Birthday of Charles Sanders Peirce (1839)

Peirce was an American polymath: logician, philosopher, mathematician, and scientist. He invented existential graphs (a graphical logic system), made major contributions to the philosophy of pragmatism, and laid the foundations of statistical inference (the design of experiments, confidence intervals). He also worked on the mathematics of the four‑colour theorem and the theory of signs (semiotics). His work on the logic of relatives (relations) anticipated modern relational algebra and database theory. He was largely ignored in his lifetime and died in poverty.