Café Philos: an internet café

My senses tell me I'm sitting in a solid chair. On the other hand, physics tells me the chair I'm sitting in is mostly empty space. How can it be there is a difference between my subjective impression of the chair and what physics tells me is objectively true about the chair?

The short answer is that my brain and nervous system (very much including my senses) do not reconstruct reality as it is. My eyes do not, for instance, see the atoms of my chair, nor the empty space between the atoms. Instead, my eyes take in photons that have bounced off the atoms of the chair. My eyes and brain then process and interpret that information. In the end, what I see bears little resemblance to what is actually there according to physics.

One way to understand the relation between my subjective impression of the chair and what physics tells me is objectively true about the chair is to consider the analogy of a pilot landing an aircraft on instruments. Although the plane's instruments give the pilot very little information about the world -- and even though what information they give him is highly processed and interpreted -- the information he gets is sufficient for him to navigate. Just so, our brains and nervous systems give us very little information about the world and the information they do give us is highly processed and interpreted -- yet it's usually sufficient for us to cope with the world.

We are all like that pilot -- we must cope with the world on instruments alone. That's the position our brains and nervous systems leave us in.