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Construals of Decision Theory

My proposal: \begin{quote} Decision Theory (like Game Theory) specifies a model of action. Models can be construed in several different ways. Decision Theory says nothing about how the model should be construed. \end{quote} Alternatives exist. For instance, \citet{binmore:1994_playing} claims the axioms of game theory are tautologies; on his story, the games are the models.

model vs construal

Source: Godfrey-Smith

e.g. model of a house

Model of a house. Initially it’s aspirational [construal 1]. They you win the lottery. Same model can be construed as a plan [construal 2]. Later, when the house is built, you use it as a map of the house [construal 3]. Then you realise that people are quite similar and that what you thought was a unique design is something that lots of other people would also want, so you use the model to predict what others will want [construal 4].

another contrast:

model vs theory

‘Theories, as they are usually understood by philosophers, make claims about the world [...]

Models, in my sense, do not themselves say anything about the world.

Models are structures that can be used by scientists to say various different things about the world,

by means of commentaries that accompany models but are distinct from them’

\citep[p.~4]{godfrey-smith:2005_folk}.

Godfrey-Smith, 2005 p. 4

‘Two scientists can use the same model to help with the same target system while having quite different views of how the model might be representing the target system. I will describe this situation by saying that the two scientists have different construals of the model’

\citep[p.~4]{godfrey-smith:2005_folk}

‘one scientist might [construe] some model simply as an input-output device, as a predictive tool.

Another might [construe] the same model as a faithful map of the inner workings of the target system’

\citep[p.~4]{godfrey-smith:2005_folk}

Godfrey-Smith, 2005 p. 4

‘Basic facility with the folk-psychological model does not require using a particular construal of it. Many construals are possible.

And it is also possible to have facility with the model, and have a sense of which target systems are appropriate for it, while not having much of a construal at all’

\citep[p.~5]{godfrey-smith:2005_folk}.

Godfrey-Smith, 2005 p. 5

This is your position!

Decision Theory (like Game Theory) specifies a model.

Models can be construed in several different ways.

Decision Theory says nothing about how the model should be construed.

What construals of Decision Theory might be useful?

  1. As a device for identifying behavioural patterns (‘revealed preference theory’)
  2. As a reconstruction of everyday reasoning, by reflective human adults, about what to do
  3. As a normative ideal
  4. As a model of how folk model minds and actions (a meta-model)
  5. As a computational description of a psychological processs

Decision Theory (like Game Theory) specifies a model.

Models can be construed in several different ways.

Decision Theory says nothing about how the model should be construed.

If we look at game theory more generally, we find that game theoretic analysis has been applied to ‘the formation and propagation of patterns in microbial populations’ \citep[e.g.][]{reichenbach:2007_mobility}.

1. Applications range from microbial populations to countries.

2. The explanations are of the same type in every case.

3. The underlying processes probably differ.

4. Therefore, game theory is agnostic about processes.

The construals are different ... so the explanations differ significantly.

Decision Theory (like Game Theory) specifies a model.

Models can be construed in several different ways.

Decision Theory says nothing about how the model should be construed.

tension

ok, so did we resolve the tensions?

The range of applications of Decision Theory shows it is agnostic about processes.

Dickinson’s instrumental process is characterised by appeal to Decision Theory.