"Think for yourselves and let others enjoy the privilege to do so too," he said in just one of many of his ideas that seem relevant to us today.

"It is dangerous to be right in matters where established men are wrong," is another that could have been penned for exactly this moment in our history.

It was a search for the origin of the misattributed quote, "I disapprove of what you say, but I will defend to the death your right to say it" that led me to dabble among his many delightful aphorisms.

That exact phrase apparently belongs to the English writer Evelyn Beatrice Hall, who wrote it as a summary of Voltaire's thinking rather than as a direct quote.

But no matter. The phrase came to mind as I followed the national conversation driven by Cape Town artist Brett Murray's now notorious painting of Jacob Zuma as Vladimir Lenin with his fly open.

It seems a poor piece of satire to me - something one might expect to find in the annual exhibition of the matric art class at a progressive school. It has none of the bite of Zapiro's Lady Justice cartoon and hardly seems to deserve space on the gallery wall. But here's the rub.

Once the curators of the exhibition and Murray himself had decided to hang it, anyone committed to the values of our free society was obliged to defend to the death their right to do so.

A similar imperative shaped my own response to the furore when the Minister of Agriculture, Forestry and Fisheries, Tina Joemat-Pettersson, refused to address the Cape Town Press Club while the DA spokesman on her portfolio, Pieter van Dalen, was present.

As an active member of that club some years back, I suggested it should change its name to the Cape Town Luncheon Club because its events attracted few reporters, it did little to defend their professional interests and it accepted substantial sponsorship of food and drink from corporate entities about which reporters often write.

(I had seen several slightly bewildered guests taken aback at the patently non-press audience of the city's press club and their often loaded questions, which bore none of the neutrality that journalists would have sought to maintain.)

But once Joemat-Pettersson had put her demand, the club was wrong to allow Van Dalen to leave.

The organisers should have shown the minister the door and given the floor to Van Dalen.

Though that ministerial tantrum was about being afraid of informed awkward questions, censorship is as much about preventing someone from hearing as it is about preventing someone from speaking.

Then there was the display of petulance outside the Johannesburg offices of Cosatu, where unionists afraid to hear an alternative viewpoint came out onto the streets to, as they put it, "defend" their castle.

The federation leadership argued there was no point in hearing the DA out because the minds of the workers were made up and would not be changed.

If that were true, of course, there could have been no harm at all in allowing the opposition to march to their front door and present their argument.

It could only be because Cosatu feared that something the DA said might strike a chord with the unemployed and cause them to defect to a group they judged to be more protective of their interests.

In the same way, a Christian who blocks his ears to the atheist argument is a poor defender of his faith.

Viewed in isolation, these incidents might seem to be trivial, but they represent a much more dangerous trend.

The democratic system we chose in 1994 presumes that power will change hands from time to time. That is one of the reasons why democracy works.

Peter Mokaba told me many years ago that the ANC would never be voted out of power and that if the electoral verdict went against it, that would have been because the people had been duped.

In that case, he said, the ANC would be within its rights to ignore the poll result.

Since then, the ANC has proved its commitment to democracy by accepting electoral defeat in several municipalities and one province.

The ANC did flirt briefly with the idea of taking over the DA-ruled Cape Town municipality under the constitutional provision for a province to take over a misruled council. But reason prevailed.

So far, there is no reason to believe the Mokaba approach is dominant. But the tyrannical rule of the ousted ANCYL leader Julius Malema showed it is there.

Remember he threatened that any ANC leader who opposed his nationalisation drive would have a short political career?

Where data and analysis are freely available, it is unlikely that real wisdom will lie close to the poles of competing social ideologies.

There will always be some who are silly enough to believe in silver bullets, but there is wisdom in crowds where they are given the freedom and space to weigh all the evidence and make up their own minds.

If South Africans are allowed to listen to all the ideas about how to create jobs and these ideas are not tied to political loyalties that insist "my party, right or wrong", we will choose enough of the viable plans to get going and will have the freedom to dump or adapt those that don't work.

But if we dare not listen to the other side, if the dignity of our leaders is so fragile that it can be dented by a painting and if we cannot tolerate the notion that our view may not dominate forever, ours is a poor democracy and probably not destined to last very long.

• Brendan Boyle is editor of the Daily Dispatch