“You can’t legislate morality.” This slogan is routinely invoked in our time to oppose government action to promote morality, from the posting of the Ten Commandments in a public school to enacting restrictions on abortion. The premise of the slogan is that law and morality are distinct, and moreover, that morality is not something that can be imposed by law.

That law and morality are distinct in some sense is simply a matter of common sense. There are things that are illegal (such as crossing the border from Mexico into the United States without the proper papers) that are not in themselves immoral. So, too, there are things that are immoral, such as lying or gluttony, that are not generally illegal.

But the doctrine,“You can’t legislate morality,” implies far more than the obvious notion that legality and morality are not always identical. Rather, the doctrine relies for its justification on the more fundamental conception that law and morality are inherently distinct. According to this view, most famously defended by John Stuart Mill, a liberal society should not advance any notion of the good life. Rather, it should merely promote safety and liberty, and only restrict free action to the degree that such action would infringe upon the freedom of others.

In reality, Mill’s doctrine is not neutral with regard to a philosophical conception of the good life. Rather, it advances one conception of the good (the classical liberal conception, in which safety and liberty are the most important values) over all others. Moreover, this classical liberal view, although routinely championed in theory, has never been seriously adopted in practice, even by self-proclaimed liberals.

Consider three ways in which we have successfully promoted paternalistic rules and laws that restrict individual action even though no one else’s security or freedom is threatened. First, we have laws that force people to use seat belts even though drivers and passengers who fail to use seat belts are endangering no one but themselves. Second, we have rules, aggressively promoted by schools and colleges, insisting that young people practice “safe sex.” Once again, couples who don’t use condoms or other birth control devices are only increasing their own chances of conceiving a baby or getting a sexually transmitted disease. Finally, we have increasingly repressive anti-smoking laws which limit smoking even where the risk to others is minimal.

Do these rules and laws amount to legislating morality? Of course they do. The only difference is that in the past people attempted rules that would preserve the life of the soul while today we have rules that seek to preserve the life of the body. In earlier times, society sought to promote virtuous action while today society seeks to promote physical health and longevity. Hygiene has replaced virtue as the main concern of our laws.

This brings us to the second concern of those who say that “You can’t legislate morality.” Are they right in holding that law is not an effective instrument in promoting morality? The answer to this question is: it depends on the law. Whether laws work—whether they achieve their goal—largely depends on the prudence of the legislation. Safe sex rules are going to reduce pregnancy and sexually transmitted disease to the degree that they are sensibly taught and implemented. Good laws, as Plato taught us, rely for their effectiveness on public consent. So it is with laws aimed at virtue, from drug laws to abortion restrictions. If they are sensibly crafted and win the consent of the governed, they are likely to work reasonably well.

There is room for a reasonable debate in society over differing conceptions of the good life, and over what rules are the most effective and prudent in making our society better. This debate is not advanced by mindless slogans that attempt to shut down this debate by declaring the whole subject off-limits. It is time, therefore, to jettison the meaningless slogan, “We can’t legislate morality,” because we can, we are, and we should.