CONCEPT
Functionings and Capabilities
Sen's foundational distinction between what a person does or is (functioning) and what she is substantively free to do or to be (capability) — the analytical engine of capability theory.
A functioning, in Sen's framework, is an achieved state of being or doing: being well-nourished, being educated, participating in community life, exercising professional judgment. A capability is the real freedom to achieve a functioning — the substantive opportunity whether or not it is exercised. The distinction is the analytical engine of the entire framework. It matters because a person can possess a capability without exercising it, and the freedom to choose not to exercise a capability is itself valuable. Applied to AI, the distinction reveals what output metrics systematically miss: a tool can expand what a person does (the functioning set) while contracting what a person could do (the capability set).
In The You On AI Field Guide
The distinction's power comes from what it permits the evaluator to see. A student who uses AI to generate an essay has achieved a functioning — the essay exists. But the capability question is prior: has the student's capability of writing expanded or contracted? If