We don’t normally say that two objects must be causally linked just because they are qualitatively identical. Why should brains be different?
What’s scariest about the infinite universe idea, with infinite duplicates of ourselves occurring within various minimum distances is…
It assails reason. It produces the “library of Babel.” There’s another copy of “you” out there. Then there’s a copy of “you” identical except for the trivial difference of eye color. And then there’s the “gay” you, and the “straight” you, and the “liberal” you and the “conservative” you, and the you who went on to be a football player, and the you who rose to become dictator of Peru, and…
The idea produces every possible result, including the absurd ones. In doing so, it demolishes (or at least challenges) reason. There’s the world, identical to earth in nearly all ways, where all the air molecules in your room just whooshed over to one corner, leaving you in a vacuum…
Harvard Lampoon once said, “If Karl Marx had been a goat, Das Kapital would have been written entirely without vowels.” In an infinite universe, this actually has to have happened, and not only once, but an infinite number of times.
The universe just might be that absurd! But it seems like a really, really rotten basis for philosophical reasoning. We’re privileged enough to live in a small, isolated pocket, where “reason” works, and the absurd is limited to football finals and celebrity marriages.
This is true, but complexity comes into the equation in a big way. If two complex objects are identical, this must be either the result of a causal linkage or a remarkable coincidence.
Perhaps the most useful thing the ‘infinite universe’ thought experiment does is point out just how unlikely the spontaneous emergence elsewhere of an identical human mind would be.
For the sake of completeness, there are other possibilities than just those two: it could be an emergent phenomenon from simple laws. Or the result of intelligent entities trying to solve the same kind of problem.
I’m not saying this is the case with brains, we talking abstractly now about the reasoning.
In fact (I should open a new thread) I’m gonna call B.S. on the “identical mind” even in an infinite universe… Because…
A human mind is the product of its environment. No Roman Empire? No Romance Languages, no “French” nationality, no French Revolution, no possibility of any human mind on that version of earth being the “same” as any mind on our earth.
Geography: for minds to be the same, the geography would have to be identical. Japan and Britain as islands, Panama as an isthmus, Arabian oil, Californian gold, etc.
The stars in the night sky! There would have to be a “North Star.” There would have to be a “Big Dipper,” and the Pleiades, and the supernova of 1987, and… If any one of these was different, then our minds would be different.
For a human mind to be duplicated to the level of absolute identity, the whole effin’ cosmos would have to be duplicated. The distance factor between replicated regions of space would have to be increased by absurd levels of exponentiation!
Relatively similar minds? Sure. No prob. There are probably “thinking people” in our observable region of space, some of whom might even be addressing these same issues at this moment. I feel a sense of “sameness” with them, but only in the sense that I feel a sense of “sameness” with several of the people who have posted in this thread.
But down-to-the-last-atom identical? Pfaw. “Show me.”
And even if these hypothetical alternative realities exist, you as an individual consciousness are experiencing only one of them. That supports the notion that just because there is a physical being out there that is identical to you in detail, it’s still not you.
That’s not quite true. For example there is a non-zero chance of a bunch of organic molecules happening to fall together to make a brain identical to yours. In an infinite universe the ridiculous unlikeliness of this is not significant.
Or, say, a different environment might mold a brain different to yours. But then this brain experiences brain damage that just by chance now makes it identical to yours. e.g. it would have false memories of once reading the straight dope.
Irrelevant. We’re talking infinity here. You can say every version of you is Graham’s number light years apart. No problem.
disclaimer
It should be noted that technically infinity does not guarantee that anything possible will happen (an infinite number of times). If you imagine the infinite monkeys and infinite typewriters, what law of physics would it break if they were to just press the space bar an infinite number of times, and never touch the letters? None.
The inevitability of identical minds is a practical truth (in an infinite universe), we can have confidence it’s true, but it’s not formally true.
Bingo
Give me the choice between only one of the following surviving for my own selfish interest: an exact copy of me down to the last quantum string created somewhere…over there, or the person in my original body after being frontal lobotomized, I’ll play it safe, embrace the name Scarface and hope the surgeon didn’t ablate my fondness for women. Betting on having a future in another brain is tantamount to believing selling Amway will make you rich.
To quote Monty Python, “My brain hurts!” You’re certainly right!
A mathematician once told me that an infinite universe might be “fractal” in some fashion, so that reality “clumps together” in such a way as to prevent some possibilities from being realized. Your example of the monkeys spending all their time hitting the space bar is (I think) a similar kind of reasoning.
Heck, given an infinite universe, without the kinds of exemptions that Mijin just mentioned, some of those infinite copies of your brain/mind will know that they are copies/duplicates/survivors/relicts of you! Just as Mijin pointed out that a distant brain could be damaged to become exactly like mine, it could also be damaged to produce “false memories” that allow it to know that another “you” or another “me” once existed in a distant place, and that it carries those memories forward!
If you make an Amway pitch to an infinite number of people…
Just how identical do two brains have to be in order for them to have the same consciousness, in this scenario? Obviously they don’t have to be exactly identical, right? I mean, compare the software of your brain at age 5 to that of your brain at age 75. For effect, let’s even include a few incidences of minor head trauma and a couple of TIA’s along that brains timeline. Arguably the software of your 5 year old brain is significantly different from that of your 75 year old brain, and yet most will agree that they share the same consciousness, simply separated by time and development.
Now compare the software of your brain at age 20 to that of your identical twin at age 20 who has been hand-cuffed to your wrist from birth and tends to look where you look and parrot what you say. Arguably the software of those two brains is more similar than that of your 5 year old brain to your 75 year old brain, and yet most will agree that you and your twin have, and always have had, separate consciousnesses.
So, is it similarity of the software that accounts for whether or not consciousnesses are the same or different, or is it the relationship of the software to the hardware? I argue that it is the relationship of the software to the hardware that makes consciousness singular and continuous. Software (your consciousness) that has been in continuous contact with an overwhelmingly unchanging physical structure (your CNS) is different than one that has not. That alone can account for every consciousness in the universe being unique.
Souls are mystical things the properties of which are unknown and possibly unknowable. It seems like a soul could be shared between two people, especially if those people are identical copies. Or equally, maybe it couldn’t be. Maybe duplicating the person duplicates the soul automatically. Some beliefs about souls hold them to be a mass noun (soulstuff is dividable, returns to a pool etc) and some beliefs hold them to be multipartite (ka and ba, etc).
Self is an illusion product of consciousness (or maybe they are synonymous) - so it’s reasonable that some conscious entities would feel their duplicate was the same self, and others would feel it was not. It’s subjective in the first place so they’re both right, for themselves, and there’s no objective factors really to establish one over the other.
“Is that really me?” Similar, I think, to asking whether you really love someone. The answer comes from introspection and emotion.
I was once at a party and thought that the person I was talking to was me. It was all quite Zen-like and enlightening until I learned that the hand-rolled cigarette I was smoking was laced with angel dust. (It was the ‘70’s…stuff like that happened).