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This lecture introduces two (of many) interface problems. These are problems which arise when actions are controlled by two or more representations that are not inferentially integrated. How is it possible that the two representations non-accidentally match?

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Interface Problems arise when one action (or event) is controlled by two or more representations that are not inferentially integrated.

The representations’ influence on a single action indicates that the outcomes they represent must at least sometimes non-accidentally match. (Unless there is to be nothing at all to coordinate the representations’ influence.)

The lack of inferential integration rules out the most straightforward way of explaining how non-accidental matches occur—namely, through processes of inference.

We must therefore ask, How are non-accidental matches possible? The question is an interface problem.

In this lecture we will identify two interface problems. These involve:

In addition to being a philosophical topic in their own right,[1] interface problems are important for both philosophical and psychological theories of action.

Prerequisites and What to Skip

This lecture depends on you having studied some sections from a previous lecture:

None of this lecture is required for the minimum course of study.

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inferential integration : For states to be inferentially integrated means that: (a) they can come to be nonaccidentally related in ways that are approximately rational thanks to processes of inference and practical reasoning; and (b) in the absence of obstacles such as time pressure, distraction, motivations to be irrational, self-deception or exhaustion, approximately rational harmony will characteristically emerge, eventually, among those states.
interface problem : An interface problem may arise when two kinds of representation sometimes non-accidentally match: the problem is to explain how such matches are possible.
match : [of outcomes] Two collections of outcomes, A and B, match in a particular context just if, in that context, either the occurrence of the A-outcomes would normally constitute or cause, at least partially, the occurrence of the B-outcomes or vice versa.
To illustrate, one way of matching is for the B-outcomes to be the A-outcomes. Another way of matching is for the B-outcomes to stand to the A-outcomes as elements of a more detailed plan stand to those of a less detailed one.
[of plan-like structures] In the simplest case, plan-like hierarchies of motor representations match if they are identical. More generally, plan-like hierarchies match if the differences between them do not matter in the following sense. For a plan-like hierarchy in an agent, let the self part be those motor representations concerning the agent's own actions and let the other part be the other motor representations. First consider what would happen if, for a particular agent, the other part of her plan-like hierarchy were as nearly identical to the self part (or parts) of the other's plan-like hierarchy (or others' plan-like hierarchies) as psychologically possible. Would the agent's self part be different? If not, let us say that any differences between her plan-like hierarchy and the other's (or others') are not relevant for her. Finally, if for some agents' plan-like hierarchies of motor representations the differences between them are not relevant for any of the agents, then let us say that the differences do not matter.
[of motivational states] Two motivational states match in a particular context just if, in that context, the actions one would cause and the actions the other would cause are all proper ways of fulfilling both motivational states.
motor representation : The kind of representation characteristically involved in preparing, performing and monitoring sequences of small-scale actions such as grasping, transporting and placing an object. They represent actual, possible, imagined or observed actions and their effects.
primary motivational state : A state such as hunger, thirst, satiety, aversion or sexual arousal. Primary motivational states are closely linked to biological needs. They are not all acquired through learning; and learning has limited effects on them, although classical conditioning can modify them (Capaldi, Hunter, & Lyn, 1997).


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  1. See Mylopoulos & Pacherie (2016); Fridland (2016); Shepherd (2019); Christensen (2021); or Ferretti & Zipoli Caiani (2021). ↩︎