Clinical reasoning is the process by which veterinary surgeons integrate a multitude of clinical and contextual factors to make decisions about the diagnoses, treatment options and prognoses of their patients. The brain utilises two methods to achieve this: type one and type two reasoning. Type one relies on shortcuts such as pattern-recognition and heuristics to deduce answers without involving working memory. Type two uses working memory to deliberately compute logical analyses. Both reasoning methods have sources of errors, and research has shown that diagnostic accuracy is increased when they are used together when problem-solving. Despite this, it appears unlikely that clinical reasoning ‘skill’ can be improved; instead, the most effective way to improve reasoning performance experimentally appears to be by increasing and rearranging knowledge. As yet, there is no evidence that overall clinical reasoning error can be reduced in practice.