Planning must be viewed as an incremental process that tests propositions about the most effective means of coping with social problems, reassessing and redefining both the problems and the components of development projects as more is learned about their complexities and about the economic, social, and political factors affecting the outcome of proposed courses of action. Complex social experiments can be partially guided but never fully controlled; thus, analysis and management procedures must be flexible and incremental, facilitating social interaction so that those groups most directly affected by a problem can search for and pursue mutually acceptable objectives. Rather than providing a blueprint for action, planning should facilitate continuous learning and interaction, allowing policy-makers and managers to readjust and modify programs and projects as they learn more about the conditions with which they are trying to cope.

Dennis A. Rondinelli (1993), Development Projects as Policy Experiments (New York: Routledge).

Make it 47 years old:

The term ‘implementation’ understates the complexity of the task of carrying out projects that are affected by a high degree of initial ignorance and uncertainty. Here ‘project implementation’ may often mean in fact a long voyage of discovery in the most varied domains, from technology to politics.

Albert O. Hirschman (1967), Development Projects Observed (Washington: The Brookings Institution).