Selection by Consequences
Selection by consequences is the principle, foundational to Paper Two's argument, that behaviour is shaped by the outcomes that follow it. B.F. Skinner argued behavioural selection occurs at three levels — ontogenetic (within an individual's lifetime), phylogenetic (across generations, via natural selection), and social/cultural (via group-level transmission). The premise traces back to Thorndike's Law of Effect, and while much of the surrounding detail has since been challenged, the core claim — that individual behaviour is determined by its consequences — has held.
Reinforcement and punishment
Behaviour Analysis categorises consequences as reinforcing (desirable/rewarding — increased resources, social approval, higher status — which increase the likelihood a behaviour recurs) or punishing (undesirable/aversive, which decrease that likelihood). Reinforcement and punishment are not isolated events; they are often heavily socially mediated. Behaviour selection is an active, path-dependent process, based on the mental models an individual has built of likely consequences through observation and experience — and for a consequence to shape behaviour at all, reality has to go on satisfying the expectation it creates; an expected consequence that fails to materialise won't catalyse change.
This three-level selection framework is the scaffolding the paper builds the Neurobiological/Fitness Gap on top of: it is specifically the relationship between neurobiological and fitness-relevant consequences (see Consequences) that the gap concerns.