 A comparatively early and influential statement of a manipulability theory which assigns a central role to human agency is due to von Wright (1971; see  An Early Version of an Agency Theory  for further discussion). However, this entry will focus on the more recent version of an agency theory developed by Peter Menzies and Huw Price (1993) (also discussed in a series of papers written by Price alone [1991, 1992). Menzies’ and Price’s basic thesis is that: