Freedom of speech is fundamental to a robust society, because it allows people to say what they think - to air ideas and grievances and debate them openly. Without it, many, many other rights and freedoms are vulnerable.
Freedom of speech is also a precarious thing, and too often we're too casual about constraints upon it. The law, in the form of draconian libel legislation, and the more recent culture of political correctness often push against and constrain this basic right in a free society.
Voltaire is usually credited with the most famous rallying cry for this freedom: "I disagree with what you say, but will defend to the death your right to say it." That's a pretty black and white formulation and it's often easier to defend in principle than in practice.
What, then, are we to make of Iris Robinson's recent and repeated comments about homosexuals, describing their practices as an 'abomination' before God?
Reaction to the Strangford MP's comments has been strong, and rightly so. Gay groups and wider society has condemned her for saying it, and the Royal College of Psychiatrists has publicly undermined her suggestion that homosexuality is some sort of condition that can be cured. The source for Mrs Robinson's view on the acceptability of gay people is the Bible. Specifically it is the Book of Leviticus that describes homosexuality as an abomination. That part of the Bible also advocates ritual sacrifice, slavery and the death penalty for fortune tellers.
That fact is that her views are vastly out of step with modern society. Homosexuality is a fact of life. We do not expect Mrs Robinson and her ilk to celebrate it by taking part in the Gay Pride festival, but Northern Ireland is a better place for openly acknowledging and accepting gay life, rather than trying to drive it underground.
The issue of civil partnerships — often referred to as 'gay marriage' — is settled, but for those who disagree with it, the advantages can be summed up thus: stable human relationships, of whatever sort, make stable societies.
Mrs Robinson's comments may cause some discomfort for her husband, the new First Minister. His office has funded, and presumably will continue to fund, the Gay Pride festival. Any withdrawal of that funding would expose his office to a lawsuit under equality legislation and we trust Mr Robinson will not expose the taxpayer to any more expensive tomfoolery by Government.
So should the MP be free to express her exasperatingly outmoded views? Voltaire says yes, but there is also a classic formulation about limitations of speech, courtesy of the American Supreme Court: freedom of speech does not mean the freedom to cry 'Fire' in a crowded theatre.
In other words, with the right comes responsibility not to abuse it — and that goes double for people in prominent public positions. Mrs Robinson is not responsible for thuggery, but the recent attack on a young gay man in Newtownabbey serves to highlight the need for care in public remarks. The MP has used her freedom, and we will also exercise ours: Mrs Robinson, you're wrong, and you're wrong to say it.