Spanish translation here 
Paternalism means treating people like children. Children lack the maturity and wisdom to make their own decisions. Thus they need parents — or people playing the paternal role — to tell them what to do and, on occasion, to force them to do it.
Most people have no problem with paternalism when dealing with actual children, as well as the retarded, the senile, and the insane. But normal adults bristle at paternalism, even though we all act like children from time to time. Paternalism, they think, is incompatible with freedom.
I wish to argue, however, that there is no conflict between paternalism and freedom, provided that both terms are properly understood.
First of all, real paternalism has to be “for your own good,” i.e., in the actual interest of its object. People might claim to be abridging the liberty of others to help them, when in reality they are concerned to benefit only themselves. But that is fake rather than real paternalism. Real paternalism must be in the interest of its objects. Real paternalism is a kindness. Fake paternalism is merely a crime.
Second, there are true and false forms of freedom as well. Most people will agree that freedom is doing what you want to do. But what do we want to do? On this matter, I follow Plato and Aristotle, who argued that we all want basically one thing: the good life, happiness, self-actualization, or well-being (eudaimonia). That is the ultimate aim of every particular action. Every choice, whether we know it or not, is made in pursuit of the good life as we see it.
Thus if freedom is doing what we really want, and we all really want a good life, then living a good life is freedom. This implies that if we choose to do things that are not conducive to the good life, we are not acting freely, for doing things we don’t really want to do is unfreedom.
In other words, not every voluntary act is a free one. We are free when we pursue the good life (what we really want). We are unfree when we fail to pursue the good life (which we don’t really want to do).
There are two basic causes of unfreedom. First, there is ignorance of what is really conducive to happiness. We might think that smoking 20 cigarettes a day will make us happy, but it won’t. Second, there are occasions when we know perfectly well what will make us happy but we fail to do it because we are overcome by our emotions. We fear doing the right thing, or we find doing the wrong thing too pleasurable to resist.
We might choose to act out of ignorance or passion. We might even feel free when doing so. But if such actions are not conducive to the good life, they are not free, they are a form of bondage. Paternalism, therefore, can restore freedom by forcing us to stop throwing away our happiness out of ignorance or passion. Since freedom is doing what we really want, and we can be forced back onto that path, man can be forced to be free, as Jean-Jacques Rousseau put it so memorably.
This means that libertarianism, which claims that freedom is incompatible with paternalism, and that force is always the opposite of freedom, is simply wrong. If you really care about freedom, then the state should, in principle, have the power to paternalistically intervene when people are throwing away their freedom out of lack of knowledge or excess of feeling. One can debate the grounds and scope of such paternalistic interventions. But the principle is clear: paternalism is not an enemy of real freedom but one of its necessary guardians.