Summary

There are clear theoretical and practical implications of the way people make inferences and decisions. In addition, there are a variety of very different developmental theories that attempt to model how the underlying competencies change over time. The starting point for these discussions is the well-documented tendency for people to make a combination of “logical” and “nonlogical” inferences and judgments. Logical inferences refer to conclusions that are logically valid, which are theoretically at least a product only of the syntactic structure of the components of the inference. Nonlogical inferences are inferences that reflect personal knowledge and/or individual biases, and that produce conclusions that are not necessarily valid. Scientific and mathematical disciplines rely on the use of logically valid inferences, and the existence of strong tendencies towards making nonlogical inferences has clear educational implications. One of the most common ways of understanding the interplay between these two forms of inference are general dual process frameworks, which postulates the coexistence of two systems of making inferences, a heuristic and an analytic system, that function very differently and can produce different responses to the same problem. The analytic system is generally considered to be responsible for the potential to make logically valid inferences. However, there are a variety of developmental theories that provide different approaches to how logical reasoning may develop. The key concepts for each theory are very different, and it is important to understand how these differences can be articulated, in the light of the key empirical results. Finally, each of these different approaches has very different educational implications.