An explanandum (L.) is a sentence describing a phenomenon that is to be explained, and the explanans is the sentences adduced as explanations of that phenomenon. For example, one person may pose an explanandum by asking ‘why is there smoke?’, and another may provide an explanans by responding ‘because there is a fire’. In this example, ‘smoke’ is the explanandum, and ‘fire’ is the explanans.
As a siderbar, consider similar latinate terminology:
- Explicandum — that which gets explicated vs. Explicans — that which gives the explication
- Constitutum — that which gets made up, constituted vs. Constituens — that which makes it up, e.g. the constituents
- Definiendum — that which is being defined vs. Definiens — that which constitutes a definition