Wonkish: Kant May Have Welcomed Paradox in Metaphysics, Just as Bohr Welcomed It in Physics

Deciding that two contradictory sets of reason were needed to allow for moral judgments or to explain the behavior of electrons may have been acts of genius, while still acknowledging the limits of human capacity to reason at all.

Niels Bohr accepts the inexplicable. What other choice?

I've wanted to know things with certainty all my life but have felt sadly lacking the capacity to be sure of anything at all. Yet I, like so many others, decide to accept what can be observed and intuitively "grokked," as Robert Heinlein framed it so well in Stranger in a Strange Land.

When I read the existentialists, my takeaway was that we could never really know anything and that that was very depressing, enough so that Camus, for example, had to reach for "the benign indifference of the universe" to not slit his wrists. But I'm off-topic a bit.

My point, though, is Kant's "I moralize, therefore I am" should read "I moralize, so sue me." As the authors of the paper "Paradoxes of Free Will and the Limits of Human Reason" go on to say: 

In putting forward his Epistemic Dualism in the latter part of the eighteenth century, Kant had anticipated the Epistemic Dualism of ‘complementarity’ of quantum physics, which had been put forward by Niels Bohr (1928) in the first part of the twentieth century. In his use of the term ‘complementarity’, Bohr did not refer to its ordinary, everyday meaning, namely the aspects of two different parts of a thing that make that thing a whole, such as the two “complementary” polynucleotide chains that make the DNA double helix a whole (as we might recall in this year of the Golden Jubilee of its discovery). Rather, under Bohr’s meaning, complementary aspects of the world give rise to rationally irreconcilable concepts, whose inconsistency can never be demonstrated empirically.

Bohr introduced his complementarity concept upon the advent of quantum mechanics and its epistemological paradoxes, such as the incoherent description of the electron in terms of a wave as well as in terms of a particle. According to Bohr, the wave-like propagation mode of electrons, on the one hand, and their particle-like mode of interaction with matter, on the other hand, each express an important feature of the phenomena associated with electrons. These features are‘complementary’ aspects of reality because, although they are mutually contradictory from a conceptual point of view, there are no observational setups under which they can be shown to be in direct contradiction empirically. The reason for this is that mutually exclusive observational setups—that is to say, different contexts—are required for demonstrating either the wave or the particle nature of electrons.

Bohr’s complementarity concept thus showed that Kantian Epistemic Dualism is not restricted to metaphysics, which is generally regarded as a soft discipline in which anything goes. As it turned out, Epistemic Dualism applies also to physics, which is revered as the hardest of hard disciplines, one that brooks no irrational inconsistencies.

These philosophical "decisions" -- in the hard sense of philosophy -- were made a long time ago, just as Einstein postulated a number of phenomena of the physical world that were proven through real observation decades later. We may never find the neurobiological proofs needed to establish free will and moral responsibility as real phenomena as, say, we've proven the existence of gravitational waves, but until we do, we'll have to get by through "grokking" them. It's the morally responsible thing to do.