Home > Less Wrong and decision theory > Errata to Newcomb’s Problem post

Errata to Newcomb’s Problem post

This is a follow on to a previous post and discusses the interpretation of Newcomb’s Problem in more detail. If this topic doesn’t interest you, feel free to skip it and continue with the sequence.

When I talk about decision theory I am talking about normative rather than descriptive decision theory. Which is to say, I am looking at how decisions should be made not how they are made. Within normative decision theories though you can look at how decisions should be made in order for your choices to be rational or how they should be made in order to get the best outcome. Some people may argue that these are the same thing but many philosophers disagree including Richard Chappell who wrote a post that was at least partly a response to things that I’d said.

Richard introduced me to the notion of the difference between the disposition to act and the choice to act. In Newcomb’s Problem, you could distinguish between two boxing being the rational decision to make and one boxing being the rational disposition to develop within yourself. This is similar, though not necessarily identical, to my distinction between two questions in the sequence:

  1. Is the choice the one that leads to the best outcome and, hence, is it rational? (Choice)
  2. Is the decision theory the one that leads to the best outcome and, hence, is it rational? (Disposition)

So in Newcomb’s Problem, two boxing may be the rational choice but it may be rational to choose to follow a decision theory that suggests one boxing. In my post, I assumed without proof that the more important question was “Does the decision theory lead to the better outcome?” rather than “Does the choice lead to the better outcome?”

My perspective is that I want to find a decision theory that allows created or existing intelligent agents to gain the highest payoff so from my perspective the first of these questions is more important. However, if you are more interested in finding a decision theory that captures the idea of rationality then which question you should focus on seems less straightforward. However, nothing much seems to hang on the answer. If people disagree, it simply means they are talking about different topics rather than one being right and one being wrong.

That’s not to say there couldn’t be a more substantial form of disagreement. Two people could agree on the choice/disposition distinction and could agree on which of the two should be studied but still disagree as to what the rational choice is in Newcomb’s Problem. I’m currently maintaining an open mind on the particular question of which is the rational decision as I can see arguments for both sides.

In my own case though I find the debate interesting, it’s not of vital importance:  I’m looking for a decision theory that leads to the best outcomes, not one that leads to rationality.

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