Tautology implies that the definition we give is redundant, but none of these things were defined in this way. This is because none of the research relies on th

Tautology implies that the definition we give is redundant, but none of these things were defined in this way. This is because none of the research relies on this kind of dictionary definition. Instead, they literally ask people hundreds of questions of the type: "To what extent would you consider yourself to be [adjective]?" (0 - 'not at all' to 5 - 'complete') Then they factor analyze the results to see which adjectives tend to be highly related to each other. Factor analysis builds on correlation to find shared variation among large groups of indicator variables. So it is related to how people think of the adjectives and what they mean, but it is not the case that we are just lumping definitions together or "saying the same thing in different words" in the way of a tautology. Instead, what we're saying is that "Most of these personality adjectives mostly mean the same thing. Here's the thing they all mostly mean. If humans in all languages have tons of words that mostly mean this common thing, maybe this common thing is significant and worthy of study." Regarding life satisfaction, the sense that one finds their life satisfactory and "would change nothing" (one of the items in the Satisfaction with Life Scale that was most likely used to measure it) doesn't show up in those other traits in any major way. In fact, to the extent that a description of the self is related to a world-view, belief or other external factor, it will never be a tautology, because a self-view and other-view or world-view will never share a common definition or tautology by virtue of the self-other distinction.