Immanuel Kant says that hypothetical imperatives are imperatives based on an "if" question. An example is, "If you wish to not die a hideous death, don't smoke". They are means to some end. We can choose to ignore this command if we wish - and many people do - but this means also rejecting the "if" on which the command rests. As beings with the ability to reason, we can arrive at a decision. The decision will vary from person to person, unlike a Categorical Imperative.