Er, yes. And mediation of all those processes requires at some point photon exchange, mmkay?
Mmm-no. Explain to me how smelling involves "photon exchange". Actually, what is "photon exchange"? Photon is light. The energy of a photon can be "exchanged" by various processes like scattering or absorption. But the photon itself ceases to exist when absorbed, and if a photon is reradiated by some medium (scattering), the photon has a new k vector (direction) and is a new photon. So I could understand light scattering as "photon exchange", but our perception of the external world is not mediated by photon exchange.
Seeing, yes.
Listening, hearing, feeling, no.
Whether "we" are brains-in-vats or what we 'think' we are ... thinking beings in an objective external reality ... thought exists.
Unfortunately, every thought is based on information from some world external to the brain. For a thought to exist, you have to think about something. And that thought requires some mysterious process to exist, or simply some electrochemical activity.
For discussion, we can agree I Think, and You Think.
Technically, if I take a physicalist approach, I can agree with you.
But if I take the objective idealistic approach, do I have any reason to believe that you think? I have no evidence that anybody thinks. If I believe you think, I'm making an assumption that you operate the same way I do. Only my own thoughts can be verified by myself, I cannot verify the nature nor the content of your thoughts.
Yeah, whatever external reality is it's objective so far as my 'thoughts' have ever effected or affected things. Yet my 'thought' does seem to direct, what I perceive as 'my' body/brain, and that effects and affects external reality.
Sure, but your brain perceives an external reality AND an internal reality. You have an inner voice, an internal moviescreen. You can actively manipulate these things with your thoughts. Why not the external stuff?
Therefore I choose "objective idealism" as my logically defensible position. Now "my physical stuff" is my epiphenomena, and 'my thought' is the causal agent that controls events. Much of the machinery appears to run on auto-pilot and my conscious intervention may never over-ride 'my environmentals' that keep some the perceived physical stuff operating.
The major problem I have with this approach is that at some point, you should be able to affect the external world through your thoughts alone. Why the need for your body? You don't even know for sure if your body exists, only your thoughts. Why can't your thoughts do all the work that your body seems capable of doing?
Much of the machinery appears to run on auto-pilot, but what is the implication of that appearance? Why isn't there more work at figuring out how to use your thoughts (the only thing you know exists) to manipulate that machinery that seems to run on auto-pilot? Okay, sure, cause everybody assumes physicalism, whether they know it or not.
But what is the fantastic implication that objective idealism holds for humanity? Especially since a physicalist approach to learning "appears" to hold new knowledge about the very processes in which we think and have thoughts.