I think the man is working on sheer instinct.

"At those times it's a matter of sheer instinct whether or not you will survive."

He was running this operation on sheer instinct, his subconscious in control.

He later said it was sheer instinct because "in 99 cases out of 100, you wouldn't throw home."

It was almost working, too, but his insistence on a supposed escort kept her mind clear by sheer instinct alone.

And sheer instinct rejected the idea that man would ever hurt Janet.

Without direction, and probably on sheer instinct, Richard has already taken precipitous action.

All was confusion; sheer instinct told him he ought to be someplace else.

Joe dropped from sheer instinct, and he was just in time.

And sheer instinct made her nod, which evidently was answer enough for him.