Well, in some sense, obviously, you can identify as whatever you please. But it’s a rare identity that carries no implications about the world or at least how you react to it. To run with the example, I expect there are a number of imperfectly correlated reasons you might call yourself a Manchester United fan: you might for example feel more excited—a physical, measurable response—when watching ManU games than games ManU isn’t involved in, or you might be involved with the club’s fan community. Generally, however, these are going to be statements about the state of the world, not purely arbitrary stances.
To the extent that it makes sense to talk about the legitimacy of an identity, it might be said to refer to how closely that identity maps to these evidences. That’s not to say that a good litmus test exists in every particular case, though.
Well, in some sense, obviously, you can identify as whatever you please. But it’s a rare identity that carries no implications about the world or at least how you react to it. To run with the example, I expect there are a number of imperfectly correlated reasons you might call yourself a Manchester United fan: you might for example feel more excited—a physical, measurable response—when watching ManU games than games ManU isn’t involved in, or you might be involved with the club’s fan community. Generally, however, these are going to be statements about the state of the world, not purely arbitrary stances.
To the extent that it makes sense to talk about the legitimacy of an identity, it might be said to refer to how closely that identity maps to these evidences. That’s not to say that a good litmus test exists in every particular case, though.