 According to Merriam-Webster’s Collegiate  Dictionary,[2]  something is ‘ad hoc’ if it is ‘formed or used for specific or immediate problems or needs’. An ad hoc hypothesis then is one formed to address a specific problem—such as the problem of immunizing a particular theory from falsification by anomalous data (and thereby accommodating that data). Consequently what makes a hypothesis ad hoc, in the ordinary English sense of the term, has nothing to do with the content of the hypothesis but simply with the motivation of the scientist who proposes it—and it is unclear why there would be anything suspicious about such a motivation. Nonetheless, ad hoc hypotheses have long been suspect in discussions of scientific method, a suspicion that resonates with the predictivist’s skepticism about accommodation. 