The Quantitative Problem for Theories of Dysfunction and Disease

Many biological functions allow for grades. For example, secretion of a specific hormone in an organism can be on a higher or lower level, compared to the same organism at another occasion or compared to other organisms. What levels of functioning constitute instances of dysfunction; where should we draw the line? This is the quantitative problem for theories of dysfunction and disease. I aim to defend a version of biological theories of dysfunction to tackle this problem. However, I will also allow evaluative considerations to enter into a theory of disease. My argument is based on a distinction between a biological and a clinical perspective. Disease, according to my reasoning, is restricted to instances that fall within the boundaries of biological dysfunctions. Responding to the quantitative problem does not require arbitrary decisions or social value-judgements. Hence, I argue for a non-arbitrary, fact-based method to address the quantitative problem. Still, not all biological dysfunctions are instances of disease. Adding a clinical perspective allows us to prevent the potential over-inclusiveness of the biological perspective, because it restricts the boundaries of disease even further.