[skissane]

I think Bostrom’s core argument is likely valid - the more ancestor simulations you run, the greater the odds you are actually in one yourself. Now, right now that number is zero, and we don’t know if it will ever rise above zero, and even if one day it does, that day is likely many centuries away. But maybe in 500 or 5000 years time, ancestor simulations will be very numerous, and Bostrom’s argument may convince many people in such a scenario

Unfalsifiable propositions can be true, and it is even possible to have good reason-whether direct or indirect evidence-for believing one

“Somewhere and somewhen in this universe there exists an extremely controversial and very famous politician named Donald Trump” is an example of a proposition which is true, and we have very good reason to believe is true, but which is strictly speaking unfalsifiable, indeed almost inherently so. Even if we suppose our Donald Trump had never been born, we could not rule out the possibility of some very famous and controversial politician having that name (let’s say named by a very similar sequence of sounds) existing on a planet in a distant galaxy. If one accepts a B theory view of time, that proposition has always been true, and was just as true in 5000 BCE as it is today, but nobody back then could have possibly known it was true.

[vidarh]

Exactly.

But it is worth also remembering that Bostroms Simulation Argument is an argument for simulation, not the only one possible.

To me the original point I made was simply that non-determinism can't falsify simulation.

More broadly I believe simulation is unfalsifiable, because the impossibility of proving we have existence in time (our consciousness could exist for only a moment, and we can't tell, because we have access to the past only as memories which could be fake), or that a world outside ourselves exists (our sensory inputs could be fake) means we can say hardly anything about the scale or complexity of a theoretical simulation. Said another way: we don't know even how much of ourselves exists.

That opens the door to a vast set of possible simulation arguments, but also raises the question of whether there is a clear line between simulation and what reality is. E.g. you can imagine a similar set of possible conceptions of a physical reality. If physical reality is that our existence is mere fragmentary moments of parts of a mind, then that would mean any experience we might think we have one day of building simulations would themselves be illusory.

So it's not a given that we can meaningfully tell whether or not a simulation exists even if we one day believe we successfully build one, because the experience of building the simulation might well be the totality of the experience. There's no certainty said simulation ever exists.

Trying to nail down what we can actually infer about this is something we'll struggle with for a very long time.

Even defining in concrete terms what is simulation vs. simply an arrangement of physical reality is unclear (think Hitchhikers Guide to the Galaxy where Earth was a computer)

[skissane]

> because the impossibility of proving we have existence in time (our consciousness could exist for only a moment, and we can't tell, because we have access to the past only as memories which could be fake), or that a world outside ourselves exists (our sensory inputs could be fake) means we can say hardly anything about the scale or complexity of a theoretical simulation. Said another way: we don't know even how much of ourselves exists.

Consider the following argument:

1] If P being true is a necessary precondition for rational thought to exist, we are rationally justified in believing that P is true

2] The general reliability of our memories is a necessary precondition for rational thought to exist

3] Therefore, we are rationally justified in believing that our memories are generally reliable

4] Therefore, our memories are generally reliable

From the general reliability of our memories, the substantial existence of the past trivially follows; does that count as "proving we have existence in time"? And replace the "general reliability of our memories" with "the existence of other minds" to turn the above argument into a proof of the later.

> but also raises the question of whether there is a clear line between simulation and what reality is.

I actually think the simulation hypothesis is a pretty good argument for idealism: if the simulation hypothesis is true, then either materialism is simply false (if one interprets "matter" to mean only the apparent physical matter of this universe), or else its truth is unknowable (if one interprets "matter" to mean the unknowable matter of the substrate universe.) If we cannot know whether the simulation hypothesis is true, how can we know that materialism is true? By contrast, if idealism is true, then minds and their experiences are the most fundamental constituents of reality; whether this universe is a simulation is simply a question about whether there exists another universe containing minds who have the experience of operating a computer simulation which appears to contain minds having particular experiences, where those particular experiences happen to be identical to the set of all experiences had by all minds in this universe. Idealism could be equally true no matter what the answer to that question may be. The ontological status of this universe is completely independent of whether that separate simulating universe happens to exist; in principle, our universe could even be simultaneously simulated by multiple distinct simulating universes.