The function of the heart is historically contingent

Some philosophers of medicine argue that there are objective facts about the biological function of organs, and that these facts are used to objectively define diseases. The function of the heart is taken to be particularly obvious and well established. Contrary to this, I argue that the function of the heart is not fixed by nature, but rather that it is historically contingent. The disease heart failure results from the dysfunction of the heart. In opposition to the common-sense intuitions of philosophers, medics do not define heart failure simply as a reduced cardiac output, and up to half of patients with heart failure have a normal cardiac output. The present day medical definition of heart failure is thus counter-intuitive. In the early twentieth century, however, medics did define heart failure as a reduced cardiac output. This view was opposed in the 1930s, when a similar definition of heart failure to the one used today was put forward. I look closely at this historical episode, in order to explore the reasons for this development. I use this history to argue that present day knowledge of heart failure is not the inevitable result of careful observation of patients, but rather is historically contingent.