Unpacking underdetermination: Theoretical challenges in understanding macroecological and biogeographic patterns

Macroecology and biogeography have made significant strides in understanding the patterns and processes underlying biodiversity, yet the problem of underdetermination (the Duhem–Quine thesis) remains an ongoing challenge. Underdetermination arises when multiple explanations are consistent with the observed data, resulting in challenges in theory and model development and testing. Here, we explore the different forms of underdetermination in macroecology and biogeography and their implications for understanding biodiversity patterns. We highlight the gradient ranging from optimistic to pessimistic views in addressing the problem, coupled then with realistic and instrumentalist scientific reasonings, illustrating these issues by evaluating how underdetermination may affect our understanding of the latitudinal diversity gradient. We show how evolution and diversification introduce a new and unexpected source of underdetermination, and that unpacking the underdetermination problem in macroecology and biogeography requires deconstruction methods in a more comprehensive and integrated approach that considers both hierarchical scale and phylogenetic relationships between organisms and trait‐based explanations.