When Rational Reasoners Reason Differently

Different people reason differently, which means that sometimes they reach different conclusions from the same evidence. We maintain that this is not only natural, but rational. This chapter explores the epistemology of that state of affairs. First it canvasses arguments for and against the claim that rational methods of reasoning must always reach the same conclusions from the same evidence. Then it considers whether the acknowledgment that people have divergent rational reasoning methods should undermine one’s confidence in one’s own reasoning. Finally it explores how agents who employ distinct yet equally rational methods of reasoning should respond to interactions with the products of each others’ reasoning. The chapter finds that the epistemology of multiple reasoning methods has been misunderstood by a number of authors writing on epistemic permissiveness and peer disagreement.

Small Steps and Great Leaps in Thought

We are justified in employing the rule of inference Modus Ponens (or one much like it) as basic in our reasoning. By contrast, we are not justified in employing a rule of inference that permits inferring to some difficult mathematical theorem from the relevant axioms in a single step. Such an inferential step is intuitively “too large” to count as justified. What accounts for this difference? This chapter canvasses several possible explanations. It argues that the most promising approach is to appeal to features like usefulness or indispensability to important or required cognitive projects. On the resulting view, whether an inferential step counts as large or small depends on the importance of the relevant rule of inference in our thought.

Isolating Correct Reasoning

This chapter tries to do three things. First, it argues that rules of correct reasoning do not always preserve justification: if you begin with a justified attitude, and reason correctly from it, it can nevertheless happen that you’ll arrive at an unjustified attitude. Second, it argues that rules of correct reasoning do not even correspond to permissions of “structural rationality”: it is not always structurally permissible to base an attitude on other attitudes from which it follows by correct reasoning. Third, from these observations it tries to build a somewhat positive account of correct reasoning as a more sui generis notion irreducible to either justification or structural rationality. This account vindicates an important unity of theoretical and practical reasoning as well as a qualified version of the thesis that deductive logic supplies rules of correct reasoning.

Inference, Agency, and Responsibility

What happens when we reason our way from one proposition to another? This process is usually called “inference” and this chapter examines its nature. It revisits the author’s earlier attempts to explain the nature of the process of inference, and tries to further clarify why we need the type of “intellectualist” account of that process that he has been pursuing. In the course of doing so, the chapter traces some unexpected connections between our topic and the distinction between a priori and a posteriori justification, and tries to draw some general methodological morals about the role of phenomenology in the philosophy of mind.

A Linking Belief is Not Essential for Reasoning

In reasoning, you acquire a new conclusion attitude on the basis of premise attitudes. It is commonly thought that an essential feature of reasoning is that you have a linking belief, which is a belief that the premises imply the conclusion. This chapter shows that a linking belief is not essential for reasoning. A genuinely essential feature of reasoning is that you acquire the conclusion attitude by following a rule. A linking belief may be a necessary feature of theoretical reasoning, because it may be a consequence of having the disposition to follow a rule. But it is not essential for reasoning, which is to say that it does not contribute to making the process reasoning. For other sorts of reasoning including practical reasoning, a linking belief is not even necessary.

Questions about the Nature and Value of Reasoning

This chapter provides a brief and informal introduction to some of the central philosophical questions about reasoning. Among the questions discussed are: What distinguishes reasoning from other mental processes, such as free association or daydreaming? Does reasoning require a recognition that one’s premises support one’s conclusion? Is reasoning something that we do, and as such, something that we can be held responsible for? If so, how should we understand the role that sub-personal information processing plays in much of our ordinary reasoning? How can we characterize the difference between good reasoning and bad, or between correct and incorrect reasoning? Are there rules for correct reasoning? If so, do they go beyond minimal coherence constraints, such as the constraint against believing contradictions? How should we understand reasoning that departs from the paradigm of deductive reasoning? Do the same rules apply to all of us? Can two thinkers reason well from the same premises and yet arrive at incompatible conclusions? This introductory chapter provides a brief overview of how the essays in this collection address these and other questions about reasoning.

Inference without Reckoning

What kinds of transitions in the mind constitute inference? A powerful idea, found in Frege, is that inference from state X to state Y requires the inferrer to represent in some way that X supports Y. This chapter argues that this model of inference would be stable and motivated only if the inferring subjects met a self-awareness condition, in which they are aware or can become aware by reflection of what they are inferentially responding to and why. It argues against the model on the grounds that a large class of mental transitions meet the hallmarks of inference yet fail to meet the self-awareness condition. It argues that a better model for inference drops the self-awareness condition and allows that subjects regularly draw inferences even when they do not represent what they are inferentially responding to or why.

Sovereign Agency

This chapter argues that a constitutive feature of authority over oneself is intentions functioning as content-independent reasons not to reopen deliberations and as content-independent reasons to do as intended. It first argues that deliberations and intentions have certain functional roles, namely, completed deliberations function as reasons to intend, intentions function as reasons not to reopen deliberations about whether to act as intended, and intentions also function as reasons to act as intended. Second, it argues that if any form of authority is possible at all, it must be an agent’s authority over herself. We are, in short, authorities over ourselves and we exercise this authority by commanding ourselves to act. These commands are intentions. The chapter concludes that either sound deliberations and the intentions they produce are reasons or there is no such thing as agential authority.

With Power Comes Responsibility

Philosophers often take it for granted that the requirements of rationality are universal, that whatever rationality requires of a subject’s reasoning is exactly what it would require of any other subject’s reasoning. This is plausible for some requirements: we all ought to respect modus ponens in our reasoning, for example. However, this chapter argues that many important cases are not like this. These are cases where the rational status of one’s reasoning depends on whether one has a certain cognitive capacity that one is in a position to exercise. The reasoning of one thinker who has a certain cognitive capacity can be rationally appropriate, while the exact same reasoning would not be rationally appropriate for subjects who lack that capacity. If this is correct then what rationality requires of a thinker depends (in part) on what cognitive capacities she possesses. Certain cognitive powers bring with them certain distinctive rational responsibilities.

The Question of Practical Reason

Practical reasoning is often said to involve undertaking to settle the practical question of how we are to act. But what is this “question?” One view—that it is a theoretical question with a practical subject matter—cannot capture both the correct responsiveness aspect and the authoritative aspect of practical reason. An alternative holds that it is a distinctively practical kind of question—the question of what to do—that is distinct from the question of what one will do and the question of what one ought or has reason to do. Such a view can easily accommodate the authoritative aspect of practical reason. This chapter argues that it can also accommodate the correct responsiveness aspect once we appreciate that correct answers to the question of what to do depend exclusively on our actual attitudes. It concludes by considering the implications of this view for several important issues in meta-ethics and the philosophy of normativity.