Reddit reply in r/PhilosophyMemes: move over solipsism new fear unlocked — December 1, 2025 · nrrius8 | Ali Shukri Amin

You’re still confusing two different probability questions.

1. The entropy trajectory after life exists

Evolution increases entropy over billions of years.
That’s true and completely irrelevant to my point.

2. The entropy barrier required for something to exist in the first place

A Boltzmann brain requires a local, low-entropy fluctuation on the scale of a single organ.

At one point you are even denying that there can be localized variations in possible states of entropy, as if the universe is a homogenous energy distribution constantly increasing in entropy without any instances of low entropy.

Life-as-we-know-it requires:

1. Stars forming
2. planets forming
3. stable chemistry
4. self-replicating molecules
5. cells
6. nervous systems
7. multicellular organisms
8. 3+ billion years of evolutionary history
9. trillions of fully-formed human brains

You’re describing the entropy increase after the initial step, but the initial step itself is an astronomically low-entropy event.

A biosphere doesn’t just “follow entropy increase”, it starts with a massive entropy drop to generate any ordered replicator at all.

Boltzmann brains: tiny entropy drop (on a localized scale)
Entire biosphere + evolution + trillions of minds: incomparably larger entropy drop (on a localized scale)

That’s the only comparison I’m making.

On the card-shuffling analogy:"You’re actually making my point for me.

> “The number of possible arrangements of 52 cards is enormous.”

Exactly — and the number of microstates corresponding to one specific biological evolutionary history from RNA → humans → trillions of brains is orders of magnitude smaller than the number of microstates corresponding to “a single functioning brain appearing briefly.”

You're comparing the wrong levels of complexity:

One brain with coherent firing patterns vs. A universe that produces billions of species and trillions of observers through chemical evolution

They’re not in the same league.

On ‘we don’t know how many times life started’

That doesn’t matter for this argument.

The Boltzmann brain reasoning isn’t:

> “Life is rare so BBs must exist.”

It’s:

> “If fluctuations are a mechanism at all, then small fluctuations are astronomically more probable than large ones.”

That’s a statement about relative microstate rarity, not biology.

On “you being an evolved brain is more likely”

That’s true only if you assume the universe is low-entropy and chemistry-dominated from the start and that life has begun. That is exactly the assumption that the Boltzmann brain argument challenges.

If you assume a fluctuation-dominated cosmology, then small-brain-first is more likely.

A non-homogenous entropic system is presumed regardless whereas the Boltzmann brain argument refuses to assume that life exists. That's the entire argument.

My entire point is:

In any universe where fluctuations exist at all,
the entropy barrier for “1 brain” is vastly lower than the entropy barrier for “biosphere + evolution + trillions of brains.”

Either you are arguing we live in a state of homogenous entropy distribution and therefore life doesn't exist or you concede that on a local, smaller, scale there can be low entropy fluctuations and life does exist. If you agree life does exist, then it only follows that less dramatic fluctuations are MORE PROBABLE than trillions of much lower fluctuations in succession.