The contradiction in conception test is one of two tests posed by Kant’s Formula of the Law of Nature. This article proposes a new interpretation of this test: a causal-teleological version of the Logical Contradiction Interpretation. Its distinctive feature is that it identifies causal and teleological implications in the thought of a universal law of nature. A causal-teleological version of LCI has two advantages. While the established view of the Groundwork’s applications of the CC test is a hybrid view that (...) treats the Groundwork’s arguments as different in kind, a causal-teleological version of LCI unifies the Groundwork’s applications of the CC test. Relatedly, a causal-teleological version of LCI provides a solution to the problem of how the CC test can confirm the impermissibility of a self-directed maxim. (shrink)