German logicians

Christoph von Sigwart (28 March 1830 – 4 August 1904) was a German philosopher and logician. He was the son of philosopher Heinrich Christoph Wilhelm Sigwart (31 August 1789 – 16 November 1844).

Kurt Grelling (2 March 1886 – September 1942) was a German logician and philosopher, member of the Berlin Circle.

Arthur Scherbius (30 October 1878 – 13 May 1929) was a German electrical engineer who invented the mechanical cipher Enigma machine. He patented the invention and later sold the machine under the brand name Enigma.
Scherbius offered unequalled opportunities and showed the importance of cryptography to both military and civil intelligence.

Paul Gerhard Natorp (24 January 1854 – 17 August 1924) was a German philosopher and educationalist, considered one of the co-founders of the Marburg school of neo-Kantianism. He was known as an authority on Plato.