(Moral) philosophy and (moral) theology can function as (behavioural) science: a methodological framework for interdisciplinary research

In this paper I present two examples in which environmental moral rules, obtained from religious precepts (e.g., the dignity of non-humans and harmony with nature in Hinduism or Buddhism, stewardship in Judaism, trusteeship and parsimony in Islam, love of neighbours in Christianity) or ethical principles (e.g., responsibility for nature, responsibility for future and current generations, and aversion to inter- and intra-generational inequality) can be matched with observed behaviours to test assumptions, insights, or both. In particular, traditional scientific tests (i.e., validation vs. calibration for reliability; out-of-sample estimations vs. numerical simulations for feasibility) and recent scientific tests (i.e., invariance under observations vs. interventions for robustness of relationships; holism vs. individualism for aggregation requirements; and causal mechanisms vs. evolutionary processes for stability of equilibria) are applied to these examples to demonstrate how moral philosophy and theology (respectively) can function as instances of empirical behavioural science (i.e., by assessing observed actions in real contexts using scientifically sound procedures). Thus, this paper provides a standardised methodology for problem-solving contexts (i.e., achieving local and global sustainability) and knowledge-practicing contexts (i.e., testing the empirical content of moral rules) to support interdisciplinary research by integrating concepts and cross-validating models from different fields of inquiry. © 2019, Springer Nature B.V.