The reasoning supporting the conclusion that we need praxeology to determine policy is traced in detail below. We begin with the assumption that we need to determine what policy should be pursued.

1. We need to determine what policy will have objective value to humans (given).
2. Policy that has objective value to humans must have beneficial effects on their lives (by definition of objective value).
3. Therefore we need to determine policy that will have beneficial effects on human lives (by (1) and (2)).
4. Clearly, in order to determine policy that will have beneficial effects on human lives, we must be able to understand a proposed policy's general effects on human life.
5. Therefore we need to determine that policy's general effects on human life (by (3) and (4)).
6. Clearly, in order to determine a policy's general effects on human life, we must determine in particular how that policy will affect human action.
7. Therefore we need to determine how the policy will affect human action (by (5) and (6)).
8. Evidently, in order to determine how a policy will affect human action, we need to understand the general principles governing human action.
9. Therefore we need to understand the general principles governing human action—i. e., praxeology (by (7) and (8)).