The philosopher Nicolas de Condorcet believed in progress. Looking around him in late 18th-century France, he saw improvement everywhere, a trend he thought certain to continue as learning became more widely diffused. The growth of scientific knowledge, he was sure, would inevitably benefit public morality, while social evils would disappear as the ignorance that caused them melted away.

But for knowledge to be diffused, the men of the Enlightenment felt, control over it would first have to be wrested from the clerics who ran the schools and universities. It would also have to be rendered more open and less dependent on authority or divine “revelation”. The pursuit of truth required competition between rival ideas and theories, a condition requiring an at least provisional tolerance of opposing views.

For more than a century after the Reformation, books and pamphlets carried fierce polemics between Catholic and Protestant controversialists and between rival Protestant sects. We do not know how many people’s minds were changed by this flood of words but it certainly helped provide a good living for thousands of printers, publishers and booksellers.

The idea that tolerance might be a good thing in itself began to make its way in the late 17th and 18th centuries, partially as a reaction against Louis XIV's vicious persecution of French Protestants. But the persecuted could become persecutors too: the philosopher Pierre Bayle, who had fled from France to Rotterdam, was increasingly distressed by the cruelties that ensued when sectarianism was backed by the force of law as orthodox Protestantism – whichever brand happened to be orthodox in a particular place at a particular time – combated "heresy". Increasingly, he came to believe that no one should be prosecuted for their beliefs – and certainly not any Protestant.

Agree to disagree
As the 18th century progressed, ideas of civility and politeness increasingly began to make their way and were applied to the style in which arguments should be conducted and ideas discussed. People should be able to disagree, it was now thought, without feeling the need to cut off one another's heads. The new optimistic tone is reflected in the name given to the "virtual space" in which those interested in thought exchanged ideas internationally – the Republic of Letters.

Over the next 150 years democracy, reform and intellectual freedom advanced steadily. In the middle of the 20th century they were seriously challenged by totalitarianism but since 1989 free speech, freedom of association and, of course, freedom to “do business” have again emerged as the cherished centrepieces of our civilisational model: we can, on the whole, say what we want, write what we want and worship where, or indeed what, we want.

This is all for the best of course, but could it be that freedom of speech has turned out to be a somewhat negative virtue, that we are more blessed in the simple fact that people are not being jailed for what they write than we are in the benefit, intellectual or spiritual, we derive from what they actually do write?

About 15 years ago, a phenomenon that has since been dubbed cyber-utopianism saw an enormous investment of faith in what was believed to be the politically transformative potential of the internet, a new world without borders or restrictions and with a huge capacity to promote democracy and freedom and unite people of all races and nations irrespective of the wishes of governments.

This optimism has since dissipated somewhat and more recently we seem to be more concerned to protect ourselves from the intrusions on our privacy of huge – and hugely profitable – tech companies and state security apparatuses.

Short attention span
Meanwhile, analysts like Nicholas Carr (author of The Shallows) believe our increasing use of the internet has shortened our attention spans, diverted us from more worthwhile forms of leisure and social interaction, and rendered us resistant to any form of thinking that requires persistence and concentration.

It is true of course that, through forums or the comment facilities of online publications, the internet can facilitate the exchange of views. But can these views often be called ideas? In the old vaudeville theatres the term “the peanut gallery” was applied to those in the cheap seats who derived as much enjoyment from showering the stage with nuts as from the artistes’ efforts to entertain them. And now, in what has become known as the bottom half of the internet, much heat, much bitterness and little light is generated by the detritus flicked – as frequently at each other as at the “artiste” – by contributors whose seats are not cheap but free.

Condorcet’s hope that knowledge would of itself produce virtue and happiness was a naive one. Equally it seems that the idea of democratic emancipation and renewal through the internet is destined to join the end of history, the leisure society, the paperless office and the Arab Spring in the long list of great futures that didn’t happen.

In 1856, Henry David Thoreau wondered about the advent of the electric telegraph, whose object seemed to be "to talk fast and not to talk sensibly".

Sensible talk may be too much to expect, but could we ask the punters to be careful with the peanuts?

Breda O'Brien is on holiday