Quantum Wildlife

David Wallace wrote an article about reductionism, emergence, and worlds in the many worlds interpretation of quantum mechanics that’s enlightening and more accessible than his earlier writings:

Decoherence and Ontology (or: How I learned to stop worrying and love FAPP)

Ultimately, though, that a theory of the world is “unintuitive” is no argument
against it, provided it can be cleanly described in mathematical language. Our
intuitions about what is “reasonable” or “imaginable” were designed to aid our
ancestors on the savannahs of Africa, and the Universe is not obliged to conform
to them.

I especially enjoyed figure 2 and footnote 14.

Wallace also has a latest update on the program to derive Born probabilities from decision theory:

A formal proof of the Born rule from decision-theoretic assumptions

I tend to think of Wallace’s as the most orthodox interpretation of quantum mechanics, it’s just that people don’t know it yet.

Quantum Immortality: First Salvo

Jacques Mallah has put a paper on the ArXiv arguing against the theory of “quantum immortality” (which says that as long as there remains at least one quantum world with a copy of you in it, you should expect to stay alive) and the related idea of “quantum suicide” (which says that, since you’re “quantum immortal” anyway, you might as well correlate your death with things like not winning the lottery). I’m not yet sure I’d endorse the whole paper, but like Mallah, I believe in the many-worlds interpretation of quantum mechanics, and like Mallah, I do not believe that it implies quantum immortality. I promised long ago to write a post against the idea, but I didn’t get around to it, so I’ll take this opportunity to expand on something Mallah says and sort of get things started:

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On one conception,

  • “morality” is about doing what is right according to some moral system that you agree with
  • “ethics” is a set of constraints on actions, applying even if those actions seem to be moral

I’d say ethics tells us that where possible, we should make our actions compatible with a wide variety of moralities that one could reasonably hold, as well as a wide variety of moralities that people actually hold.

There are at least two reasons for this:

  1. Those moralities that people could reasonably hold, might actually be correct.
  2. Not going against those moralities that people do hold, and cultivating the disposition not to do so, amounts to cooperating in a repeated prisoner’s dilemma.

“Ethics” is also the name of the subfield of philosophy that studies this sort of thing, but there’s no reason to let that confuse us.

An Anti-Pascalian Intuition

Let X be something important, like going to heaven. Let Y be something less important, like one day’s worth of peace of mind.

Intuition: for all sufficiently high levels of utility U, the probability that for some reason Y has at least U importance is at least 1/10^30 times the probability that X has at least U importance.

This is iffy in several different ways, but the iffinesses in the solution might be the same iffinesses in the problem.

(What do these absolute utility levels even mean? Probably nothing, but on the other hand it seems you need something like them if you want to do anything like maximize expected utility over different ethical systems.)

All Are One, But Not Really

Julian Baggini asks whether an iPod is part of your mind, in the context of Extended Mind thinking in philosophy.

I doubt such questions need an unambiguous answer. Is my upper neck part of my head? Is a tree part of planet Earth? Is Gibraltar part of Great Britain? Meh.

In a way, the hippies are right: you can see the universe as one big mind. But it’s made of billions of unconnected pieces. The world has a case of Massively Parallel Multiple Personality Disorder.

This is more than just a joke. If two minds each experiencing one thing are really the same as one mind experiencing two independent things, this could serve as a useful constraint on answers to various vexing conundrums in philosophical ethics and decision theory.


In an earlier post I distinguished between strong and weak immortalism, where the former says one long life is better than many short lives and the latter merely says one long life is better than one short life.

A population ethics paper called “Life Extension versus Replacement” by Gustaf Arrhenius considers and rejects two bad arguments for the strong-immortalist position (three bad arguments if you count “average utilitarianism”). All of these bad arguments modify “standard” total-utilitarian population ethics.

I think there are some better arguments for strong immortalism within standard utilitarianism. Maybe:

  1. …having a greater amount of existing structure to build on (memories and the like) allows for more valuable future experiences
  2. …old minds are living monuments that make the lives of others more interesting, like the seven wonders of the world
  3. …leading a more or less unique life is a part of welfare, and 100-year lives will repeat to an extent because there are so many more of them
  4. …any mind gets “tangled up” with others and with its own preferences, so that its destruction creates anti-valuable grief and thwarted aspirations
  5. …older minds attain more virtue and competence so they are more extrinsically useful

Arguments could go the other way, too. Maybe there’s a limited number of especially valuable life events you can experience — this question is related to what Eliezer Yudkowsky calls fun theory.

But even if those arguments are stronger than the ones I listed, that may not mean we shouldn’t research life extension in practice. Here are a few reasons:

  1. Option value. If living is a mistake you can still die later, if dying is a mistake you can’t come back.
  2. We aren’t actually at Earth’s population limits, so it’s not the case that by living for 1000 years you deny ten other potential people a 100-year life. Arguing for life extension currently requires only what I called “weak immortalism”, not “strong immortalism”.
  3. None of the arguments for death (other than bad ones, like “nature knows best”) would seem to single out 100 years as the right lifespan.
  4. None of the arguments for death would seem to argue for the complete destruction of minds, rather than for starting over only partially.

In sum, I would be shocked if a complete understanding of population ethics caused us to favor unextended human lives into the indefinite future.

The Calculus of Doubt

From the conclusion of “Disbelief as the Dual of Belief” by John Norton:

The natural presumption is that degrees of belief are primary and that degrees of disbelief and their associated logic are parasitic upon them. Nothing within the logic of belief and disbelief supports this presumption. We have seen that the duality of belief and disbelief supports a complete isomorphism of the two. For every axiom, property, proof or theorem of the one, there is an analog in the other. Therefore, for any reason, argument or principle we may find within the logic of belief as supporting its primacy, there will be an exactly matching dual reason, argument or principle within the logic of disbelief supporting the latter. If the primacy of belief over disbelief is more than an accident of our history, the reason must be sought outside the logics of belief and disbelief.

I wonder if thinking in terms of disbeliefs (and disprobabilities?) could reverse some common cognitive biases.

What Relativity Doesn’t Teach Us

In this pdf article John D. Norton investigates a long list of philosophical morals that have been drawn from relativity theory and finds most of them wanting — not true, not new, or based on either something more or something less than general relativity.

That could mean relativity isn’t as weird (to us) as we thought, or it could mean the old physics was weirder than we thought. Probably a bit of both.

Contrary to a recent commenter on Overcoming Bias (I forget who, maybe Eliezer), I think philosophers of physics tend to do better philosophy of physics than physicists, for an unmysterious reason: it’s their specialty.