All 4 Uses

positive
in
The Chrysalids
(Edited)

We did not, and because we did not, we had no positive — we were condemned to negatives, to not revealing ourselves, to not speaking when we would, to not using what we knew, to not being found out — to a life of perpetual deception, concealment, and lying.
Chpt 9

positive = good to do
As far as I was concerned a firm grasp of the negative in the cause of survival had been quite enough to occupy me; I was only just beginning to perceive the vacancy left by the absent positive.
Chpt 9 *
One of the things we looked forward to most was relief some day from that burden, and though we'd few positive ideas how it could be achieved, we could all realize that marriage to a norm would become intolerable in a very short while.
Chpt 10

positive = good
It was odd, I felt, how many people seemed to have positive, if conflicting, information upon God's views.
Chpt 14 *

positive = certain

Definitions:

(1) (positive as in: I'm absolutely positive!)
certain (having no doubt; or used for emphasis)
(2) (positive as in: had a positive effect)
good or beneficial
(3) (positive as in: positive feedback from my boss)
approval or agreement
(4) (positive as in: a positive attitude)
optimistic (expecting or focusing on good things); or agreeable
(5) (positive as in: The test came back positive.)
found a condition or substance to be present
indicating the presence of something being tested for -- especially a disease, condition, or substance
(6) (positive as in: a positive number)
greater than zero (of a number)
(7) (meaning too rare to warrant focus)
See a comprehensive dictionary for less common meanings of positive including some in the fields of electricity, physics, chemistry, medicine, philosophy, and grammar. Note that most all senses of positive indicate that something is good or present.