The assumptions of Jacob Viner's theory of customs unions

The paper starts by presenting a method for the decomposition of the impact of a customs union into the familiar trade-diversion, trade-creation and consumption effects. This is used as a framework within which Viner's original customs-union analysis is investigated. The issues examined are whether Viner's analysis indeed makes the assumptions about production and consumption which are attributed to it by conventional wisdom; whether the assumptions Viner did make were consistent; and the possible explanations of Viner's analytical course. The investigation is supported by references to Viner's analytic contributions beyond the sphere of customs unions.