Idiopathic means "without a known cause." My favorite source for definitions defines it as
adjective Pathology .
of unknown cause, as a disease.
And so, there's a clear link to medicine. But "unknown causes" aren't limited to this field, are they? And we have a whole segment of our industry devoted to identify causes; we call it "performance attribution."
Imagine what it would be like without these tools to properly evaluate and assess what causes the returns and excess returns our portfolios achieve. Without attribution, our results are idiopathic, since we cannot identify what caused them. Granted, one might guess, but without proper analysis the accuracy of the assessment is weak, at best.
Much of life is idiopathic, is it not? But in those areas, such as performance measurement, where we can perform the analysis, we should, as the value from these discoveries is great.