ABSTRACT
The use of conditionals is central to human reasoning, and any psychological theory of reasoning worthy of the name must have an adequate account of conditionals in natural language. Yet even taking the first steps towards a theory of the ordinary indicative conditional immediately entangles the psychologist in formidable logical and philosophical, as well as psychological, problems. It is a good test of any psychological theory of reasoning to go straight to its account of ordinary indicative conditionals. The theory is in serious trouble if it does not have an adequate account of this conditional, and it is very easy to fail this test, as I will try to show in what follows. Further challenges are presented by counterfactual and deontic conditionals.
