Charles Sanders Peirce (1839–1914) was an American logician, mathematician and scientist. British philosopher Bertrand Russell said that Peirce was “certainly the greatest American thinker ever”^[1].

Pragmaticism

Along with William James, Peirce is considered a father of pragmatism. However, this view actually comes from a misinterpretation of Peirce’s early writings. As Bertrand Russell puts it, the current conception of pragmatism “stems not from Peirce, but from what William James thought Peirce was saying”^[2]. Peirce later clarified his poition and gave it the label of ‘pragmaticism’ to try and separate his own position from James’ interpretation.

Peirce Arrow

Charles Sanders Peirce showed that a joint denial, otherwise known as a nor operation can be used to define every other truth-functional logical operator.

The symbol for the joint denial ( ↓ ) is known as the Peirce arrow after Charles Sanders Peirce.

Peirce also demonstrated that an alternative denial could also be used for the same purpose by 1880. However, Henry M. Sheffer is partly credited with this discovery after he independantly arrived at this result and published it in 1913. Peirce's paper demonstrating the same was not published until 1933. The symbol for the alternative denial, ( | or ↑ ) is called the Sheffer stroke.

1. Russell, Bertrand. Wisdom of the West. Ed. Paul Foulkes. London: Crescent, 1977. p. 276. (