A memorial lecture is one of the ways we honour our debt to the past and discharge our responsibilities to the future.

Father Greg Jordan thoroughly deserves a lecture series: a former rector of St Ignatius’ College in Sydney, and of Jesuit-run university colleges in Hobart and here in Brisbane; a one-time parish priest at Toowong, chaplain to the Australian Catholic Students Federation, advocate for the traditional mass, and exorcist for the Archdiocese of Brisbane; he befriended hundreds, he taught thousands, and he touched the lives of tens of thousands.

This is our tribute to him and our acknowledgment of the impact he’s had on us. It’s our way to ensure that his voice is not stilled and his example not forgotten.

Father Jordan was a Catholic priest of a type once relatively common and now widely missed: learned yet gregarious; worldly yet Godly; humble in himself yet immensely proud of the order and of the Church; focussed on the life to come yet expert in the life we have. He was a priest of consequence; a man of God who mattered in this vale of tears.

He was a strong, genial and occasionally quirky presence as head of Riverview between 1968 and 1973, when I was in year ten. He physically rebuilt the school. He was often in the media urging governments of the day to give a better deal to Catholic and independent schools. On Saturdays, he made a point of driving his Mazda to just about every team event but he often lingered in the car, rather than on the sidelines, listening to the Goon Show.

At least for tonight’s purposes, his principal characteristic was indefatigable advocacy for the things he believed in: in God, in the Jesuits, in the Church and in a society which allowed believers to flourish and was immeasurably the better for it.

Had he been with us over the past few months, he would have been especially vocal about the attempt by the Tasmanian human rights lobby to persecute Hobart’s Archbishop Porteous for a very mild defence of traditional marriage that was circulated to Catholic schools and parishes. It would have made him more determined than ever to affirm the true teaching of the Church and the true wisdom of humanity – and also, I suspect, rather excited at the prospect of being officially harassed by politically correct thought police as a kind of modern day martyr. He wouldn’t have complained about them so much as dared them to do their worst.

Tonight, I’ve been asked tonight to address the subject of free speech.

You might be expecting a “mea culpa”. After all, I was the opposition leader who promised to “repeal in its current form” section 18c of the Racial Discrimination Act that outlaws what might “offend, insult, humiliate or intimidate” a person on grounds of race. There are similar acts in some of the states that outlaw offending, insulting, humiliating or intimidating a person on grounds of religion too.

Subsequently, I was the prime minister who bowed to the criticism of Liberal premiers, the ferocious attacks of the ethnic lobby, and the threat of my own colleagues to cross the floor to decide that the philosophical gain of changing section 18c wasn’t worth the political pain; only then to face the wrath of conservatives, who’d previously said next-to-nothing, for abandoning this particular election promise.

The right to free speech – like the rights to freedom of movement, freedom of association and freedom to amass property – is absolutely fundamental to a free society.

It’s so fundamental that Australians tend to take it for granted yet there are significant limits on it and they are becoming worse.

There’s this attack in Tasmania on the Church’s right to promote its own doctrine. Earlier, there was the notorious prosecution of the conservative commentator Andrew Bolt for questioning who might appropriately identify as “aboriginal”. The conservative broadcaster Alan Jones has been hauled before the regulator for heretical views about climate change. Earlier, in 2000, the conservative writer Tom Switzer was unsuccessfully prosecuted for linking Palestinians with terrorism.

The former Gillard government launched a witch hunt against News Ltd here in Australia – which had taken a strong editorial line against it – on the basis of errors by Rupert Murdoch’s UK papers; and proposed a new and more intrusive body to set media standards.

Then there are less overtly-political-curbs on free speech such as banning smoking ads and alcohol ads, requiring plain paper packaging of cigarettes, and prohibiting developer donations to political parties – on top of the limits traditionally (and much more reasonably) imposed by defamation laws and the requirements of public safety.

In principle, I support none of these recent restrictions on free speech. Why should tobacco sellers be banned from branding their packets, especially if they’re also required to carry a graphic health warning; why should developers be stopped from donating to political parties, especially when their donations are disclosed; and why should people expect never to be offended, especially when they have a right to reply to anything they don’t like?

Still, I haven’t noticed the main victims of these intrusive laws, the Bolts, the Jones or the Switzers, being intimidated into changing their mind or being persecuted into keeping quiet.

There’s no doubt that these are bad laws – but they only stand because they don’t actually work. So far, at least, their victims haven’t been silenced and important debates haven’t been suppressed.

In opposition, John Howard opposed the Keating government’s objectionable changes to section 18c; but, in government, he made no effort to repeal them, presumably because they weren’t actually doing much harm.

Of course, section 18c is a bad law. The question is how much effort should be expended trying to repeal it when there are other political fights that might be at least as important or easier to win.

In retrospect, I should have proposed a much simpler amendment and I should have persisted with it, along the lines of Senator Day’s subsequent proposal simply to drop “offend” and “insult” from the prohibitions, even if it had little chance of passing through the parliament.

Yes, the Abbott government could have handled the section 18c debate better but there’s a bigger imperative here.

By all means let’s make the case for fewer restrictions on free speech but let’s not substitute that for the debate we need to prosecute in support of values and institutions that have stood the test of time.

My point tonight, though, is less to defend free speech than to urge good people to exercise it because any “silent majority” that fails to justify itself will soon become a minority. It might be just a noisy minority at the start; it might be clearly a silent majority at the start but that’s not how it will finish if good people fail to find their voice.

It’s not fear of a knock on the door from the one of the human rights agencies that’s inhibiting the case for marriage between a man and a woman; it’s people’s reluctance to put the case and risk the accusation that they’ve been brain-washed by the Church. Indeed, the issue may be less a majority cowed into silence on traditional values but a collapse of belief in them.

Western Civilisation has been based on two fundamental precepts: first, that every human being deserves respect; and second, that we should treat others as we would be treated. An earlier formulation might have been that we are all made “in the image and likeness of God”; and should therefore “love our neighbour as we love ourselves”.

From these precepts flow the defining characteristics of Western Civilisation: freedom under the law; rights shaped by democratic institutions; and public and private benevolence. The right to question, to criticise and to speculate has been central to the development of our liberty, our security, and our prosperity.

Of necessity, speech that is free might very well be offensive, insulting, humiliating, and even intimidating but that’s the price of freedom. Speech can hardly be free if freedom is only for the speech we agree with. Without a vigorous argument about climate change, about aboriginality or about same sex marriage, for instance, how could we ever deepen our understanding of these issues or change our minds on them?

More than anything else, this openness to question and criticism has distinguished Western Civilisation from alternatives and given it an unequalled appeal, adaptability and capacity for growth. It’s also fostered an impatience with tradition and a readiness, perhaps, to throw out the baby with the bathwater or to take a good idea too far.

Some of the institutions and the values that have most helped to shape and to define Western Civilisation – Christianity, the Church and the Crown – now tend to be those most frequently under fire. At issue is the extent to which these institutions and values can adapt and thrive in current circumstances or seem irredeemably trapped in times past.

A generation ago, for instance, the challenge to the Church was the proposition that homosexuality was a fact of life and that “sin” should not be proscribed by law. Today, the challenge to the Church is the proposition that same sex marriage is merely an extension of the commitment that all domestic partners should have for each other and that the Church’s conception of marriage as a sacrament should no longer be enshrined in law.

The traditional concept of marriage won’t be maintained by a claim that the church’s right to free speech is under threat – though it is. It will only be maintained by preserving or by rebuilding the old consensus that, ideally at least, marriage is an exclusive union entered into for life by one man with one woman in the expectation of children.

It can’t be denied that the traditional understanding has been battered by the growing acceptance and prevalence of divorce and remarriage. The path to same sex marriage has been smoothed by the acceptance and understanding given to gay couples, often with children. The instinctive human decency that leads us to reach out to people who are trying to make the most of their circumstances however unconventional is at odds with our instinctive support for ideals of conduct that have stood since time immemorial.

It’s scarcely a decade since the Commonwealth Parliament, with bi-partisan support, amended the Marriage Act to enshrine marriage between a man and a woman. Back then, many gays still saw marriage as an oppressive institution that they wanted no part of; but how quickly things have changed.

To gays, “marriage equality” has now become a basic human right; and to others, especially young people, it’s absurd not to give people what they want when it does no harm. Then there are those of us who are more impressed by the 160 countries that haven’t embraced same sex marriage than by the 20 that have and who urge respect for the Church and caution about change.

Coming to a decision means listening to a discussion that’s allowed all who wish to have their say. No matter how respectful people strive to be, given the strength of feeling on both sides of the argument, offence is likely to be given and offence is sure to be taken. Attempting to prosecute giving offence, in those states where section 18c protections extend to religion, won’t resolve the argument but it will certainly leave one side feeling even more aggrieved.

It’s the government’s policy that same sex marriage will be decided by the people at a plebiscite after the election. The challenge for those of us against change will be to make our case even though it will often be misconstrued as an attack on everyone does not live up to the ideal. The challenge for conservatives will be to have the courage to take risks; and the judgment to avoid them in a debate where it is so easy to offend.

Let’s hope that Australians will strongly confirm what was until very recently the universal understanding of marriage. But regardless of the outcome, let’s hope that the debate is respectful, conscious of people’s long-standing attachments as much as their eagerness for change, and gives no one any reason to feel less part of a diverse-yet-cohesive Australian community.

We have Father Jordan’s example to guide us. He was always ready to speak his mind but usually managed to do so with a smile; and a disarming readiness to befriend those who didn’t agree with him.

In that spirit, let’s engage in the debate: sure that a position that’s stood the test of time has every right to be heard. The censor, after all, normally ends up damaging his own cause.