  Ockham and John Buridan’s accounts of thought are on the one hand very similar, but on the other hand there are fundamental differences between them. This is particularly true about their view of mental representation. A case in point is their views of singular thought. They both start out from the same idea, that is, that thinking something singular is having a singular concept in mind, but they disagree fundamentally on what a singular concept looks like and foremost on how it manages to latch onto the world. On Ockham’s account a concept is singular because its cause was proper, as he calls it, and proper causes are necessarily tied to one object. But on Buridan’s account, a singular concept is singular because of its complexity. (Meaning pure semantic complexity, according to Klima 2001: xxxviii–xlii and 2009: 40–56) It has a descriptive content that enables it to narrow down its signification to only one thing. (For the significance of this difference from Ockham, see Klima 2009: 69–89)