Kinds of Assumptions and Their Truth: Shaking an Untwisted F‐Twist
在Musgrave区分三种假设类型的基础上，进一步澄清不同假设的形式同一性，引入可检测性、可忽略性、领域和可接受性等新区分，并指出早期步骤假设的特殊性，为经济学假设的真实性争论提供更细致的分析框架。
In an insightful article published in this journal, Alan Musgrave (1981) has argued that once we distinguish between three types of assumptions, Milton Friedman’s F‐twist – according to which the truth of the assumptions of an economic theory is irrelevant to its acceptability – can be untwisted. It is shown that once we bring in more clarity on the formal identity of the different kinds of assumptions, Musgrave’s contribution can be further defined: distinctions can be drawn between detectability and negligibility assumptions, and between domain and acceptability assumptions; the suggested gap between as‐if assumptions and other kinds can be removed; another type, that of joint neglibility assumption, can be introduced; the untwisting of the F‐twist can be accepted in all cases except in the case of early‐step (heuristic) assumptions; and the art of paraphrase is shown to constitute the basis for Musgrave’s strategy and to have limits.