The Nature of Mechanistic Reasoning in Chemistry

Mechanistic reasoning is used in chemistry to build arguments, generate explanations, and make and justify predictions about the properties and behavior of material substances. Although mechanistic reasoning in chemistry shares fundamental features with its manifestations in other domains, recognizing its distinctive characteristics is crucial for advancing chemistry education in this area. In chemistry, mechanistic reasoning generates causal stories involving entities spanning various levels of granularity and characterized by properties whose underlying mechanisms may be encapsulated. These stories rely on diverse symbolic and iconic representations that explicitly and implicitly communicate qualitative and quantitative information about relevant components and their interactions in a system. Additionally, chemists often combine model-based, case-based, and rule-based approaches to reasoning when generating such causal stories. The central goal of this contribution is to unpack the complexity of mechanistic reasoning in chemistry to identify and highlight the challenges that chemistry students may face to reason mechanistically in the discipline and describe the types of supports that can help foster their learning.