If you're contemplating picking the book up, do, it's really excellent. Conceptually very dense but worth taking it nice and slowly.

Sounds like putting a name on 'the stuff we don't fully understand yet' - not helpful.

Helpful. We need to put labels on Stuff We Don't Understand yet so that we know what we are talking about when we try t understand it.

Fixed - sorry!

Update: have now made a MOBI for the Kindle too.

EDIT: fixed - thanks!

Apologies for coming to this party a bit late. Particularly as I find my own answer really, really frustrating. While I wouldn't say it was an origin per se, getting into reading Overcoming Bias daily a few years back was what crystallised it for me. I'd find myself constantly somewhere between "well, yeah, of course" and "ohhhhhhhhhhhhhhh!" Guess the human brain doesn't tend to do Damascene revelations. We need overwhelming evidence, over a long period of time, to even begin chipping away at our craziest beliefs, and even then it's a step-by-step process.

The analogy I sometimes go over is something most people find fairly obvious like egalitarianism. You don't find many people who would attest to being pro-inequality. But all the same, you find very few people who have genuinely thought through what it means to be in favour of equality and really try to fit that into everyday life. The first step to becoming a rationalist is to admit how irrational everyone is without monumental efforts to the contrary.

BTW, I am totally on the road to de-Catholicising my mother. This is on the order of converting Dubya to Islam, so if I can manage that I'm awarding myself an honorary brown belt.

I think the response is: that MWI isn't "Infinite plot-threads of fate" - or narrativium as it's put in the Discworld novels - quantum decay doesn't give a whit of care whether it's effects are noteworthy for us or not.

On the two 'far ends' of the spectrum, I'd expect to see significant plot-decay - particle causes Hitler to get cancer, he dies halfway through WWII - but I have trouble imagining a situation where a quantum event which will make the difference between my motorcycle sticking to the curve, and the tire skidding out, leaving my fragile body to skid across the pavement at 120 km/h, leaving a greasy trail that skids-out the semi riding behind me.

Quantum-grenades are one of the few exceptions, where small-world events affect us here in the middle-world. But I wouldn't count on MWI to produce a perfect bank robbery.

The people who want to become AIs in order to take over the world and bend it to their own sinister, narrow ends will try to convince people that everyone else's AIs are dangerous and must be destroyed.

(B) if he thanks you for the free $100, does he ask for another one of those nice free hundred dollar note dispensers? (This is the "quantum suicide" option

I laugh in the face of anyone who attests to this and doesn't commit armed robbery on a regular basis. If 'at least one of my branches will survive' is your argument, why not go skydiving without a parachute? You'll survive - by definition!

So many of these comments betray people still unable to think of subjective experience as anything other than a ghostly presence sitting outside the quantum world. 'Well if this happens in the world, what would I experience?' If you shoot yourself in the head, you will experience having your brains blown out. The fact that contemplating oneself's annihilation is very difficult is not an excuse for muddling up physics.

The phrase "for me to be an animal" may sound nonsensical, but "why am I me, rather than an animal?" is not obviously sillier than "why am I me, rather than a person from the far future?".

Agreed - they are both equally silly. The only answer I can think of is 'How do you know you are not?" If you had, in fact, been turned into an animal, and an animal into you, what differences would you expect to see in the world?

What if I hack & remove $100 from your bank account. Are you just as wealthy as you were before, because you haven't looked? If the 2 copies simply haven't looked or otherwise are still unaware, that doesn't mean they are the same. Their possible futures diverge.

And, sure, it's possible they might never realize - we could merge them back before they notice, just as I could restore the money before the next time you checked, but I think we would agree that I still committed a crime (theft) with your money; why couldn't we feel that there was a crime (murder) in the merging?