ABSTRACT
It is far from trivial to find out what the controversy between the mental models and mental-logic ways to explain human reasoning is really about and what data could settle it. One way to make progress is to concentrate on a small domain that both theories address, and thoroughly examine which theory seems to be more likely to capture human reasoning. In the past, this approach could be only speculative, because where a mentalmodel theory of one domain existed, no mental-logic counterpart did, and vice versa. Recently it has become possible actually to compare both approaches on the domain of propositional reasoning. It is, therefore, not without interest to find out what exactly is at issue, what exactly the data say, and what exactly the respective theories can do to account for them.
