Roderick Chisholm

Roderick Chisholm was an American philosopher who taught at Brown University for most of his career and wrote influentially on epistemology, metaphysics, intentionality and ethics. In deontic logic he identified the contrary-to-duty paradox: standard systems cannot consistently represent what one ought to do once one has already failed in a primary duty. He also defended a foundationalist theory of knowledge and an agent-causal account of free action.

Key ideas

• Obligations that arise once a duty has been violated cannot be represented consistently in standard deontic logic.
• Knowledge rests on foundations: some beliefs are justified by how things appear to us.
• Free agents cause their actions as agents, not merely through prior events.
• Intentionality, the directedness of thought, is a mark of the mental.

Major works

• Perceiving: A Philosophical Study (1957)
• "Contrary-to-Duty Imperatives and Deontic Logic" (1963)
• Theory of Knowledge (1966)
• Person and Object (1976)

In the conversation

• Question Chisholm’s contrary-to-duty paradox: why exactly do four sensible sentences become inconsistent? Thandeka Mokoena · 3 replies
• Debate S5 is the right logic for metaphysical necessity Tomasz Wójcik · 6 replies