Gerardus Heymans (1857-1930) was a famous philosopher, psychologist, a follower of Fechner's idea of psychic monism, and from 1890 to 1927 a Professor at Groningen University.

His student Johannes Jacobus Poortman could not agree with his monistic point of view and formulated the concept of hylic pluralism (in Dutch hylisch pluralisme ).

On June 11, 1944, the Heymans-Genootschap , an organisation for the continuation of his work, was established.