What do philosophers do when they think about imagination? You may think they close their eyes, visualize an apple and then try to think hard about what they experience when they do so. Well, some (many?) philosophers of imagination do in fact do this at least to establish some of their premises. The aim of this piece is to argue that they really should not!

Take some of the classic debates about imagination: How does imagination differ from supposition? Imagine all the people living life in peace. Got it? Now suppose, maybe for reductio, that all the people are living life in peace. The two seem very different. To some people, but maybe not to others.

Or another classic one: does imagination necessarily involve the use of mental imagery? Imagining a circular square would entail filling out the details of what is imagined. This filling out would involve imagery, but given that such imagery is not available, we just can’t imagine circular squares.

It is difficult to settle disagreements about phenomenology. So, if someone says that: “Hey, I can imagine all kinds of things, but when I do so, I just don’t see anything ‘in the mind’s eye’”, it is not easy to know what argument could advance the debate.

Crucially, this is not a mere theoretical possibility. There is a recent body of research on subjects who have no conscious mental imagery whatsoever. There is even a cool-sounding name for this condition: it is called aphantasia. A surprisingly large proportion of the population (according to some measures 5-8%) have this condition: they lack conscious mental imagery. Each time I give a talk about mental imagery, there are quite a few aphantasia subjects in the audience.

Aphantasia is a label that covers a variety of underlying causes: some aphantasia subjects have problem conjuring up mental imagery, but when it is triggered automatically, they do have vivid mental imagery experiences. Others show the same behavioural and neural profile in mental imagery tasks as other subjects, but the phenomenology is entirely missing.

Aphantasia is one end of the spectrum. The other end is people with extremely vivid imagery experiences. Most of us are somewhere in between. And we know a fair amount about the neuroscience of what the vividness and precision of mental imagery depend on (roughly, the size of the primary visual cortex and its connectivity to higher areas).

The interpersonal variations in imaginative phenomenology – the extreme case of which is demonstrated in the aphantasia research – highlight just how unlikely it is that any great genius of a philosopher of imagination can read off a plausible account of imagination from her experiences as these experiences can’t be representative (as no imaginative experience is ‘representative’). The same goes for other philosophical debates where mental imagery plays a role, like the cognitive phenomenology debate.

The method of just introspecting and coming up with a philosophical account of imagination (and of other mental phenomena) has had a good run in the history of philosophy. But given the interpersonal variations in the imaginative (and other kinds of) phenomenology it is just not a very promising option.

Bence Nanay is Professor of Philosophy and BOF Research Professor, Centre for Philosophical Psychology at the University of Antwerp, whose research focuses on philosophy of mind, philosophy of biology and aesthetics, and primary investigator of the Between Perception and Action project and the Seeing Things You Don’t See project.