I am currently learning about the basics of decision theory, most of which is common knowledge on LW. I have a question, related to why EDT is said not to work.
Consider the following Newcomblike problem: A study shows that most people who two-box in Newcomblike problems as the following have a certain gene (and one-boxers don't have the gene). Now, Omega could put you into something like Newcomb's original problem, but instead of having run a simulation of you, Omega has only looked at your DNA: If you don't have the "two-boxing gene", Omega puts $1M into box B, otherwise box B is empty. And there is $1K in box A, as usual. Would you one-box (take only box B) or two-box (take box A and B)? Here's a causal diagram for the problem:
Since Omega does not do much other than translating your genes into money under a box, it does not seem to hurt to leave it out:
I presume that most LWers would one-box. (And as I understand it, not only CDT but also TDT would two-box, am I wrong?)
Now, how does this problem differ from the smoking lesion or Yudkowsky's (2010, p.67) chewing gum problem? Chewing Gum (or smoking) seems to be like taking box A to get at least/additional $1K, the two-boxing gene is like the CGTA gene, the illness itself (the abscess or lung cancer) is like not having $1M in box B. Here's another causal diagram, this time for the chewing gum problem:
As far as I can tell, the difference between the two problems is some additional, unstated intuition in the classic medical Newcomb problems. Maybe, the additional assumption is that the actual evidence lies in the "tickle", or that knowing and thinking about the study results causes some complications. In EDT terms: The intuition is that neither smoking nor chewing gum gives the agent additional information.
I think UDT reasoning would go like this (if translated to human terms). There are two types of mathematical multiverse, only one of which is real (i.e., logically consistent). You as a UDT agent gets to choose which one. In the first one, UDT agents one-box in this Genetic Newcomb Problem (GNP), so the only genes that statistically correlate with two-boxing are those that create certain kinds of compulsions overriding deliberate decision making, or for other decision procedures that are not logically correlated with UDT. In the second type of mathematical multiverse, UDT agents two-box in GNP, so the list of genes that correlate with two-boxing also includes genes for UDT.
Which type of multiverse is better? It depends on how Omega chooses which gene to look at, which is not specified in the OP. To match the Medical Newcomb Problem as closely as possible, let's assume that in each world (e.g., Everett branch) of each multiverse, Omega picks a random gene look at (from a list of all human genes), and puts $1M in box B for you if you don't have that gene. You live in a world where Omega happened to pick a gene that correlates with two-boxing. Under this assumption, the second type of multiverse is better because the number and distribution of boxes containing $1M is exactly the same in both multiverses, but in the second type of multiverse UDT agents get the additional $1K.
I think the reason we have an intuition that we should one-box in the GNP is that when we first read the story, we implicitly assume something else about what Omega is doing. For example, suppose instead of the above, in each world Omega looks at the most common gene correlated with two-boxing and puts $1M in box B if you don't have that gene. If the gene for UDT is the most common such gene in the second multiverse (where UDT two-boxes), then the first multiverse is better because it has more boxes containing $1M, and UDT agents specifically all get $1M instead of $1K.
Thank you for this elaborate response!!
Why would Omega look at other human genes and not the two-boxing (correlated) gene(s) in any world?
Maybe I overlook something or did not describe the probl... (read more)