### **Clarification on Possibility, Computation, and Physical Constraints** If I had to guess what my dad is getting at here, I think he might be asking, _“Can we even simulate consciousness? Can we simulate existence itself?”_ He seems to be approaching this from the **simulation** side of the argument—which, for the record, I think is a perfectly legitimate angle. # Clarify Computational Universality If you accept that artificial general intelligence (AGI) is possible—which I do—then you’re already on board with the idea that minds could, in principle, be simulated. So that’s not really the issue. What I think **is** worth clarifying here is that someone might push back and say, _“Wait a second, Nate, didn’t you just argue that appealing to ‘what’s possible’ is too broad and a bad move? Aren’t you doing the same thing here?”_ And I think the clean response is: _“No, that’s not what I’m saying at all.”_ I have **no problem** using our **best-known theories** to reason about **what’s possible**, **what’s realistic**, and **what the boundaries are**. The key is that we’re not talking about **pure logical possibility** (which is unconstrained and includes anything you can imagine). We’re talking about **what is physically possible**, based on **the best explanations we have from physics**. So if I were to frame it more precisely, I’d say: - _Here’s what our_ **_best physical theories_** _tell us is possible._ - _Here’s what they tell us is_ **_ruled out_**_._ For example, because of the **universality of computation**, our best understanding of physics suggests that **any physical process, including the brain, can be simulated computationally**. The brain is a physical system, so it follows that **it could, in principle, be modeled computationally**. Now, someone might say, _“Well, aren’t you just doing the same thing as Moravec? You’re saying everything is computational, so you’ve imposed no real constraints at all.”_ But here’s the distinction: I’m not appealing to **pure logical possibility**; I’m appealing to **physical possibility**, based on **actual scientific theories**—like computational universality, as implied by the known laws of physics. That’s **not** the same as saying “anything goes.” It’s saying “anything that fits within these physical constraints goes.” I actually think this is an important point to flesh out, because I can see how this might look like a weak spot in the argument if it’s not carefully distinguished. I’ll make sure to explain that when I respond to my dad.