Natural theology and natural law › Why application needs judgment

Question 94, article 4, distinguishes general principles from particular conclusions in contingent circumstances. Aquinas's example concerns returning entrusted goods. Returning them is generally right, but he considers a case in which someone demands them for use against the community. The circumstances can make what is generally required unreasonable in that case.

The example shows why knowing a general precept does not eliminate deliberation. One must understand what the action would do in its circumstances. This does not mean that a convenient exception cancels every inconvenient obligation; it means that a practical conclusion needs the conditions that make it appropriate.

The discussion also separates whether a conclusion is right from whether people recognize it. Aquinas allows error through such influences as passion and bad habit. Common rational principles therefore do not entail uniform agreement about every detailed moral question.

These distinctions matter when applying the theory to law. A statute may require a common determination among several reasonable alternatives. Another statute may conflict with the good it should serve. Treating every legal disagreement as an obvious violation of natural law would ignore the need to justify the particular conclusion.