The Beginning of Infinity: Explanations That Transform the World

by David Deutsch

Then you discover a cure that will cause your blue receptors to start working. Before administering the cure to yourself, you can confidently make certain predictions about what will happen if it works. One of them is that, when you hold up a blue card as a test, you will see a colour that you have never seen before. You can predict that you will call it ‘blue’, because you already know what the colour of the card is called (and can already check which colour it is with a spectrophotometer). You can also predict that when you first see a clear daytime sky after being cured you will experience a similar quale to that of seeing the blue card. But there is one thing that neither you nor anyone else could predict about the outcome of this experiment, and that is: what blue will look like. Qualia are currently neither describable nor predictable – a unique property that should make them deeply problematic to anyone with a scientific world view (though, in the event, it seems to be mainly philosophers who worry about it). I consider this exciting evidence that there is a fundamental discovery to be made which will integrate things like qualia into our other knowledge.