Recently, a friend asked me – How do you know that rationality presents the real picture of reality? I thought of David Hume who said that – “we really have no rational reason to believe in objective reality but we also have no choice but to act as if it is true”. Stephen Hawking’s new book compared human position with that of a fish in the jar in a model-based framework of reality. This metaphorical fish can also identify regularities within the jar and formulate natural laws based on how, for instance, light behaves in water or how the world outside appears from the jar. Hawking asserts that these laws would hold true everywhere within the jar, but the fish would have no way of detecting if these laws are actualized outside the jar.
As we examine the neural substrates of sensorimotor processing and how external stimuli are projected to contrive a model of the external world, there’s little in the way of suggesting any hard correspondence between the perceptual model and the “real” picture of reality, if there’s such a thing. In this framework, the whole enterprise of reasoning and empirical verification is circulus in probando at best, for it is inherently limited by our sensory modalities and faculties of reasoning. How do we know then that the model of reality, as we perceive it, is any more real than the one formulated by the fish in the jar? Some argue therefore that we have no “truly empirical” way of deciding whether we can trust rationality and empiricism to present us with a real picture of reality.
But Hume died in 1776 and we have made tremendous progress in last 240 odd years since his passing. Do we now have a slightly more ‘rational’ reason to pursue the rational inquiry? To quote one of the professors of philosophy in my university – “We know a lot more now than Hume did. This is manifest not only with what we take to be true, but with our extended mastery of the world insofar as we can exploit regularities present in it to our advantage. Now, I suppose one can challenge that we have learned anything about the conditions in which my perceptual apparatus is a reliable indicator of properties of the world, but that seems just to rehearse the global skeptical hypothesis. There is simply no way to refute a globally skeptical hypothesis when a characteristic of the hypothesis is that we couldn’t possible have any evidence that would undermine it.”
(To be updated)