This paper examines the complex research landscape of contemporary suicidology from a philosophy of science perspective. I begin by unpacking the methods, concepts, and assumptions of some of the prominent approaches to studying suicide causation, including psychological autopsy studies, epidemiological studies, biological studies, and qualitative studies. I then analyze the different ways these approaches partition the causes of suicide, with particular emphasis on the ways they conceptualize the domain of mental disorder. I argue that these different ways of partitioning the causal space and conceptualizing mental disorder result in incommensurabilities between the approaches. These incommensurabilities restrict the degrees to which the different approaches can be integrated, thus lending support to explanatory pluralism in the study of suicide causation. They also shed light on some of the philosophical underpinnings of the disagreement between mainstream suicidology and the emerging area of critical suicidology.