There is a lack of knowledge about the diagnostic process in medical experts, and there is no clear consensus regarding its systematization in practice, teaching and evaluation. For the medical expert, clinical reasoning has become an ingrained form of thinking and is done "without realizing". The diagnostic process is a mental operation through which pathology is identified and the disease is evaluated. But the diagnosis is made by medical expert in a similar way as of the painter when he manages to highlight a figure on a background, when recognizing the edges by contrast, and so, only by observing colour in its context can you begin to understand its nature. For the family doctor, the same problem takes different forms according to its background. There are different diagnoses of the same symptom according to contexts. The professional intuition is sometimes marvellous and sometimes flawed. To map the boundary conditions that separate true intuitive skill from overconfident and biased impressions it should be based in the contextual evidence. The way to arrive at objective decisions is to contextualize. The complexity of family medicine lies in the contextualization of medical care in each patient.