A coherentist conception of ad hoc hypotheses

What does it mean for a hypothesis to be ad hoc? One prominent account has it that ad hoc hypotheses have no independent empirical support. Others have viewed ad hoc judgements as stemming from a lack of unifiedness of the amended theory. Still others view them as merely subjective. Here I critically review these views and defend my own Coherentist Conception of Ad hocness by working out its conceptual and descriptive attractions.