Only other humans, never material things, can oppress a person

Evidence

Such a situation is never natural: man is never oppressed by things; in any case, unless he is a naive child who hits stones or a mad prince who orders the sea to be thrashed, he does not rebel against things, but only against other men. The resistance of the thing sustains the action of man as air sustains the flight of the dove; and by projecting himself through it man accepts its being an obstacle; he assumes the risk of a setback in which he does not see a denial of his freedom. — Simone de Beauvoir, The Ethics of Ambiguity, 86

Categorization

• DEFINE: Distinguishes natural obstacles (which sustain action) from human oppression, and shores up the definition of oppression as always man-made.