[chispamed]

It's really difficult to draw a line between being our "selves" and the alternatives though.

We are not the individual cells of our body because most of them will be replaced in the next weeks/months/years. We also don't think of any body with a knee replacement as any less human. Even altering the genetic code of a huge part of your body, like after stem cell transplantation, is not commonly seen as making us less us.

Also suppose it was possible to build a synthentic neuron that behaved just like the ones inside your brain. If you started replacing your neurons with the synthetic ones, no individual neuron would "change" you. So were would you draw the line? At 10% synthetic neurons? At 20%? At 100%?

If we see ourselves as biological beings another interesting point is how you would view a 1:1 copy of yourself. If we constructed a synthetic human that had the exact same number of molecules in the exact same place as you, would that human be you? (Leaving aside that that's basically impossible, just as a thought experiment)

If you answered the last question with "no", that would also mean that not even the way we process information and think makes us us, since the 1:1 molecular clone would behave exactly the same as you in the same environment (in a purely deterministic universe at least, leaving aside probability and Heisenberg's uncertainty principle).

So are we instead an uninterrupted instance of a thinking process? That would allow us to differentiate us from the exact clone. However in that case, would you be another person after being unconsciousness? What about general anesthesia? This really keeps me up at night.

It's next to impossible to define what we are and that we think of us as independent, unique beings might just be an illusion.

[lisper]

> This really keeps me up at night.

Why? You're pretty close to the right answer:

> are we instead an uninterrupted instance of a thinking process?

No, for the reasons you described. What we are is thinking-processes with a coherent series of more-or-less-uninterrupted links to the past. When you undergo general anesthesia you wake up as the same person because you can remember who you were before anesthesia, and you feel and act like that person.

The interesting case is not anesthesia (or sleep) but amnesia and traumatic brain injury or mental illness that changes your personality.

[chispamed]

I understand where you're coming from, however I think that remembering the past is not a very helpful criterium since memories correspond to physical changes in the brain. In the thought experiment, the 1:1 molecular clone would have the same memories and think that he had lived through the same things as the original human for what it's worth. I'm not yet convinced that it is possible to define one self even though our (physiological) human experience definitely makes us feel like we were this clearly defined, independent, conscious thing.

But of course the conditions you mention are also very interesting and make it non-trivial to define the "true" essence of the person. Another interesting one would be dementia.

[lisper]

> In the thought experiment, the 1:1 molecular clone would have the same memories and think that he had lived through the same things as the original human for what it's worth.

That's right. Why is that a problem?

Imagine you had this done to you, and imagine that in order to clone your brain you have to be put under anesthesia (because the process takes time and you need to capture a coherent snapshot). When you wake up, how are you going to tell whether you are the clone or the original?

[chispamed]

I don’t see it as a problem per-se, it just defies the notion of having a somehow unique, identifiable self which I understood as a condition for OP’s question and which I suppose is how most people view themselves.

As far as I’m concerned we might very well be just processes that can in theory be copied and recreated. In that case the person in the thought experiment would exist twice at a single point in time and then diverge into to different persons due to different environments and probabilistic processes in the body.

[thaumasiotes]

> As far as I’m concerned we might very well be just processes that can in theory be copied and recreated. In that case the person in the thought experiment would exist twice at a single point in time and then diverge into to different persons due to different environments and probabilistic processes in the body.

This already happens, though before the formation of any memories. We call them identical twins.

The divergence is more limited than you might imagine. One striking experiment found that if you separate identical twins and give them the instructions "just draw whatever comes into your head", they are likely to draw the same things.

[lisper]

> a condition for OP’s question

that being:

> If we remove our "selves" from our bodies, are we still us?

But answering this is now a straightforward thought experiment. You just approach it incrementally.

If you replace your limbs with prosthetics, are you still you?

If you get a heart-lung transplant, are you still you?

If you get an artificial heart, are you still you?

etc.

> a somehow unique, identifiable self which ... is how most people view themselves

Well, yeah, but that's a limit of our present technology, not necessarily a fundamental aspect of what it means to be human. Technology redefines the answer to that question all the time.

[mLuby]

Good points. Nevertheless, until we have a convincing answer to this, I have to treat mind uploaders and destructive teleporters as murderboxes.

[Koshkin]

> knee replacement

For what it’s worth, I think that in the process of gradual replacement of human organs with their “mechanical” equivalents, the brain will not be the last one to be replaced.