How did Mill resolve tensions in Utilitarianism and Liberalism concerning the public/private distinction?

Question

J. S. Mill is well known as an intellectual father of both Utilitarianism and Liberalism, but I was thinking recently about a tension between these lines of thought and wondered if he ever addressed it. The tension is this, Utilitarianism leaves no boundary between ethics and politics. An action is good if it maximizes happiness, period. Politics, according to a Utilitarian, is just another means of happiness maximization. Liberalism, on the other hand, places a lot of importance on the distinction between public and private behavior and beliefs. So, for example, if I believe in God or not is no concern to others because it is a private belief, but if I rob my neighbor, I am liable to punishment, since this is a public act. However, if Utilitarianism erases the ethics/politics boundary, how can Liberalism keep the public/private boundary in tact?

The most straightforward answer to this question, one which I suppose Mill to have given, is that respecting a public/private boundary in our politics tends to maximize general happiness. After all, as Jefferson said, it neither breaks my leg nor picks my pocket if my neighbor has different religious beliefs. But if the state were seriously committed to happiness maximization, shouldn't the state be obliged to hinder the spread of religions that cause unhappiness? I suppose Mill would say that the marketplace of ideas will ensure that unhappy religions die out in the long run, but isn't that being a bit optimistic? Besides, as Keynes said, in the long run we're all dead. Shouldn't the government try to speed this process along?

So, my question is, does Mill ever make arguments for the public/private distinction that will hold even if it empirically turns out in certain cases that happiness could be maximized by violating this principle? Or were all his arguments for Liberalism empirically grounded? (Although, now that I think of it, you could say the same about any other 'right' guaranteed by liberalism, but I'm especially interested in the public/private distinction, since it is what separates Liberalism from totalitarianism.)

Answer 1

At the end of the second section of On Liberty, Mill gives a summary of the four reasons why there should be free speech:

First, if any opinion is compelled to silence, that opinion may, for aught we can certainly know, be true. To deny this is to assume our own infallibility.
Secondly, though the silenced opinion be an error, it may, and very commonly does, contain a portion of truth; and since the general or prevailing opinion on any subject is rarely or never the whole truth, it is only by the collision of adverse opinions that the remainder of the truth has any chance of being supplied.
Thirdly, even if the received opinion be not only true, but the whole truth; unless it is suffered to be, and actually is, vigorously and earnestly contested, it will, by most of those who receive it, be held in the manner of a prejudice, with little comprehension or feeling of its rational grounds. And not only this, but, fourthly, the meaning of the doctrine itself will be in danger of being lost, or enfeebled, and deprived of its vital effect on the character and conduct: the dogma becoming a mere formal profession, inefficacious for good, but cumbering the ground, and preventing the growth of any real and heartfelt conviction, from reason or personal experience.

I think you really need to understand what "utilitarianism" means to Mill. The caricature of utilitarianism as "the greatest good for the greatest number" is good as far as pithy sayings go, but it leaves a lot of complexity out. You might consider Mill's famous claim:

it is better to be a human being dissatisfied than a pig satisfied; better to be Socrates dissatisfied than a fool satisfied

He's obviously not interested in "happiness maximization" in a straightforward sense; Mill believed in a "hierarchy of pleasures" - i.e. certain types of happiness are better than others. So to Mill, the argument that free speech might decrease certain types of happiness would not be a conclusive argument against it - we might value the happiness which comes from exercising our rationality above that which comes from other things, so the tradeoff is worth it.

(This is, as you say in your comment, closer to what some deontologists believe than what some consequentialists believe.)