Much argument has been generated concerning the problem whether human deductive performance can best be viewed as rule-based (e.g. Rips) or model-based (e.g. Johnson-Laird). This paper argues that the distinction is ill-founded, and demonstrates that an ostensibly model-based syllogistic reasoning method can easily be implemented in a natural deduction calculus, which moreover makes fully explicit reference to the different possible interpretations of the premisses. More generally, it is unclear that other model-based methods cannot be given similar natural-deduction treatments, raising doubts about the distinguishability in principle of rule-based and model-based methods.
