1905 – 1967
Henry S. Leonard (1905–1967) was an American philosopher who made foundational contributions to formal logic and mereology. He is best known for co-developing the Calculus of Individuals with Nelson Goodman, a landmark formal treatment of part-whole relations. His work engaged deeply with nominalism, the logic of inscriptions, and the ontology of linguistic entities.
Co-authored 'The Calculus of Individuals and Its Uses' (1940) with Nelson Goodman, a foundational text in mereology
Developed a nominalist account of linguistic inscription and token identity
Contributed to formal treatments of part-whole relations as an alternative to set theory
Worked on the logical analysis of reference and the individuation of word-tokens from physical inscriptions