Abstract：Happiness is a hot but controversial topic in the history of philosophy. The reason that these theories of happiness did not lead humans to achieve happiness is the unhappiness hazard in the foundation of their theories. This hazard can be generalized as the thought of “non-coexistence”, or more specifically the individualism and holism in methodology. Human is taken as a kind of social and relational existence, but co-existence precedes existence, which means only by building rational social relations can humans achieve true happiness. In fact, Marx constructed his view of happiness from a perspective of coexistence and surpassed the traditional thought of “non-coexistence”, making true happiness for all humans possible.

Keyword：Marx;co-existence;happiness;the thought of “non-coexistence”;individualism;holism;