This paper is an invited response to Kashdan, Biswas-Diener, & King (2008) and to Waterman's (2008) commentary. Kashdan et al. assert that the distinction between hedonic and eudaimonic well-being is unwarranted philosophically and scientifically. We disagree, because a correct understanding of Aristotle refutes Kashdan et al.'s claims, and we refute three specific claims made about the definition, measurements, and overlap of kinds of subjective well-being. We re-analyze data from Keyes' (2005b) paper on mental health, and find that nearly half (48.5%) of the MIDUS national sample has high hedonic well-being. However, only 18% are flourishing, which requires a high level of hedonic and eudaimonic well-being. The remaining 30.5% with high hedonic well-being but moderate eudaimonic well-being has nearly twice the rate of mental illness as flourishing individuals. Costs are incurred, we conclude, by science and citizens when we do not distinguish and achieve both kinds of well-being.
Keyes et al. (2009) studied this question.