Uncertainty in Economics || TRANSACTION COSTS, RISK AVERSION, AND THE CHOICE OF CONTRACTUAL ARRANGEMENTS**This article is an excerpt from my manuscript, The Theory of Share Tenancy-With Special Application to Asian Agriculture and the First Phase of Taiwan Land Reform (to be published by The University of Chicago Press). For their helpful comments I am indebted to Armen A. Alchian, R. H. Coase, Harold Demsetz, Jack Hirshleifer, D. Gale Johnson, Harry G. Johnson, John McManus, Theodore W. Schultz, and George J. Stigler. Thanks for financial support are given to the Lilly Endowment grant supporting the Study of Property Rights and Behavior at the University of California at Los Angeles, and to the Ford Foundation grant for International Studi