Can monkeys reason? Many studies have shown a simple use of logic by many monkey species in that they will select a cup that has been shown to have a treat or sounds like it has a treat (inclusion), and they can use exclusion to guess when a cup does not appear to have a treat or has a noiseless sound, that the other cup must have the treat. Still, researchers have argued that the monkeys who select well may not use logic, but rather are just avoiding an empty cup and seeking reward (approach/avoidance hypothesis). We tested these ideas both with visual and auditory presence and absence cues when 2 cups were used, and we complicated things by increasing the number of cups to 4, using a barrier to block 2 of the cups from a trial, and offering 1 or 2 cues of inclusion or exclusion. The result? The monkey data fit predicted logical outcome probabilities better than simply eliminating empty cups and/or guessing. We are in the revision stages of trying to publish these data now (2022).