Imagine a big two-story house with 10 bedrooms, 8.5 bathrooms, and various specialized rooms (such as libraries, map rooms, dining rooms, and dens).  Oddly, there’s only one staircase in the whole house, connecting the den on the first floor to the library on the second.

The problem is to identify the rooms on an architectural diagram that let you go up to the second floor.  For many people, it’s sufficient to highlight the den, but consider somebody confined to a wheelchair: without a stairclimbing mechanism, the den fails to afford the ability to get to the second floor.

Pushing the example, let’s assume that our actor is indeed confined to a wheelchair, and there is an elevator in the first-floor kitchen.  How specific can you get when it comes to highlighting the things that afford the ability for our actor to go upstairs?  Highlighting the whole kitchen is a bit too rough, but the elevator itself is insufficient – there’s lots of wiring, a circuit breaker in the basement, a backup generator outside, power lines running to a power station, and eventually the water flowing down the Niagra River.

Finally, let’s simplify things with a futuristic elevator that requires no wiring and generates its own power.  Clearly, this elevator plays a part in affording our actor the ability to get to the second floor.  However, the design of the kitchen is also crucial: if the pathways to the elevator were too narrow, it would be impossible to navigate a wheelchair to the elevator in the first place.  Thus, there are different parts of the kitchen that fit together in a way that enables our actor.

Affordances are interesting phenomena when describing regions, because of their actor-dependence, their causal roots, and their basis in heterogeneous regional parts.  These features distinguish affordances from their relatively simpler kin, qualities.  Recent work has shown how to draw a line on a map that justifiably delimits a region characterized by a quality such as forested or populated.  It would be helpful to extend this ability to delimit regions that can be characterized as habitable, navigable, or defensible.

I hypothesize that recent work on construing dispositions as causal predications made true by processes is sufficient to establish a theory of affordances that meshes well with current work in ecological psychology.  Moreover, I argue that this theory would be suitable for extending granular theories of quality-based region delineation to encompass regions characterized by affordances.