Will_Sawin comments on Rationality Quotes: June 2011 - Less Wrong

4 Post author: Oscar_Cunningham 01 June 2011 08:17AM

You are viewing a comment permalink. View the original post to see all comments and the full post content.

Comments (470)

You are viewing a single comment's thread. Show more comments above.

Comment author: Eugine_Nier 23 June 2011 04:48:17AM 1 point [-]

Would you count Timeless Decision Theory as deontological since it isn't pure consequentialism?

Comment author: Will_Sawin 23 June 2011 02:16:23PM 1 point [-]

No, it's a decision theory, not an ethical theory.

Comment author: Eugine_Nier 24 June 2011 03:30:51AM 1 point [-]

I don't understand the distinction you're making.

Comment author: Will_Sawin 24 June 2011 03:32:48AM 1 point [-]

Decision theories tell you what options you have: Pairs of actions and results.

Ethical theories tells you which options are superior.

Comment author: Eugine_Nier 24 June 2011 04:11:34AM *  2 points [-]

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.

Comment author: Will_Sawin 24 June 2011 04:22:17AM 1 point [-]

It sounds deontological, but it isn't. It's consequentialist. It evaluates options according to their consequences.

Comment author: Eugine_Nier 24 June 2011 04:35:05AM 3 points [-]

"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.

Comment author: SilasBarta 24 June 2011 04:48:51PM 1 point [-]

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.)

Comment author: wedrifid 24 June 2011 05:32:43PM *  2 points [-]

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 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.

Comment author: benelliott 24 June 2011 03:32:41PM *  0 points [-]

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).

Comment author: Eugine_Nier 25 June 2011 03:48:15AM 1 point [-]

In both cases, while computing them you never assume anything which you know to be false

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.

Comment author: benelliott 25 June 2011 08:58:50AM 0 points [-]

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.

Comment author: Will_Sawin 25 June 2011 05:20:42AM 0 points [-]

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.

Comment author: Will_Sawin 24 June 2011 06:23:16PM 0 points [-]

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.

Comment author: benelliott 24 June 2011 09:10:09PM 0 points [-]

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).

Comment author: Will_Sawin 24 June 2011 04:46:04AM -1 points [-]

Yes. However that decision theory is wrong and dumb so we can ignore it. In particular, it never produces factuals, only counterfactuals.

Comment author: wedrifid 24 June 2011 03:51:15AM 1 point [-]

Decision theories tell you what options you have: Pairs of actions and results.

You don't need decision theories for that. You can get that far with physics and undirected imagination.

Comment author: Normal_Anomaly 24 June 2011 03:25:48PM 0 points [-]

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.

Comment author: Will_Sawin 24 June 2011 04:20:42AM 0 points [-]

That's only true if you're a human being.

Comment author: wedrifid 24 June 2011 05:42:35AM *  1 point [-]

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.

Comment author: Will_Sawin 24 June 2011 03:07:04PM 0 points [-]

"any possible mechanism of varying any element in your model of the universe".

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.

Comment author: wedrifid 24 June 2011 05:25:37PM *  0 points [-]

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.

Comment author: Will_Sawin 24 June 2011 06:20:54PM 0 points [-]

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?