nisms, for example, is highly dependent on attributes of the resource. Rarely can one find a successful pricing mechanism for irrigation water in a system without reliable storage. If the amount of water available cannot be calculated, few farmers are willing to pay a price for an unknown quantity of water. On the other hand, where dams have been constructed and reliable measures of water quantity exist, farmers have been willing to engage in weekly water markets for centuries (see, for example, Maass and Anderson, 1986). Knowledge about such causal linkages is essential for monitoring the functioning of resource management institutions and for deciding whether they need additional support.
Fourth, in order to craft an appropriate strategy for a situation, practitioners need a correct general understanding of the actors whose behavior the strategy is designed to influence. To act effectively, it is necessary to see events from the perspective of those acting in the situation. Only by doing so can a practitioner diagnose a changing situation accurately and select appropriate ways of communicating with and influencing others. Faulty understanding of others is a major source of miscalculations leading to major errors in policy, avoidable catastrophes, and missed opportunities.
All these types of knowledge are generic in that they apply across situations that have the same characteristics. It is important to emphasize, however, that although such knowledge is useful, even indispensable, a practitioner also needs accurate time and place knowledge to act effectively. Skilled practitioners use their judgment to combine generic and specific knowledge in order to act in what are always unique decision situations, each with its own historical trajectory and current resource and institutional characteristics. The contributors to this volume have attempted to develop the first three kinds of knowledge described: (1) general conceptual models of resource management situations, (2) knowledge about the conditions favoring the success of particular institutional forms, and (3) knowledge about the causal processes that lead them to succeed or fail. In doing this they have had to grapple with other important but difficult issues: defining success, setting reasonable expectations and timelines for evaluating success, identifying indicators of success, and deciding how to make general inferences when historical evidence is imperfect and when one can never know what the outcome would have been if practitioners had acted differently or if events beyond their control had played out differently.
Some writers (e.g., Ostrom, 1990) have translated generic knowledge into sets of institutional design principles: generic advice about properties that should be designed into institutions to increase their chances of long-term success. These include principles such as clearly defining the boundaries of a resource, matching provision and appropriation rules to local conditions, participation of users in making future policies, devising ways of monitoring, using graduated sanctions, providing conflict resolution mechanisms, and recognizing the right to organize. This is a useful translation of the research literature into policy guidance, if practitioners understand that the design principles are provisional and likely to need