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1. Introduction

Yesterday’s post developed a reason-responsive consequentialist theory of rational inquiry for bounded agents. Today’s post gives three arguments for that view.

2. The argument from minimal criteria

A good theory of bounded rationality should satisfy at least three minimal criteria.

First, it should be tradeoff-sensitive. Bounded agents have limited resources that must be traded off within and between inquiries and other activities. We cannot ignore tradeoffs, so a good theory should tell us how to make them.

Second, it should be stakes-sensitive. For example, it should say that ceteris paribus, it is better to think quickly about less important matters and slowly about more important matters.

Third, it should explain the irrationality of many instances of stereotyping, despite a highly uncomfortable relationship between stereotypes and seemingly rational heuristics. I won’t defend an agent who concludes that a woman in a boardroom is a secretary, though I might defend an agent who concludes that a tree in my home town is a pine.

I argue that the reason-responsive consequentialist view is our best hope for satisfying the minimal criteria. Consequentialists give precise and explanatory accounts of stakes and tradeoffs, and account for the irrationality of stereotyping by citing the magnitude of risked harms.

3. The explanatory argument

Consequentialists have a consequentializing program. We want to develop detailed, plausible, and explanatorily powerful accounts of normative data that other approaches struggle to accommodate. The explanatory argument for consequentialism takes these explanatory successes as evidence for a consequentialist approach.

In particular, I consider three data:

Norms of clutter avoidance say that agents are rationally required to avoid forming junk beliefs and to do what they can to purge existing junk beliefs from long-term memory. I show how my view recovers all three classic arguments for clutter avoidance made by Gilbert Harman: agents need to avoid (a) wasting effort, and (b) overwhelming limited storage and (c) retrieval capacities in memory.

Norms of friendship hold that agents are rationally required to show some partiality in thinking about friends. I argue that this is best treated as a datum about inquiry rather than belief, and show how a consequentialist approach gives a more moderate account of duties of friendship in inquiry than some competing approaches.

Norms of logical non-omniscience say that agents are rationally required to have some degree of logical omniscience, but not perfect logical omniscience. Most theorists have struggled to give precise and plausible accounts of the degree of logical omniscience that is required. I draw on existing discussions of bounded rationality in the context of chess, a game which is logically trivial but computationally intractable, to show how a consequentialist account can give precise and plausible constraints on the degree of logical omniscience that is required.

4. The vindicatory argument

We saw in Part 2 of this series that theories of bounded rationality are vindicatory, showing how many seeming irrationalities are nothing of the sort. A good theory of bounded rationality should be able to deliver vindicatory explanations that others cannot. I focus on two case studies.

The first is anchoring and adjustment. If I ask you to name the date of George Washington’s birth, you might anchor on a salient value (say, the year 1776 in which the Declaration of Independence was signed) and iteratively adjust your estimate by considering items of information bearing on Washington’s age. If you did this, your estimate would likely be close to the value, but would show an anchoring bias: it would be (on average) more likely to lie in the direction of the anchor. I argue that many anchoring biases result from fully rational processes of anchoring and adjustment.

The second is the Wason selection task. This is a classic task in the psychology of reasoning which asks agents to turn cards in order to test a hypothesis. The Wason selection task has classically been interpreted as a test of logical reasoning, a construal on which most agents perform quite poorly. However, a recently popular probabilistic reconstrual of the task does better. I show how a consequentialist re-interpretation of this vindicatory explanation allows us to extend it in a variety of plausible and correct directions, whereas by contrast most of the probabilistic reconstrual is difficult to motivate outside of a consequentialist framework.

Insofar as we want to recover these vindicatory explanations and others like them, the reason-responsive consequentialist view is a good way to go.

5. Looking ahead

Yesterday’s post developed a theory of rational inquiry and today’s post defended it. The final order of business is to use this theory to defend, clarify and apply the claims about bounded rationality introduced in the second post and to shed light on other questions about bounded rationality, the Standard Picture, and the epistemology of inquiry. I take up this task in the next post.