Mary was a super scientist. Her chosen field was the study of light and colour. She applied herself with diligence to her studies and rapidly consumed a number of textbooks. She masters the nature of light, its constituent coloured parts with their wavelengths and associated energies. She understands fully how light behaves when passing from medium to medium and could tell you exactly how light interacts with the photoreceptors at the back of your eyes, cells which convert the light into a signal interpretable by your brain. Suffice to say, there is nothing about light and colour that she does not know.

But there is one thing Mary lacks. You see Mary has lived in one room all her life. And that room is entirely black and white. Her textbooks are black and white, the desk where she works and calculates refractive indices is black and white. She has lived a life in monochrome.

When the door to Mary’s room finally opens, and she steps out into the world, she finally experiences for herself these colours which she knows so much about. Her mind is flooded with a new awareness, a sensory extravaganza which till now had been an empty hole in her existence. It wasn’t true that she knew everything about light and colour. She knew everything except for what it feels like to experience colour. That piece of knowledge was missing.

Now imagine that Mary had a brother named Fred. Fred lives in a monochrome room adjoined to his sister’s, but he was nowhere near as studious as her. Far from diligently hitting the books and mastering the intricacies of visible light, Fred whiled away his time mucking around with a black fidget spinner; round and round and round, day after day. When the door to Fred’s room opens, he too steps into a new, polychromatic world. He learns exactly the same thing as his sister: he learns what it feels like to experience colour. There is no difference in terms of the thing which they have both learned.

But surely their experience, their feeling in that moment, is different. Fred is certainly struck by the sensory overload, but the feeling passes. It is shallow, disembodied. Mary’s experience here is completely different. She gazes in awe at this world around her finding new wonders and meaning wherever her eyes fall. That grass is green! A wavelength of 550nm! Red and blue light are being absorbed, and green being reflected. And the grass is ever so slightly shiny, that’s the dew on the blades creating a reflective surface for incident light to be bounced to me from the Sun, all at the same angle creating a glistening sheen. I’ll bet if I looked closer I would be able to see coloured glints in the corners of the dew drops, miniature rainbows cast from the Sun’s bright light. But look! The walls of that house are matt – the surface is rough and the light bounces at all sorts of angles, so the red colour has no sheen. And on, and on, wherever her gaze rests.

Mary’s experience of the world is enriched and ennobled by her knowledge of it. Despite learning exactly the same thing as her brother, she feels it more. It runs deeper into her marrows and finds itself expressed as a kind of joy, an excitement at being able to place and concretise all that knowledge.


I was honoured to speak on the ResearchEd strand at the Festival of Education today. I was talking about facts and knowledge and how they help us learn, think and create. For regular readers of this blog, little of the below summary will be news to you:


The first four are staples of the cognitive sciences and you probably have a good understanding of them anyway. In the slides I’ve tried to explain exactly how it all works (with some evidence of course) and there are a couple of exercises and problems you might not have tried before. Mary the super scientist of course relates to number 5 though, and it’s not something I’ve seen much about before. It’s a thought experiment by Frank Jackson and comes with some super long words like “epiphenomenal qualia” but I think it sheds light on an under-discussed “use” of knowledge: that it enriches and ennobles our experience of the world. I would be really interested if anyone has any thoughts or has seen any literature looking at ideas like this.

Slides are here: Facts – I tried to put as many notes in the comment sections as I could. Please be in touch if there is something that doesn’t make sense.

Further reading: Obviously Why Don’t Students Like School is the first thing to read, followed by 7 Myths About Education and Why Knowledge Matters (which I haven’t got round to yet). I referenced John Searle a bunch of times and I recommend either Mind or The Mystery of Consciousness. He also has a bunch of lectures online which are easy to find.