Among the ideas that stayed with me from my applied psychology student days are those I encountered and formed through discussions that sought to distinguish the "normal" from the "pathological." It's one of those philosophical problems without a definitive solution—like i believe all important philosophical (or human) problems are.
I remember two French thinkers in particular, though from different generations. The first is Émile Durkheim, one of sociology's giants, who lived from the second half of the 19th century into the early decades of the 20th. Durkheim left us with the idea that in society, crime is "normal, necessary, and useful." Without crime, a society would have no way to evolve its morals, laws, and rules. To support this postulate, he argued that pain and suffering are often viewed as signs of disease despite the existence of serious painless pathologies. Conversely, some medically insignificant conditions cause extreme pain, and in other cases, the absence of pain or the presence of pleasure can be symptoms of illness. For Durkheim, disease might even represent a phase of adaptation to changing external conditions. The pathological state, therefore, can be useful in some cases. When we're vaccinated, for instance, we inject a small "quantity of disease" so our bodies become capable of fighting it, yet this isn't abnormal since getting vaccinated is part of normality (at least for some, or in its statistical sense).
The second French thinker is Georges Canguilhem, a physician and philosopher born in the early 20th century. He was a schoolmate of Sartre and doctoral advisor to Michel Foucault—thinkers who surpassed him in notoriety. Canguilhem was also a rebel and activist, participating in various pacifist movements, counter-power initiatives, and even the Resistance during World War II. He defended his doctoral thesis in Medicine on "The Normal and the Pathological." Following Durkheim's line of thought, he advocated that "pathology is part of normality"; that pathology exists within normality and normality within pathology. Do you know anyone who has never been sick? Being sick occasionally is part of normality. The plot thickens when disease becomes normality. It's normal to have muscle pain after an intense exercise session. It wouldn't be normal if that same pain persisted for weeks, months, or years. The longer the pain lasts, the more likely you are to become accustomed to living in that state, leading to another state: resignation.
