How Many Senses? Multisensory Perception Beyond the Five Senses

The idea that there are five senses dates back to Aristotle, who was one of the first philosophers to examine them systematically. Though it has become conventional wisdom, many scientists and philosophers would argue that this idea is outdated and inaccurate. Indeed, they have given many different answers to this question, ranging from just three (the number of different kinds of physical energy we can detect) to 33 or more senses. Perhaps surprisingly, the issue remains controversial, partly because it is not clear exactly what should count as a ‘sense’. Should we include hunger, thirst or tiredness, for example? And what about temperature, pressure, texture and pain? These are normally grouped together under the heading of ‘touch’, but could also be regarded as distinct senses in their own right. After all, we don’t need to touch the surface of an object in order to feel that it is hot. For example, we can feel the warmth of the sun by detecting the infra-red radiation that it gives out. As these examples illustrate, our senses are more varied and diverse than the traditional classifications of sight, hearing, touch, taste and smell suggest. But should proprioception, balance and kinaesthesis, amongst others, be considered additional senses? And if so, how do we figure out how many senses we really have?