Descartes' two errors: Reason and reflection in the great apes

This chapter examines reason and reflection in the great apes. It presents a variety of behavioural evidence that is best explained either by causal reasoning or by metacognition and analyses the between capacities for reasoning and for metacognition. It evaluates the results of a study which suggest that apes do not simply associate a cue with the presence of food, but understand that the food is the cause of the cue, and can reason accordingly. This behaviour can be regarded as evidence of a capacity for protological reasoning that relies on pairs of contraries and conditional dependence based on causal dependence.