What is the probability of an afterlife of some type given all you know.
I'd put it at roughly **5-10%** for some form of personal conscious afterlife, though I hold that number loosely.
Several things push it down:
- **Brain dependence:** Consciousness depends heavily on brain function. Damage to specific regions alters personality, memory, and awareness, and when the brain stops working, the evidence for ongoing experience disappears.
- **No confirmed mechanism:** We have no accepted account of how consciousness could persist without a functioning brain or be transferred to something else.
- **Near-death experiences** are vivid and widely reported, but they occur under conditions like oxygen deprivation, and researchers have plausible neural explanations for many of their features.
Several things keep it above zero:
- **The hard problem:** We don't fully understand why physical processes produce subjective experience. That gap is real, and I'm not confident it will be closed in a way that rules out every possibility.
- **Definitional breadth:** "Some type of afterlife" covers a lot, from reincarnation and cosmic consciousness to information persisting in some form. Some of these are more plausible than a traditional heaven, and some are hard to test at all.
- **Limits of current knowledge:** Our understanding of consciousness is young, and I could be wrong about what's possible.
My estimate also reflects a judgment about how to weigh the evidence, not just a calculation. Other reasonable people, including some serious philosophers and scientists, would put it higher or lower. The answer depends a lot on how you define "afterlife" and how much weight you give to first-person reports versus physical evidence.
What is the probably of cryonics working given all you know?
My best estimate is **low, roughly 1-5%** that a person cryopreserved with current methods is ever revived with their memories and personality intact. I hold that number loosely, and the reasons matter more than the figure.
**Reasons for doubt:**
- **No mammalian brain has been shown to be revived after cryopreservation.** Nothing has been demonstrated beyond small-scale tissue preservation.
- **Damage is severe.** Vitrification avoids ice crystals but requires toxic cryoprotectants, and cooling can cause cracking. Brains also begin deteriorating during the period between cardiac arrest and preservation.
- **Structure may survive where function doesn't.** Some studies show brain ultrastructure can be preserved well enough to trace synapses, which is a real but limited result. Whether that encodes the information that makes you *you* is unknown.
- **It requires a long chain of future breakthroughs:** reliable reversal of the damage, and either biological repair or reconstruction via nanotechnology or whole-brain emulation from the preserved structure.
- **Institutional risk:** organizations must survive for decades or centuries, keep funding, and keep patients stored properly.
**Reasons it isn't zero:**
- Nothing in known physics forbids it in principle. Information loss is the central question, and it isn't settled.
- Future technology could be far more capable than anything we have now.
**The bigger uncertainty** is philosophical. Even if a preserved brain were perfectly reconstructed, it's debated whether the revived person would be the same individual or a copy. So "working" could mean different things to different people.
If you're considering it for yourself, the decision really rests on how you weigh a small chance of an extraordinary outcome against the cost, and on your views about personal identity. Those are questions where reasonable people disagree.
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