The recent turn to practices in international relations has been touted as a decisive step to provide a comprehensive theory of the field, comparable to the discovery of the “gluon” that revolutionized particle physics. More moderate arguments stress however that making the way we act the center of attention is preferable to having our research agenda set by methodological questions or metatheoretical issues, which gave the great theoretical debates in the field an often ethereal quality. This focus on international practices and the institutions to which they give rise promises to provide the “relevant” knowledge for decision makers as well as for the attentive public. Aside from the usual utilitarian considerations this, argument also calls attention to the fact that not everything that may be true is practically useful, feasible, or allowed. Those questions are of special importance in disciplines that deal with questions of praxis, where issues of the “should” and “ought,” of responsibility and commitment, weigh in heavily and which cannot be reduced to “what happens” by necessity, or “mostly”, or “frequently,” as evidenced by observations (made under ideal conditions, as in experiments, or by inductive inference from a big data set). To that extent it is somewhat surprising that this “turn” to practice bases its claims on its alleged ability to furnish us with a better theory and provide answers to what “really is”, as specified by the usual epistemological criteria accepted by the mainstream in political science. At the same time, this “turn” pays scant attention to the proprium of “action” that takes place in time and specific contingencies, under strategic conditions characterized by uncertainty (not only by “risk” where we at least must know or correctly guess the distribution of cases) and the possibility of genuine perspective-dissolving surprises (e.g., 9/11 or the fall of the wall in Berlin, or the financial meltdown). Action also frequently has detrimental consequences for others, or involves making choices for others (patients, clients, citizens), so shrugging off problems that impose special duties on actors is hardly possible. The perspective on the “observable,” or what “is,” which is supposed to disclose itself to an unengaged observer and can be used as a criterion for acting and for assessing the actions of others when vetted by the standards of a good theory, therefore seems to be highly problematic. Whatever we may believe and on whichever side we come down in the end, it is important to be aware of the various philosophical issues and conceptual difficulties that such an assessment requires. It cannot be short-circuited by simple “assumptions” (as “rational” as they might be), or by relying on dubious conceptual stretches, unexamined analogies, or the “kindness of strangers” in our networks.