoire (see Bealer 2002: 104). So, if we determinately understand a specific concept, we will have truth-tracking intuitions (and therefore also truth-tracking modal intuitions) about propositions in which this concept is involved. For example, it is because one determinately understands the concepts of a square and a triangle, that their intuition that nothing can be both a square and a triangle is truth-tracking and, thus, provides them with evidence that it is impossible for something to be both a square and a triangle.