> Nagle, for example, might say that first hand knowledge absolutely exists, but it is "off limits" to anyone but the organism experiencing it.
If physicalism is true, then all facts must be reducible to the physical.
If everything is reducible to the physical, then the experiences of the organism are also so reducible and must have a third-hand description.
If experiences are not so reducible, then physicalism is false and no amount of third-hand knowledge can produce first-hand knowledge.
These are exhaustive and mutually exclusive options.
> I'm not sympathetic to Dennet, but there are other options than first hand knowledge simply not existing within materialism.
The meaning of first-hand knowledge in physicalism is different from the meaning of first-hand knowledge in other metaphysics. In physicalism, first-hand knowledge must be reducible to third-hand knowledge, and so it doesn't have a privileged ontological status, just like we don't ontologically commit to the existence of cars in quantum physics.
So first-hand knowledge cannot really exist in physicalism except as a useful label describing a specific kind of third-hand knowledge.