These different notions of simplicity are not only conceptually distinct, they are often mutually incompatible or conflicting. Nowhere has this become more evident than in the chimpanzee theory of mind debate. The last few years have witnessed a huge controversy over the experimental results in this research area. A number of studies have shown that chimpanzees can use information regarding what a competitor has visual access to in order to decide whether or not to go for a reward (Hare et al. 2