Bain argues that if we hold the origin of the universe as equally mysterious against simple equations such as 3×4=12, it seems unimaginable what kind of concepts would be described as non-mysterious.
He provided many example relative pairs where the correlative terms find their meaning through contrast: rest-toil, knowledge-ignorance, silence-speech, and so on.
[9] Critics identify the fallacy in arguments for psychological egoism, which proposes that all actions conducted by individuals are motivated by their own self-interest.
Outside of this idea it is believed that sometimes people do things selflessly, such as acts of charitable giving or self-sacrifice.
Psychological egoism explains all scenarios entirely in terms of selfish motivations (e.g., that acting for one's own purposes is an act of self-interest); however, critics charge that in doing so they are redefining selfishness to the point where it encompasses all motivated actions and thus makes the term meaningless.