A Note on Loadings and Deductibles: Can a Vicious Circle Arise?

In a recently reprinted paper Borch wonders whether an increase in insurance loadings, together with the consequent increase in customers' deductibles, may be the start of a vicious circle, in which higher deductibles produce higher loadings and vice versa, ad infinitum. This paper rules out the possibility of a vicious circle, in a model à la Borch. First of all, increases in costs of the type considered by Borch are not necessarily followed by increases in loadings. Second, increases in loadings are not necessarily followed by increases in deductibles, since in equilibrium insurance may be Giffen. Last but not least, loadings do not increase with deductibles, because the only viable equilibrium is a Stackelberg one.