[mabub24]

> Basically what I'm trying to say is how can anyone who believes the brain is purely physical (not spiritual), believe that we just simply cannot achieve human-level intelligence by machine (no matter how complex the machine gets).

Obviously the brain is physical. But is consciousness? Is consciousness a thing in a physical sense, or an "experience", or something like a collection of powers and abilities? The two poles in the argument aren't between physical machine or religious spiritualism. There are other options, alternative positions that don't rely on Cartesian demons at the wheel, or souls, or even an inside-mental vs. outside-body distinction.

One thing my initial comment was pointing out was that the argument in favour of AGI, and which you're presenting, relies on an assumption: that computational intelligence, what you might describe as the intelligence of machines, is the same as the intelligence of humans. But that is just an assumption when you get down to it based on a particular kind of model of human intelligence. There are certain logical consequences of that assumption, and I've just pointed some out as probable roadblocks to getting to AGI from there. Many of those alternative positions, a lot from philosophy of mind, have raised those exact critical arguments.