We are gaining insights, also, into aspects of the mind that may be uniquely human. Dennett, surely rightly, highlights “displaced reference” as a key innovation of language, its “power to refer to things not present in the environment of the communicators, out of sight, in the past, imaginary or hypothetical”. But while language is uniquely helpful when I want to tell you what I think, it is only one of many ways of achieving this kind of reference. When I imagine the house in which I spent my childhood, many leagues hence, I also represent a thing not present, and for most of us such ‘“visualisation” plays a large part in our mental lives. With colleagues in Edinburgh I recently described a group of people who lead “lives without imagery”. It seems that two per cent of the population may fall into this category — not least Standpoint’s own Dominic Lawson. Such “aphantasia” had a distinctive neural signature in the first such case we studied: in the several thousand who have since volunteered intriguing associations are coming to light, including, in many, an impoverishment of memory for the personal past, an impaired ability to recognise familiar faces, and — here’s the fun and the puzzle — abundant potential for the highest achievements in both the sciences and the arts: Craig Venter, the first person to decode the human genome, and Oliver Sacks, the great chronicler of neurological disorders, have both described their lack of imagery.

Aphantasia, like synaesthesia, the “merging of the senses” that allows some of us to taste Tuesday or to see it emblazoned in crimson, illustrates the great — and often unsuspected — variety of human experience. Discovering that these differences between us correspond to differences between our brains helps to validate our introspection. The hundred thousand million neurons of the human brain, each connecting to thousands of other cells, those connections shaped by our lifetime’s experience, provide the biological background to Roger Scruton’s remark that we are “unique, irreplaceable, not admitting of substitutes”. The neuroscientist can wholeheartedly agree. Our uniqueness is a property at once un-mysterious and miraculous — much like the privacy, the “inwardness” of our experience: we contain multitudes, bounded by the narrow confines of the skull, unavoidably committed to a single point of view. We are strangely insensitive to the astounding complexity within the human frame. It gives us a powerful reason to respect and to reach out to one another, to transcend our tribalism.