In social psychology justification is the process of socially accounting for ones beliefs or actions.
It is a process which is susceptible to being shaped by psychological factors.
((Main|self justification}} When accounting for ones action in our own minds the defence mechanisms can shape our accounts to ourselves. So for example we may deny our 'true' motivation if it is too shameful. While the processes of cognitive dissonance may lead us to distort our account with rationalization