do you believe in a sixth sense?
You mean like “I see dead people” or precognition or something like that? No.
But there are more than 5 senses, for example proprioception (the sense of the relative position of the parts of the body and strength employed in the movement of the body) it’s just one of other very important senses that we human have (other animals have other senses, plant have senses too).
In ‘The Man Who Mistool His Wife for a Hat and Other Clinical Tales’, Oliver Sacks describes the case of a woman who have lost the sense of proprioception: ‘The Disembodied Lady’. Trust me, even if it’s a sense we don’t normally count, you don’t want to lose proprioception.
