 In short, philosophical “theories of happiness” can be about either of at least two different things: well-being, or a state of  mind.[2]  Accordingly, there are essentially two bodies of philosophical literature about “happiness” and two sets of debates about its nature, though writers often fail to distinguish them. Such failures have generated much confusion, sometimes yielding bogus disagreements that prove to be merely  verbal.[3]  For instance, some psychologists identify “happiness” with attitudes of life satisfaction while remaining neutral on questions of value, or whether Bentham, Mill, Aristotle, or any other thinker about the good life was correct. Such researchers employ the term in the psychological sense. Yet it is sometimes objected against such claims that life satisfaction cannot suffice for “happiness” because other things, like achievement or knowledge, matter for human well-being. The objectors are confused: their opponents have made no claims about well-being at all, and the two “sides,” as it were, are simply using ‘happiness’ to talk about different things. One might just as sensibly object to an economist’s tract on “banks” that it has nothing to say about rivers and streams.