Name the principle behind sixth sense?

Prescience would possibly be considered the sixth sense.

BUT that is not a sense in the usual way. In addition to the usual five senses that are spoken of, [touch, sight, sound, ... .] we have quite a number of other senses. Your sense of balance is of great use, and with touch, there are at least three differentiations of these.

The feeling of a sixth sense is often felt because we subconsciously perceive some disagreement within the natural senses, and we become alert, but without knowing why.