Instinct is that sense which cannot yet be explained. Often in some situations, all we can fall back on is instinct in order to help us make decisions. In my own case, I have seen that whenever I have ignored my instinct guiding me, I have suffered the consequences.
Instinct is there in consciousness in order to help us. Much of life is incomprehensible and humankind is definitely not all-knowledgeable. Even at the individual level, there are so many things in life which a person is unable to know. He just does not get the time to learn all that the race collectively knows. This is where instinct comes to his rescue.
Instinct teaches us trust. If we can trust our instinct, we can often avoid many dangers. Thus, this gift of nature, if cherished, works wonders for us and helps us travel through life safely.