a1 Psychology Department, Durham University, Science Laboratories, South Road, Durham City DH1 3LE, United Kingdom. email@example.com
Barbey & Sloman (B&S) relegate the logical rule of the excluded middle to a footnote. But this logical rule is necessary for natural sampling. Making the rule explicit in a logical tree can make a problem easier to solve. Examples are given of uses of the rule that are non-constructive and not reducible to a domain-specific module.