Richard Wollheim threatened George Dickie's institutional definition of art with a dilemma which entailed that the theory is either redundant or incomprehensible and useless. This article modifies the definition to avoid such criticism. First, it shows that the definition's concept of the artworld is not vague when understood as a conventional system of beliefs and practices. Then, based on Gaut's cluster theory, it provides an account of reasons artworld members have to confer the status of a candidate for appreciation. An (...) authorised member of an artworld has a good reason to confer the status on an object if it satisfies a subset of criteria respected as sufficient within this artworld. The first horn of the dilemma is averted because explaining the reasons behind conferral cannot eliminate references to the institution, and the second loses its sharpness, as accepting partial arbitrariness of the conferral does not deprive the theory of its explanatory power. (shrink)