TEST 1: MAKING FALSE PROMISES II
Kant’s answer is that promises would cease to mean anything. Thus we could never count on the promise of another, or could never be sure that a promise was serious and will be kept if ‘it is okay to make a false promise’ is a moral principle.
Accordingly, the maxim ‘it is okay to make a false promise,’ “as soon as it should be made a universal law, would necessarily destroy itself.”
Notice that there is no hypothetical which precedes the statement of the moral law ‘keep your promises,’ such as “if you want to be well-liked” or “if you want to have a good reputation” then keep your promises.