Philosophy emerges as a series of arguments without end, and its questions settle into seemingly intractable problems.
Here is a companion thought experiment, now called the knowledge argument. By reading the appropriate books, you could learn all about the chemistry of ammonia. By reading more books, you could learn all about how the human olfactory system works and, in particular, how it reacts in response to ammonia molecules – what distinctive changes occur in the mucous membrane and in the olfactory nerves. Given all this textbook information, though, could you then know all there is to know about the smell of ammonia? Or is there something about the smell of ammonia, the qualitative experience of that sharp, pungent aroma, that you won’t understand from this learning, independent of experience?
It seems that knowledge of the aroma of ammonia – what it actually smells like – is not the kind of information you can get from reading books. But then are there facts about human experience that can’t be captured by science and what it can report in its textbooks? Is there more to us than is scientifically describable? If so, it implies that humans aren’t purely physical systems – a remarkable exception to what the natural sciences otherwise tell us about the world.
These thought experiments and others like them generate debates that run and run. It’s not simply that there are different sides to take on any one of these puzzles. It’s that a strong opening case can be made and sustained for each of these viewpoints, despite the fact that these viewpoints conflict.