Nociception is the ability to feel pain.
It simply allows you to feel and identify pain, in order to protect yourself from it. A defensive system linked to the nervous system is essential for survival!
Pains depend on the individual, who experiences them, their representations, their history, their culture. The plurality of these pains therefore refers to an eminent singularity. Therefore they will always escape somewhat from the rational requirement of cartesian rigor.
How do you define your pain?