Introduction

Decision theory is about how to behave rationally under conditions of uncertainty, especially if this uncertainty involves being acausally blackmailed and/or gaslit by alien superintelligent basilisks.

Decision theory has found numerous practical applications, including proving the existence of God and generating endless LessWrong comments since the beginning of time.

However, despite the apparent simplicity of "just choose the best action", no comprehensive decision theory that resolves all decision theory dilemmas has yet been formalized. This paper at long last resolves this dilemma, by introducing a new decision theory: VDT.

Decision theory problems and existing theories

Some common existing decision theories are:

Causal Decision Theory (CDT): select the action that *causes* the best outcome.
Evidential Decision Theory (EDT): select the action that you would be happiest to learn that you had taken.
Functional Decision Theory (FDT): select the action output by the function such that if you take [...]

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Outline:

(00:53) Decision theory problems and existing theories

(05:37) Defining VDT

(06:34) Experimental results

(07:48) Conclusion

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First published:
April 1st, 2025

Source:
https://www.lesswrong.com/posts/LcjuHNxubQqCry9tT/vdt-a-solution-to-decision-theory

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Narrated by TYPE III AUDIO.

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Images from the article:

Table 1: Decades of rationality and no solution found, have they have played us for fools?

Table 2: <span>Look on my works, ye Mighty, and despair!</span>

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“VDT: a solution to decision theory” by L Rudolf L

LessWrong (30+ Karma)