Throughout history, our predecessors in science and philosophy have been convinced that their particular understanding of reality was, at least largely, correct. Yet time and again, subsequent generations have proven—or at least were convinced of having proven—them wrong. Each generation has looked upon the ideas of their predecessors as naïve, simplistic, even superstitious.

During the Renaissance, scientists attempted to explain electrostatic attraction by postulating the existence of an invisible elastic substance—called ‘effluvium’—that supposedly stretched out across bodies. Strange as it may sound now, at the time effluvium was as plausible an explanation for empirical observations as subatomic particles today, which are equally invisible beyond the effects they putatively produce.

As the Renaissance gave way to the Enlightenment, scientists began trying to frame every phenomenon in terms of the action of small corpuscles—atoms—interacting with each other through direct contact. Any explanation that failed to conform to this template was considered an appeal to magic and therefore implausible, to say the least. This is why the ideas of an English scientist called Isaac Newton were ignored and even ridiculed for decades; Newton dared to propose that objects attracted one another from a distance by virtue of an invisible, mysterious force he called ‘gravity’. We know how that story developed.

Thomas Kuhn observed in The Structure of Scientific Revolutions that changes in science and philosophy’s sense of plausibility aren’t monotonic. They don’t progress steadily forward—they oscillate. Indeed, since Einstein’s general theory of relativity, we are back to rejecting the magical action at a distance that Newton thought gravity to be. Now, we have the much more plausible, reasonable, hard-nosed understanding that apples fall to the ground because the Earth… well, bends the invisible fabric of spacetime around us, as described by an entirely abstract Riemannian geometry that would have made Euclid scoff.

Please notice that I am not questioning the correctness of our scientific predictions of nature’s behaviour, insofar as they are empirically verified. General relativity unquestionably makes accurate predictions. So did Newton’s gravity and—yes—even effluvium in their own time. What I am pointing out is that the way humans think about these predicted behaviours—that is, our visualisation or mental picture of what is going on—can be regarded as either eminently plausible or utterly implausible, depending on the particular historical junction and culture from which they are considered.

Our current mental picture of gravity under general relativity—namely, curvatures of spacetime—may be considered utterly implausible in the future, even though that won’t change the fact that general relativity makes correct predictions as far as the sensitivity of our measurement instruments today allow us to determine.

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In this context, what Kuhn realised was that the mental picture our predecessors in science and philosophy had about what was going on was ‘produced by the same sorts of methods and held for the same sorts of reasons that now lead to scientific knowledge’. Yet, subsequent generations had excellent, even decisive reasons to consider them wrong. The inevitable implication is that we structurally believe in nonsense. There is no reason to think that things are different today. Future generations are bound to look back at our mental picture of the world and laugh at our myopia and obtuseness—our gullible tendency to appeal to magic.