A growing consensus in the literature on agentive modals has it that ability modals like ‘can’ or ‘able to’ have a dual, i.e. interpretations of ‘must’ or ‘cannot but’ which stand to necessity as ability stands to possibility. We argue that this thesis (which we call ‘Agentive Duality’) is much more controversial than meets the eye. While Agentive Duality follows from the orthodox possibility analysis of ability given natural assumptions, it sits uneasily with a wide range of alternative proposals which are unified by the idea that ability requires control. In particular, we show that against the background of a control requirement on ability, Agentive Duality can be used to derive absurd predictions featuring this dual. Far from being a purely definitional thesis, Agentive Duality thus affords a new lens through which to assess the long-standing debate between possibility analyses of ability and their discontents.

关于代理模态的文献中越来越多的共识是，像“可以”或“能够”这样的能力模态具有双重性，即对“必须”或“不能但”的解释，它们代表必要性，因为能力代表可能性。我们认为，这个论点（我们称之为“能动二元性”）比看上去更具争议性。虽然能动二元性源于对给定自然假设的能力的正统可能性分析，但它不安地与广泛的替代建议相结合，这些建议被能力需要控制的想法统一起来. 特别是，我们表明，在对能力的控制要求的背景下，智能对偶性可用于得出具有这种对偶性的荒谬预测。因此，能动二元性远不是一个纯粹的定义论题，它提供了一个新的视角，通过它来评估能力的可能性分析与他们的不满之间长期存在的争论。