One of the ideological foundations of the modern welfare states is the belief that people can be made happier by providing them with better living conditions. This belief is challenged by the theory that happiness is a fixed trait, rather than a variable state. This theory figures both at the individual level and at the societal level. The individual level variant depicts happiness as an aspect of personal character; rooted in inborn temperament or acquired disposition. The societal variant sees happiness as a matter of national character; embedded in shared values and beliefs. Both variants imply that a better society makes no happier people. Happiness can be regarded as a trait if it meets three criteria: (1) temporal stability, (2) cross-situational consistency, and (3) inner causation. This paper checks whether that is, indeed, the case. The theory that happiness is a personal-character-trait is tested in a (meta) analysis of longitudinal studies. The results are: (1) Happiness is quite stable on the short term, but not in the long run, neither relatively nor absolutely. (2) Happiness is not insensitive to fortune or adversity. (3) Happiness is not entirely built-in: its genetic basis is at best modest and psychological factors explain only part of its variance. The theory that happiness is a national-character-trait is tested in an analysis of differences in average happiness between nations. The results point in the same direction: (1) Though generally fairly stable over the last decades, nation-happiness has changed profoundly in some cases, both absolutely and relatively. (2) Average happiness in nations is clearly not independent of living conditions. The better the conditions in a country, the happier its citizens. (3) The differences cannot be explained by a collective outlook on life. It is concluded that happiness is no immutable trait. There is thus still sense in striving for greater happiness for a greater number.
