At least from Hegel on, indeed perhaps since Plato and Aristotle, philosophers have cherished the idea of a form of rational progress that is rationally irreversible. Professor Sophie Grace Chappell explores a number of forms of this idea, including Hegel’s own, Plato’s, Francis Fukuyama’s, and Bernard Williams’, and she contrasts the idea of rational progress in science as discussed by pessimists like Kuhn and Feyerabend, and relative optimists such as Lakatos and Popper. Professor Chappell also explores the question whether an experiential enlightenment might be rationally irreversible, as conversions are sometimes supposed to be, or transformative experiences or epiphanies, or moments of self-discovery such as “realising one is transgender”.
Her findings are moderately pessimistic. None of these forms of enlightenment is either infallible or irreversible. Indeed all are reversible not just by brainwashing but by something like rational argument--though of course, if we have to do with a genuine form of enlightenment, the rational argument will be misguided argument.
To illustrate her pessimism Professor Chappell takes the phenomenon of “detransition”, and parallel phenomena where a fundamentalist upbringing ultimately wins out over a liberal inculturation in a process that its victims call “repentance” and “seeing the light”.
Her conclusion is not that our situation is rationally hopeless, but it is that we should abandon the false hope of a Hegelian magic-bullet story about Reason Unfolding In History. “The triumph of reason” is not inevitable; but neither is the triumph of what she will deliberately-abusively dub the new stupidity. We just have to slug it out, at the level of patient and persistent detail in particular debates.
And this is worth doing. Free, liberal, and humane societies are historical rarities, and the progress that they represent is as a matter of historical record extremely patchy and very easily undone. Enlightenment is not irreversible, but very fragile. Nonetheless it is a wonderful achievement, and well worth fighting to keep.