People already behave differently in different settings, which shows the capacity is there

The argument

A second argument proceeds from something nobody disputes. The same person is gentle at home and curt at work, scrupulous with one friend and careless with another, calm in an emergency and impossible about small inconveniences. Behaviour varies enormously by setting, by role, by who is watching and by what is at stake. Whatever a person's character amounts to, it plainly does not issue one behaviour in all conditions. Proponents take this to settle the question of capacity. If someone already produces markedly different behaviour depending on the circumstances they are in, then the repertoire is not fixed, and the behaviour that looks like their unalterable nature is one option among several they are demonstrably capable of. Change, on this account, does not require becoming a different person. It requires bringing into the difficult setting the behaviour the person already manages elsewhere, which is a problem of practice, cues and attention rather than a problem of possibility. The argument also reframes what counts as evidence against change. Those who say people never change usually have in mind someone who behaved badly, promised to stop, and did it again. Proponents accept that such cases are common while denying what is inferred from them: a person who fails repeatedly is showing that this change, attempted this way, is hard, not that the species is incapable. The same person can usually be found behaving in exactly the desired manner in some other corner of their life, which is the strongest available evidence that the behaviour is within reach and that the difficulty lies in making it reach further.

Premises

Counter-arguments

Opponents reply that variation across settings is evidence of consistency, not flexibility: one underlying disposition expresses itself differently according to what each setting permits. A person who is charming to those who are useful and dismissive to those who are not is not displaying a repertoire that could be redirected; they are being perfectly consistent. On this view, producing the better behaviour where it is currently absent would mean changing what the person wants, which is the thing the argument assumes rather than shows.

Rejecting the premises

[Rejecting P1] Variation across settings is as much evidence of a stable disposition adapting to what each setting allows as of a flexible repertoire. The person who is warm to the powerful and cold to the powerless is behaving with complete consistency. [Rejecting P2] A repertoire can vary and still be fixed in the sense at issue. What varies is which of a person's responses the situation calls out, not the set of responses available to be called. [Rejecting C] Showing that a behaviour occurs somewhere in a life does not show it can be produced where it is wanted. It appears where the conditions suit the person, and the request is to produce it where they do not.