Spontaneous inferences are unconscious, automatic, and apparently ubiquitous. Research has documented their variety (particularly in the social domain) and impact on memory and judgment. They are good candidates for Mercier and Sperber's (M&S's) “intuitive beliefs.” Forming spontaneous inferences is highly context sensitive, varying with the perceiver's conscious and unconscious goals, and implicit and explicit theories about the domain in question.

Mercier and Sperber (M&S) argue that reasoning is social and argumentative, and that this explains many apparently irrational judgment phenomena. We look at the relationship between interpersonal and intrapersonal argumentation and discuss parallels and differences from the perspective of query theory, a memory-based model of constructive preferences. We suggest an important goal is to integrate models across inference and preference.

Mercier & Sperber (M&S) argue for their argumentative theory in terms of communicative abilities. Insights can be gained by extending the discussion beyond human reasoning to rodent and robot navigation. The selection of arguments and conclusions that are mutually reinforcing can be cast as a form of abductive reasoning that I argue underlies the construction of cognitive maps in navigation tasks.

The empirical research on the psychology of argumentation suggests that people are prone to fallacies and suboptimal performance in generating, comprehending, and evaluating arguments. Reasoning and argumentation are interrelated skills that use many of the same cognitive processes. The processes we use to convince others are also used to convince ourselves. Argumentation would be ineffective if we couldn't reason for ourselves.

Deliberative democracy is one of the best designs that could facilitate good public policy decision making and bring about epistemic good based on Mercier and Sperber's (M&S's) theory of reasoning. However, three conditions are necessary: (1) an ethic of individual epistemic humility, (2) a pragmatic deflationist definition of truth, and (3) a microscopic framing power analysis during group reasoning.

Having defended the usefulness of our definition of reasoning, we stress that reasoning is not only for convincing but also for evaluating arguments, and that as such it has an epistemic function. We defend the evidence supporting the theory against several challenges: People are good informal arguers, they reason better in groups, and they have a confirmation bias. Finally, we consider possible extensions, first in terms of process-level theories of reasoning, and second in the effects of reasoning outside the lab.