Are spatial terms rooted in geometry or force-dynamics? Yes.

Theories of spatial term meanings often focus on geometric properties of objects and locations as the key to understanding meaning. For example, in English, "The cat is on the mat" might engage geometric properties characterizing the figure ('cat', a point) and the ground ('mat', a plane) as well as the geometric relationship between the two objects ('on', + vertical, 0 distance from ground object). However, substantial literature suggests that geometric properties are far from sufficient to capture the meanings of many spatial expressions, and that instead, force-dynamic properties of objects that afford containment or support relationships may be crucial to the meanings of those expressions. I will argue that both approaches are needed to understand the variety of spatial terms that appear in language and further, that spatial terms fall into two distinct sets, one represented by geometric properties of figure and ground and their spatial relationships, and the other by the force-dynamic properties of objects and their relationships. This division of labor within spatial terms has many consequences, with the two types differing in the nature of the acquisition problem and likely learning mechanisms, the extent and kind of cross-linguistic variation that has been observed, and the application of pragmatic principles to spatial terms. Speculatively, the two types may also be rooted in different cognitive systems and their neural substrates.