Summary
An affordance is what an environment offers a creature to do. A flight of steps affords climbing to an adult but not to a crawling infant. The psychologist James J. Gibson coined the word in 1966 and defined it in 1979: “The affordances of the environment are what it offers the animal, what it provides or furnishes, either for good or ill.” He and Eleanor J. Gibson developed it within ecological psychology.
It belongs neither to the object alone nor to the mind; in Gibson’s words it “points both ways, to the environment and to the observer”. Complexity practitioners use it to ask what a setting makes easier or harder.
Rationale
Part 1 calls cognition “embodied, ecological and distributed”. Affordance is the working part of ‘ecological’: surroundings invite some actions over others, and enough repeated invitations are how a cultural habit ‘sets’.