I don't know. His explanation sounds pretty good to me, given that explanations can only go so far when the entirety isn't known.
If you've never been to the next state over, you can still speculate on it based on what you know of your own state, and I think that's reasonable. But, it's only speculation and probably fraught with errors.
That's what Feynman is trying, better than me, to say. We probably have 1% of the physical universe reasonably well understood. Outside those boundaries, all we can do is extrapolate based on what we DO know.
And then, invariably, someone asks if we really know anything. Maybe it's all an illusion, they wonder. Yes, maybe so. But that's a pointless avenue of thought, isn't it?
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