Template:Are You Sure/October 6

• ... that philosopher Thomas Reid believed that common sense (in a special philosophical sense of sensus communis) is, or at least should be, at the foundation of all philosophical inquiry, and that the foundations upon which our sensus communis are built justify our belief that there is an external world?

• ... that mathematician Benjamin Peirce introduced the terms idempotent and nilpotent in 1870 to describe elements of associative algebras?