In their recently published discussion of why humans reason, Hugo Mercier and Dan Sperber (2011a) pose a question that on its face appears be metaphysical in nature and, hence, suitable primarily for unverifiable speculation. However, as piece unfolds, one is left less with this perception of issues and more with an appreciation of authors' effort expand domain of reasoning beyond narrowly and commonly conceived epistemic functions social realm in which collective decision making is occurring and participants seek exercise influence. To that end, they advance view that the function of reasoning is argumentative and that from this perspective it serves to devise and evaluate arguments intended persuade (p. 57). In developing thesis, which initially comes across as excessive, authors eventually concede that persuasion is neither only function of reasoning nor exclusive motivation humans have when engaging in it. Rather, persuasion, they claim, is main function of and motivation for reasoning. Even this more inclusive characterization, however, still strikes one as excessive, as well as likely unnecessary derive benefit from insights which reading article exposes one in efforts understand reasoning as a form of human activity. The restrictions that Mercier and Sperber (2011a) impose on functions of reasoning and motivations behind it may be a reflection of seeming teleological origins of their perspective and clearly are a reflection of its grounding in evolutionary psychology. Irrespective of influences, claim that persuasion is main function of and motivation for reasoning, even if limited social situations in which two or more individuals are attempting arrive at a collective decision, seems impose a burden of proof that would be difficult satisfy. Why it is insufficient simply acknowledge that these aspects of reasoning make sense on intuitive grounds, have a certain resonance with many people's lived experience, have received limited scholarly attention, and may lead different understandings of what constitutes skill in reasoning, or lack thereof, among humans escapes me. Even authors appear be tentative in advancing claim: In principle, several effects of a trait may contribute fitness, and hence a trait may have more than a single function. Even then, it may be possible rank importance of different functions, and in particular identify a function for which trait is best adapted as its main function. (p. 59) Even if scholars could realistically satisfy rather formidable burden of proof for justifying claims concerning main function of reasoning and principal motivation for engaging in it, Mercier and Sperber (2011a) provide little guidance concerning how determine, let alone confirm, that reasoning is best adapted for enabling people exchange arguments that, on whole, make communication more reliable and hence more advantageous (p. 60). In fairness, it presumably was not their intention advise readers about design of pertinent investigations. On other hand, some indication of how best test hypothesis embedded in opening paragraph would be of value. At minimum, it would seem necessary for one have: (a) access large numbers of dyads and groups performing decision-making tasks in not only controlled research environments, but in naturalistic settings as well; (b) reliable methods for recording ongoing interaction of participants for duration of task; and (c) suitable measures of both various functions of reasoning, defined as the mental act of constructing or evaluating an argument that is at least partly explicit and must contain both a and reasons accept this conclusion (Mercier & Sperber, 2011b, p. …