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Will_Sawin comments on Rationality Quotes: June 2011 - Less Wrong
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No, it's a decision theory, not an ethical theory.
I don't understand the distinction you're making.
Decision theories tell you what options you have: Pairs of actions and results.
Ethical theories tells you which options are superior.
Perhaps an example of what I mean will be helpful.
Suppose your friend is kidnapped and being held for ransom. Naive consequentialism says you should pay because you value his life more then the money. TDT says you shouldn't pay because paying counterfactually causes him to be kidnapped.
Note how in the scenario the TDT argument sounds very deontological.
It sounds deontological, but it isn't. It's consequentialist. It evaluates options according to their consequences.
"Consequences" only in a counterfactual world. I don't see how you can call this consequentialist without streching the term to the point that it could include nearly any morality system. In particular by your definition Kant's categorical imperative is consequentialist since it involves looking at the consequences of your actions in the hypothetical world where everyone performs them.
Yes, in that TDT-like decision/ethical theories are basically "consequentialism in which you must consider 'acausal consequences'".
While it may seem strange to regard ethical theories that apply Kant's CI as "consequentialist", it's even stranger to call them deontological, because there is no deontic-like "rule set" they can be said to following; it's all simple maximization, albeit with a different definition of what you count as a benefit. TDT, for example, considers not only what your action causes (in the technical sense of future results), but the implications of the decision theory you instantiate having a particular output.
(I know there are a lot of comments I need to reply to, I will get to them, be patient.)
It certainly is strange even if it is trivially possible. Any 'consequentialist' system can be implemented in a singleton deontological 'rule set'. In fact, that's the primary redeeming feature of deontology. Kind of like the best thing about Java is that you can use it to implement JRuby and bypass all of Java's petty restrictions and short sighted rigidly enforced norms.
Both CDT and TDT compare counter-factuals, they just take their counter-factual from different points in the causal graph.
In both cases, while computing them you never assume anything which you know to be false, whereas Kant is not like that. (Just realised, I'm not sure this is right).
Counterfactual mugging and the ransom problem I mentioned in the great-grandparent are both cases where TDT requires you to consider consequences of counterfactuals you know didn't happen. Omega's coin didn't come up heads, and your friend has been kidnapped. Nevertheless you need to consider the consequences of your policy in those counterfactual situations.
I think counterfactual mugging was originally brought up in the context of problems which TDT doesn't solve, that is it gives the obvious but non-optimal answer. The reason is that regardless of my counterfactual decision Omega still flips the same outcome and still doesn't pay.
There are two rather different things both going under the name counterfactuals.
One is when I think of what the world would be like if I did something that I'm not going to do.
Another is when I think of what the world would be like if something not under my control had happened differently, and how my actions affect that.
They're almost orthogonal, so I question the utility of using the same word.
Well, I've been consistently using the word "conterfactual" in your second sense.
You need a proof-system to ensure that you never assume anything which you know to be false.
ADT and some related theories have achieved this. I don't think TDT has.
What I meant by that statement was the idea that CDT works by basing counterfactuals on your action, which seems a reasonable basis for counterfactuals since prior to making your decision you obviously don't know what your action will be. TDT similarly works by basing counterfactuals on your decision, which you also don't know prior to making it.
Kant, on the other hand, bases his counter-factuals on what would happen if everyone did that, and it is possible that his will involve assuming things I know to be false in a sense that CDT and TDT don't (e.g. when deciding whether to lie I evaluate possible worlds in which everyone lies and in which everyone tells the truth, both of which I know not to be the case).
Well here is the issue.
Let's say I have to decide what to do at 2'o'clock tomorrow. If I light a stick of dynamite, I will be exploded. If I don't, then I won't. I can predict that I will, in fact, not light a stick of dynamite tomorrow. I will then know that one of my counterfactuals is true and one is false.
This can mess up the logic of decision-making. There are . This ensures that you can never figure out a decision before making it, which makes things simpler.
I'm not sure if this contradicts what you've said.
And I would agree exactly with your analysis about what's wrong with Kant, and how that's different from CDT and TDT.
Yes. However that decision theory is wrong and dumb so we can ignore it. In particular, it never produces factuals, only counterfactuals.
You don't need decision theories for that. You can get that far with physics and undirected imagination.
How about this:
Physics tells you pairs of actions and results.
Ethical theories tell you what results to aim for.
Decision theories combine the two.
That's only true if you're a human being.
That is not my understanding. The only necessary addition to physics is "any possible mechanism of varying any element in your model of the universe". ie. You need physics and a tiny amount of closely related mathematics. That will give you a function that gives you every possible action -> result pair.
I believe this only serves to strengthen your main point about the possibility of separating epistemic investigation from ethics entirely.
That's a decision theory. For instance, if you perform causal surgery, that's CDT. If you change all computationally identical elements, that's TDT. And so on.
I don't agree. A decision theory will sometimes require the production of action result pairs, as is the case with CDT, TDT and any other the decision algorithm with a consequentialist component. Yet not all production of such pairs is a 'decision theory'. A full mathematical model of every possible state to the outcomes produced is not a decision theory in any meaningful sense. It is just a solid understanding of all of physics.
On one hand we have (physics + the ability to consider counterfactuals) and on the other we have systems for choosing specific counterfactuals to consider and compare.
If you don't have a system to choose specific counterfactuals, that leaves you with all counterfactuals, that is, all world-histories, theoretically possible and not. How do you use that list to make decisions?
That is my point. That is what the decision theory is for!