The World is a Black Box

The world with its quarks and chromosomes, its distant lands and spiral nebulae, is like a vast computer in a black box, forever sealed except for its input and output registers. These we directly observe, and in the light of them we speculate on the structure of the machine, the universe. Thus it is that we think up the quarks and chromosomes, the distant lands and the nebulae; they would account for the observable data. When an observation turns out unexpectedly, we may try modifying our theory of that structure at one or another point. When an observation shows that a system of beliefs must be overhauled, it leaves us to choose which of those interlocking beliefs to revise this important fact has come up repeatedly. The beliefs face the tribunal of observation not singly but in a body. But note now that the observation sentence itself the sentence that reports or predicts a present or imminent observation, is peculiar on this score. It does face the tribunal singly, in the usual case, and simply stands or falls with the observation that it reports or predicts. And, standing or falling, it sustains or lets down the system of beliefs that implied it.

We don't know how it works, we only see the inputs and outputs and must extrapolate hypotheses from what we see.