Another way of viewing this would be that my preferences run thus: (D,C);(C,C);(C,D);(D,D) and Clippy run like this: (C,D);(C,C);(D,C);(D,D).

Wait, what? You prefer (C,D) to (D,D)? As in, you prefer the outcome in which you cooperate and Clippy defects to the one in which you both defect? That doesn't sound right.

It is a personal peeve when any explanation of the Bell Inequality fails to mention the determinist Big Loophole: It rules out nearly all local hidden-variable theories, except those for which the entire universe is ruled by hidden variables. If you reject the assumption of counterfactual definiteness (the idea that there is a meaningful answer to the question "what answer would I have gotten, had I conducted a different experiment?"), local hidden variable theories are not ruled out. This leads to superdeterminism and theories which assume that, through either hidden variables stretching back to t=0 or backwards-in-time signals, the universe accounted for the measurement and the result was determined to match.

This is, in fact, what I held to be the most likely total explanation for years, until I better understood both its implications and MWI. Which, in fact, also rejects counterfactual definiteness. MWI does it one better; it rejects factual definiteness, the idea that there is a well-defined answer to the question "What answer did I get?", since in alternate worlds you got different answers.

I agree it is better if both agents cooperate rather than both defect, and that it is rational to choose (C,C) over (D,D) if you can (as in the TDT example of an agent playing against itself). However, depending on how Clippy is built, you may not have that choice; the counter-factual may be (D,D) or (C,D) [win for Clippy].

I think "Clippy is a rational agent" is the phrase where the details lie. What type of rational agent, and what do you two know about each other? If you ever meet a powerful paperclip maximizer, say "he's a rational agent like me", and press C, how surprised would you be if it presses D?

I think what might be confusing is that your decision depends on what you know about the paperclip maximizer. When I imagine myself in this situation, I imagine wanting to say that I know "nothing". The trick is, if you want to go a step more formal than going with your gut, you have to say what your model of knowing "nothing" is here.

If you know (with high enough probability), for instance, that there is no constraint either causal or logical between your decision and Clippy's, and that you will not play an iterated game, and that there are no secondary effects, then I think D is indeed the correct choice.

If you know that you and Clippy are both well-modeled by instances of "rational agents of type X" who have a logical constraint between your decisions so that you will both decide the same thing (with high enough probability), then C is the correct choice. You might have strong reasons to think that almost all agents capable of paperclip maximizing at the level of Clippy fall into this group, so that you choose C.

(And more options than those two.)

The way I'd model knowing nothing in the scenario in my head would be something like the first option, so I'd choose D, but maybe there's other information you can get that suggests that Clippy will mirror you, so that you should choose C.

It does seem like implied folk-lore that "rational agents cooperate", and it certainly seems true for humans in most circumstances, or formally in some circumstances where you have knowledge about the other agent. But I don't think it should be true in principal that "optimization processes of high power will, with high probability, mirror decisions in the one-shot prisoner's dilemma"; I imagine you'd have to put a lot more conditions on it. I'd be very interested to know otherwise.

It's from the most common spoken order. "March fourteenth, twenty-fifteen."

I am starting to think that Lord Voldemort planned to commit suicide by proxy. Being without any personal aims, totally bored, without any happiness, surrounded by idiots, no chance of improvement - yet he cares about the world, at least somewhat, and realized that the original plan of playing chess with Harry would not alleviate his mood anymore anyway. And he has a better, happier and (age adjusted) more intelligent clone running around, so it is not like he will cease to exist altogether.

So he told Harry where to find Memory charms, prepared the plot, got the Stone (for Harry), made Harry take the Vow to keep his recklessness in limits, let him keep his wand and put him to the Final Exam.

The problem is that if he planned to be Obliviated, the plot was extremely complicated and relied on too many factors that could have gone wrong. So perhaps LV just threw the towel and said to himself, darn, let's Harry try whatever he can think about to do with us, and if he fails, well, it's not like I cannot try something else in some decades.

"Other living weapons cannot be Transfigured; they will not survive the disenchantment for the requisite six hours to avoid being traced by Time-Turner."

So, how does Harry plan to evade been traced by Time-Turner?

Is it correct that Voldemort will die when he will be disenchanted?

By the way, why did Voldemort make a description of Hermione resurrection ritual and put it in a pouch if he planed to kill Harry anyway?

Well, that's certainly one way to explain away all of the strange aspects. Establish them as fact, through the mysterious bond between LV and HP, and do so in front of a huge crowd so that the word can spread and mutate on its own. By the time anyone comes to investigate or question, they will already be influenced by the show or rumors they've heard, promoting that hypothesis to their attention rather than coming to it naturally.

It's pointing the police at Mortimer Snodgrass, from chapter 17, as it were.

So... what we should do now is to work out all the things Quirrell should have before this. He couldn't predict partial transfiguration, true. But he knew that Harry had a power he knew not, and had a long time to plan for contingencies.

Personally, I think he should have had the death eaters disillusioned, surround Harry but from a distance, cast holograms to confuse him and then use ventriliquo charms. At the very least disillusionment should be as much of a general tactic as a massed finite and the death eaters could have been hidden.

The massively more obvious solution is just to kill Harry quickly, and moreover to not EVER offer the protagonist 60 seconds to try to save himself, no matter how interesting that sounds.

Any other general/specific tactics that LV could and should have thought of in advance? He had an entire year to plan this, and has Harry level intelligence. He should have predicted and outplayed.