Believing Without Seeing: a Dialogue

A: We should only believe in that which can be seen!
B: I don’t think you realize how radical a proposal that is.
A: How so?
B: Take consciousness, for example. You see me, and I see you. We are both visually aware of each other as we engage in dialogue, and we take it as given that, in the process of doing this, we are both conscious.
A: Right.
B: But you are not able to see my consciousness. Neither am I able to see yours. Neither has anyone ever seen anyone else’s consciousness. If we take your proposal to its logical conclusion, then we ought to conclude that none of us are ever conscious.
A: But of course we are conscious!
B: Yes, of course. But then the very fact that we are conscious cuts against your proposal. We probably should believe in some things which can’t be seen, because the cost of denying the reality of consciousness is far too steep.
A: I think that’s fair.
B: You could probably make a similar point with respect to one’s thoughts. We are not able to see our thoughts in any straightforward sense. You can crack open my brain, and you will not find my thoughts there.
A: Right, but that is a very crude account of what is actually going on in the brain. We know that our thoughts are intimately connected with the firing of synapses and other neurophysiological factors.
B: I don’t deny that. It’s certainly not new information that our thoughts and our brains are intimately connected. But it doesn’t straightforwardly follow from this that our thoughts are therefore reducible to our neurophysiology. I mean, our thoughts are also intimately connected to our behavior, and yet we wouldn’t take this to be evidence that thoughts are reducible to behavior.
A: I don’t think I’m following.
B: My point was simply this. From

x is intimately connected to y

you cannot derive the conclusion

∴ x is reducible to y

without bringing additional premises into the mix, such as the premise that all things can be explained in relation to matter.
A: That seems right. I suppose I just need to mull the point over.
B: Fair enough. But we have gone some way in conceding that we can’t only believe in that which can be seen.
A: Yes, I’m fine with qualifying my initial proposal.
B: I think it’s also worth pointing out that we reason backwards from effects to causes all the time. In other words, from things we can see, we often go on to affirm the existence of things we cannot see. This is especially true in the case of science. Remember that book from John Polkinghorne we read last month?
A: “Quantum Leap?”
B: Yes. I’ve yet to finish it, but this passage from page 31 stood out to me:

[W]hat doesn’t get mentioned is that no one has actually seen a quark. Scientists have confidence that quarks exist because believing in their existence explains other things. Other scientific knowledge makes sense if it includes the belief that quarks exist.

This is a clear instance in which believing in that which can’t be seen is actually necessary to account for those realities that are visible to us. Far from motivating the belief that only what is visible to us is real, the very task of empirical inquiry often forces us to postulate entities outside our immediate field of vision.