If it is infinitely more likely that I am a Boltzmann Brain than not, isn’t it also extremely more likely that I’d be one with any number of random memories rather than a group of memories that form a more or less coherent whole?
Of this range of possibilities, ones giving you a seemingly coherent and ordered timeline of experiences, or one that is disordered but close enough to order that it can be readily can be interpreted as ordered, would appear to be more improbable.
>on that small of a timescale, your existence is really just a single instantaneous snapshot of a state of mind, and there’s no time to recall a sequence of memories or think through logical propositions.
I think this is very true. Even being around long enough to pose the question to yourself gives you reasonably strong confidence that you've 'tested out' of being a boltzman brain. Though I think that consideration is being momentarily set aside for purposes of this variant of the thought experiment.
Why do you think that? A Boltzmann brain will immediately start to degrade but that does not mean there is zero time for thought.
If I were a Boltzmann brain, I would spend most if not all of my existence dwelling, contemplating, ruminating over the things that took me to my current point in space and time. Then I would quickly type something up and post it on a forum to confirm that I
Coherent memories are the convergent result.
> my memories are chronological and all feature me as the self
I’m not sure exactly what you mean by this, but the way I read it, I disagree with this as a description of human memory.
All my memories point to be me being not just human, but a particular human. In every memory I have, I am male, human, on Earth, live in the United States, live between the period of my birth and now. Speak English. Have the same number of siblings. etc. There's a more or less consistent story there.
And the story is chronological. You could argue that the timeline of events is arbitrary and my brain is just remembering them in the order of that makes sense. But I also have memories of remembering things, and in each one of those, I am remembering things that happened before the time I am remembering them.
The odds against a Boltzmann Brain having even two random memories that relate at all are incredibly small. The ratio of ordered:non-ordered Boltzmann Brains would be roughly on the order of actual Brain:ordered Boltzmann Brain. That's true even if we include a little wiggle room for the way the brain deals with memory.
The likeliest scenario is then that we are not Boltzmann Brains and any explanation of the universe that includes the probability that we are Boltzmann Brains is probably wrong in some way.
I often have perfectly clear memories that don't fit into any cohesive story. I reject them under the assumption that they're a dream leaking into my waking subconscious, or neurons going crazy, or whatever. (If this were a sci-fi movie, they might be critical foreshadowing!)
I wouldn't describe memories as inherently chronological. They're an unordered heap, with various indexes. Time is one such index, but a weak and incomplete one. I often misremember the age (or relative age) of events. Location and mood are much stronger indexes.
I haven't had any memories of being a Martian, true, but given that there seems to be some automatic filter already (most dreams don't become memories), it doesn't sound unreasonable that my brain has a GC of sorts. Perhaps my filter threshold is set too low, but still high enough to reject the Martian memories.
I agree that Boltzmann Brains are not the most likely explanation, but reflecting on how my memory works doesn't seem to be a good argument against that scenario.