"Recall learning to drive a car, when you actually did have to think through what you were doing: "Depress clutch... OK, bring up slowly while releasing handbrake and depressing gas pedal slightly... look in mirror..."
My point is that a field of knowledge can endure a "crisis of foundations," in which the most fundamental issues are opened up for inquiry and deconstruction, without causing any permanent harm to the field.
I would push even further and assert that any field of knowledge which doesn't regularly experience such crises is stagnant.
