Christian Jarrett has an interesting article at BBC Future on the number of senses that we have.

The principle of five basic human senses is often traced back to Aristotle’s De Anima (On the Soul), in which he devotes a separate chapter to vision, hearing, touch, smell and taste. Today, the five senses are considered such an elementary truth that it is sometimes used as a point of consensus before writers embark on more mysterious or contentious topics. “What do we actually mean by reality?” asked the author of a recent article in New Scientist magazine. “A straightforward answer is that it means everything that appears to our five senses.”

If only it were that simple. Simply defining what we mean by a “sense” leads you down a slippery slope into philosophy. One, somewhat vague, definition might argue that a human sense is simply a unique way for the…