Abstract Part of the business of argumentation theory involves resolving a conceptual dispute over what argumentation and argument are in the first place. This dispute has produced various “concepts of argument.” The goal of this paper is twofold: (1) to develop a complete ontology of argumentative phenomena, capable of accounting for various conceptions of argument—something, as I argue, that is badly wanting in argumentation theory; and, within this ontology, (2) to defend a position that there is but one concept of argument needed to grasp these diverse phenomena and conceptions of argument and argumentation. I move in four steps. First, I briefly sketch the discussion over arguments-as-activities and arguments-as-products. Second, I go back to the classic work of Twardowski on actions and products and adapt it for argumentation theory, producing a complex yet systematically organized conceptual ontology of argument and argumentation. This conceptual housekeeping allows me, third, to critically engage some of the recent, Frege-inspired philosophical literature on the concept of argument, while defending act-based approaches to argument(ation). Fourth, I present a positive proposal of a minimal, contrastivist concept of argument as a set of reasons advanced to support a conclusion C 1 rather than another conclusion C n .

I consider Sally Jackson's analysis of ''black box arguments,'' on the most abstract level, as a valuable contribution to an ongoing discussion on a very important issue: how to find a rational and critical way between the two extremes of, on the one hand, uncompromising dogmatism and, on the other, endless scepticism in our deliberations. Philosophers of science and argumentation theorists alike have persistently been trying to properly diagnose and solve this difficulty central to their disciplines. Therefore, those of the tentative conclusions of an open, transparent box of 'science in action' which are based on reliable methods and compelling evidence cease to be controversial and become widely accepted through a consensus of a community of scientists. In this way, a contested hypothesis turns into an accepted result, which serves as a black box device-its inner workings are no longer open to scrutiny, and the only thing we can do is to 'input' questions and obtain authoritative 'output' answers.