This chapter takes on the nature of scientific activity, particularly in medicine, setting out to defend the "Systematicity Thesis," which posits that medicine, like science, is systematic inquiry. Referencing literature on the demarcation issue in philosophy of science, it maintains that despite the failure of established approaches, the issue should not be abandoned. Science, it suggests, is a family resemblance concept unified not by an intrinsic property but by a relational property that allows gradational differences from nonscientific pursuits. Using Hoyningen-Huene’s (2013) account of systematicity as a necessary criterion for science, the chapter shows that both medical science and clinical medicine meet this criterion. In a critical dialogue with Oreskes (2019), the thesis is applied and tested, demonstrating that homeopathy lacks the systematicity present in scientific pursuits, making it vulnerable to biases. It also underscores that systematicity fosters reasoning and inquiry that yield reliable knowledge and understanding.