The minimal role of the higher categories in biology

Talk of higher categories (ranks) like Genus and Family is ubiquitous in biology. Yet there is widespread skepticism about these categories. We can locate the source of this skepticism in the lack of “robust concepts” for these categories, robust theories of what it is to be in a certain category. A common defense of category talk is that its virtues are “just pragmatic and not theoretic”. But this strains credulity. We should suppose rather that talk of the higher categories does theoretical work. What work? The paper proposes a “minimal concept” for a category, according to which the category is at least explanatory in marking out, in a rough and ready way , a level in the hierarchy of explanatory taxa. The skepticism is exaggerated.