Will the current wave of regional integration arrangements lead to the world being divided into competing inward-looking trading blocs? Or will it lead to a more open multilateral trading system? Using a multi-country political economy model, and after having shown that global free trade is optimal, the author investigates the possibility of achieving it through regionalism. An outsider country considering entering a trading bloc must weight the tradeoff between the costs of opening its own market to more foreign competition and the gains from getting better access to the bloc's preferential market. The gain of access is always larger, so an outsider would always want to apply for membership in the existing bloc. If the bloc policy is open membership, its expansion would result in global free trade. But if member countries can accept or reject new members, expansion of the bloc is unlikely to yield global free trade. When deciding whether to accept or reject new member, an insider compares the gains from getting preferential access to the new member's market with the losses from having to share its original preferential market with the new member. When the bloc is small, the gains are large enough to offset the losses, so insiders are willing to accept new members. As the bloc expands, the insiders'incentive for expanding decreases, eventually to zero. If only one regional integration arrangement were allowed to form, insiders would stop accepting new members when half the world belonged to the bloc. The remaining outsiders would probably form a bloc of their own, which would lead members of the original bloc to increase its size in anticipation of the creation of the second bloc. The threat of regionalism by outsiders would foster larger regional integration arrangements. In this model, the typical sub-game perfect equilibrium would be two blocs, one of them containing roughly two-thirds of the world, the other containing roughly one-third. Even if blocs form and merge simultaneously, yielding progressively larger symmetrical blocs, they would fail to converge in a single bloc unless the external tariff were low enough. In other words, global free trade could be achieved through bloc expansion if trading blocs lowered their external tariffs when abolishing their internal tariffs.
