Bipartite Theoretical-Practical Reasoning in John Broome

Theoretical reasoning pertains to belief, while practical reasoning pertains to action. John Broome defines practical reasoning in a way that draws it closer to theoretical reasoning; this form is referred to as Bipartite theoretical-practical reasoning in this paper. An analysis of Broome’s works shows that this type of reasoning has distinct characteristics: (1) it is first-order, focusing on the content of beliefs rather than relying on attitudes; (2) it rests on the interplay between belief and intention; and (3) it simultaneously involves Modus Ponens and instrumental inference. Michael Bratman, however, views practical reasoning as primarily cognitive rather than instrumental, which implies that rationality is based on mental states and that practical reasoning is not necessarily grounded in rational entailments. Through philosophical analysis of Broome’s and Bratman’s arguments, this paper concludes that a conflation weakens Bratman’s critique—highlighted by Zimmerman—of three distinct notions: intention to act, attempting to act, and intentional action. Nonetheless, Broome’s attempt to defend the non-cognitive nature of practical reasoning, even within the broader framework of Instrumental Rationality with Necessity (IRW), remains ambiguous and leaves questions that warrant further investigation.