Template:Are You Sure/December 21

• ... that mathematician and philosopher Jan Łukasiewicz (21 December 1878 – 13 February 1956) invented new forms of propositional logic, including the principle of non-contradiction and the law of excluded middle?

•... that I Snow What You Did Last Shiver is a 1997 American action-adventure film about four young friends who must survive winter hardship one year after covering up a car accident in which a man froze to death?