Reply to Betts et al. “When are hypotheses useful in ecology and conservation?”Meredith Root-Bernstein1, 2, 3UMR CESCO, CNRS, Muséum National d’Histoire Naturelle, Paris, FranceCenter of Applied Ecology and Sustainability, Santiago, ChileInstitute of Ecology and Biodiversity, Santiago, ChileWords: 2045It is difficult to disagree with Betts et al. (2021) when they claim that hypotheses are often useful but sometimes not necessary. The difficulty with Betts et al. does not lie with any of their individual points, but rather with the lack of a clear argument giving them structure. This is not just a critique of style. It is relevant because it is an example of what I think is the real problem in ecological research. In my view, the lack of hypotheses in ecology and conservation is not just about the rise of big data approaches, or the documentation of applied work. More generally, I argue that the low use of hypotheses reflects the failure of ecology and conservation to value and develop discipline-specific forms of argument, logic and reasoning. I first address the particular nature of the hypothesis as an argument form, and then the question of whether there are specifically ecological argument forms. Finally I argue that we need a broad set of arguments and logics suitable to the broad set of phenomona in ecology, and that hypotheses are usually derived from non-hypothetico-deductive reasoning and logic. If we want more or better hypotheses, we need more and better forms of non-hypothetico-deductive ecological reasoning.A hypothesis is a form of argument structured so that it can be answered in only one of two ways: rejection or non-rejection. Hypotheses are also characterized by particular ways of framing questions that are considered legitimate, interesting, or elegant, which varies by the discipline or subject matter. I will illustrate my points about the need for forms of argument that fit a subject matter with the Betts et al. paper itself. Betts et al. present their argument about why ecologists should use hypotheses in the form of a couple of hypotheses, the predictions of which they test in a hypothetico-deductive manner on quantitative data using statistical reasoning. They structure their hypothesis as though it were an evolutionary argument: they identify potential discrete individual benefits of adopting a behaviour within a specific environment.