Only recently have economists begun to face up seriously to the prob- lem of the cost of capital cum risk. In the process they have found their interests and endeavors mergingwith those of the finance specialist and the managerialeconomist who have lived with the problem longer and more intimately. In this joint search to establish the principles which govern rational investment and financial policy in a world of uncer- tainty two main lines of attack can be discerned. These lines represent, in effect, attempts to extrapolate to the world of uncertainty each of the two criteria-profit maximization and market value maximization- which were seen to have equivalent implications in the special case of certainty. With the recognitionof uncertainty this equivalencevanishes. In fact, the profit maximization criterionis no longer even well defined.
Under uncertainty there correspondsto each decision of the firm not a unique profit outcome, but a plurality of mutually exclusive outcomes which can at best be describedby a subjective probability distribution. The profit outcome, in short, has become a randomvariableand as such its maximization no longer has an operational meaning. Nor can this difficulty generally be disposed of by using the mathematical expecta- tion of profits as the variable to be maximized. For decisions which affect the expected value will also tend to affect the dispersionand other characteristicsof the distributionof outcomes. In particular,the use of debt rather than equity funds to finance a given venture may well in- crease the expected return to the owners, but only at the cost of in- creaseddispersionof the outcomes.