Seconded. This is an extremely impressive paper. It seems like Spohn had most of the insights that motivated and led to the development of logical/functional decision theories, years before Less Wrong existed. I’m astounded that I’ve never heard of him before now.
I don’t think Eliezer had encountered this mainstream work when he wrote his articles
Eliezer’s TDT decision algorithm (2009, 2010) had been previously discovered as a variant of CDT by Wolfgang Spohn (2003, 2005, 2012). Both TDT and Spohn-CDT (a) use Pearl’s causal graphs to describe Newcomblike problems, then add nodes to those graphs to represent the deterministic decision process the agent goes through (Spohn calls them “intention nodes,” Yudkowsky calls them “logical nodes”), (b) represent interventions at these nodes by severing (edit: or screening off) the causal connections upstream, and (c) propose to maximize expected utility by summing over possible values of the decision node (or “intention node” / “logical node”). (Beyond this, of course, there are major differences in the motivations behind and further development of Spohn-CDT and TDT.)
Finally, a post from a few months ago also mentions Spohn:
I introduce dependency equilibria (Spohn 2007), an equilibrium concept suitable for ECL, and generalize a folk theorem showing that the Nash bargaining solution is a dependency equilibrium.
In looking through Spohn’s oeuvre, here are a couple of papers that I think will be of interest on LessWrong, although I have not read past the very beginnings.
“Dependency Equilibria” (2007). “Its philosophical motive is to rationalize cooperation in the one shot prisoners’ dilemma.”
And since 2020, he leads this project on Reflexive Decision & Game Theory (longer outline). The site doesn’t list any results of this project, but presumably some of Spohn’s papers since 2020 are related to this topic.
The Koselleck project explores reflexive decision and game theory. Standard decision and game theory distinguish only chance nodes (moves by nature) and action nodes (possible actions of the agent or player, usually and confusingly called decision nodes). The reflexive extensions additionally distinguish genuine decision nodes referring to possible decision situations (decision or game trees plus probability and utility functions) the agent may be in or come to be in. Thus, these decision nodes generate a rich recursive structure. This structure is required, though. Surely, we agents not only rationally act within a given decision situation, but are also able to reflect on the possible situations which might be ours and thus about what determines or causes our actions. And clearly, such reflection is important for rational decision making.
The reflexive extension allows for a general account of anticipatory rationality, i.e., of how to rationally behave in view of arbitrary envisaged changes in one’s decision situation (so far incomepletely treated under the labels “strategic rationality” and “endogenous preference change”). The extension also allows us to account for what is called sensitive rationality, which considers a so far largely neglected point, namely the fact that being in a certain situation not only causes the pertinent rational action, but may have side effects as well (as exemplified in the Toxin puzzle). This fact is ubiquitous in social settings, and it is highly decision relevant and can obviously be accounted for only in the reflexive perspective. Moreover, the extension also allows us to respect the point that it is a matter of our decision when to decide about a certain issue, e.g., whether to commit early or to decide as late as possible. This leads to an account of so-called commissive rationality possiblyrationalizing our inclination to commit ourselves. Finally, in the game theoretic extension suggested by the phenomenon of sensitive rationality, the reflexive perspective leads to a new equilibrium concept called dependency equilibria, which, e.g., allows a rationalization of cooperation in the one-shot prisoners’ dilemma and promises a kind of unification of noncooperative and cooperative game theory.
This should say 2007.
Spohn argues for one-boxing in Reversing 30 years of discussion: why causal decision theorists should one-box.
Fixed.
Thanks for the reference. I hope this doesn’t turn out to be a case of changing CDT and calling the result CDT.
ETA: 8 pages in, I’m impressed by the clarity, and it looks like it leads to something reasonably classified as a CDT.
Seconded. This is an extremely impressive paper. It seems like Spohn had most of the insights that motivated and led to the development of logical/functional decision theories, years before Less Wrong existed. I’m astounded that I’ve never heard of him before now.
Having searched for “Spohn” on LW, it appears that Spohn was already mentioned a few times on LW. In particular:
11 years ago, in lukeprog’s post Eliezer’s Sequences and Mainstream Academia (also see bits of this Wei Dai comment here, and of this long critical comment thread here):
And the comments here on the MIRI paper “Cheating Death in Damascus” briefly mention Spohn.
Finally, a post from a few months ago also mentions Spohn:
It probably doesn’t help that he’s a German philosopher; language barriers are a thing.
On the other hand, his research interests seem to have lots of overlap with LW content:
In looking through Spohn’s oeuvre, here are a couple of papers that I think will be of interest on LessWrong, although I have not read past the very beginnings.
“Dependency Equilibria” (2007). “Its philosophical motive is to rationalize cooperation in the one shot prisoners’ dilemma.”
“The Epistemology and Auto-Epistemology of Temporal Self-Location and Forgetfulness” (2017). It relates to the Sleeping Beauty problem.
More stuff:
He co-initiated the framework program “New Frameworks of Rationality” (German Wikipedia, German-only website) which seems to have been active in 2012~2018. Their lists of publications and conferences are in English, as are most of the books in this list.
(Incidentally, there’s apparently a book called Von Rang und Namen: Philosophical Essays in Honour of Wolfgang Spohn.)
And since 2020, he leads this project on Reflexive Decision & Game Theory (longer outline). The site doesn’t list any results of this project, but presumably some of Spohn’s papers since 2020 are related to this topic.