By traditional standards, the first televised US presidential debate on Monday night produced a clear result. Hillary Clinton’s experience, grasp and temperament proved superior qualities to Donald Trump’s forcefulness, rambling and egotism. Fears that Mrs Clinton’s recent bout of pneumonia would cause her to stumble proved unfounded. Instead, Mr Trump’s sniffing caused more comment on the night. But the question, in this most unpredictable of elections and in a new media world, is how far traditional standards matter any more.

Mrs Clinton repeatedly put Mr Trump under pressure on his finances, his taxes, his climate change denial, Iraq, Russia, Barack Obama’s birth, and race. Mr Trump countered with powerful lines about unfair trade deals and immigration and was both personal and boastful. Mrs Clinton stayed careful but grew more relaxed as the 90 minutes evolved. Mr Trump got angry and repeatedly rose to the bait. To adopt the dismal boxing terminology that tends to be wheeled out on such occasions, neither candidate landed the fabled knockout blow. There were plenty of low punches. But Mrs Clinton obviously won on points.

Yet traditional responses to the debate may not suffice. Politics is in flux in many democracies, America included. And both these candidates are already very well known. Neither has to introduce themselves to the voters. Most people have an opinion about both of them. Each is also already a very divisive figure, both to the other side and, to an unusual extent in this race, on their own side too.

The very fact of seeing two such dissimilar figures together in the presidential debate studio was a reminder of how 2016 is different. On the one hand, Mr Trump, a candidate whose self-confidence has swept him to the Republican nomination on a wave of predominantly white anger without any experience of government whatever. On the other Mrs Clinton, whose conventional qualifications for the top job are beyond question, but whose political instincts seem to date from a different era. The fact that here was the first woman to be taking part in a presidential debate almost passed without notice – though Mr Trump could not resist some nasty innuendos.

The televised debates are always built up as great moments of national attention and decision. Sometimes they are. The reality is that while debates may inform opinion, there’s a question as to whether they shift it dramatically. As the Guardian’s Alastair Cooke wrote of the first Nixon-Kennedy debate in 1960, the Republicans to whom he spoke afterwards thought Nixon had won, while the Democrats believed Kennedy was the victor.

There is still a lot of sense in that more circumspect approach today. Most voters already have a preference going into the debate. They look to the exchanges to confirm them in their judgment. Relatively few voters actually tune in with an innocent mind. Last night was no exception to that. Those who are appalled by Mr Trump will have seen and heard a Clinton victory. Those who cannot abide Mrs Clinton will have seen and heard Mr Trump tell truth to power.

The 2016 race may be an exception in other ways. The polls have narrowed in September, both nationally and in the battleground states that will determine the result in November. The debates may therefore make a difference this time. That was a subtext in Monday’s exchanges. Mr Trump name-checked Michigan and Ohio, states he must win, twice in the first 30 minutes. Mrs Clinton aimed a lot of her remarks on criminal justice and police at black and Latino voters, and had sections on the banks and social justice that reached out to wavering supporters of Bernie Sanders.

Both candidates made sure to showcase their well-tested strong messages: Mr Trump to make America great again, Mrs Clinton to question her opponent’s fitness to have his finger on the nuclear trigger. Mrs Clinton certainly missed a lot of opportunities to hit back instantly at Mr Trump’s untruths that a better debater would have seized on. Yet Mr Trump said many things that may come back to haunt him on social media and in campaign ads in the days to come. Mrs Clinton, by contrast, made few gaffes.

Some will say neither candidate is worthy. In the end, though, one of them will be president of the United States in January. Mr Trump came into this week’s debate with an opportunity to show that there is more to his candidacy than the recklessness, rudeness, falsehood and appeal to racism that has marked it over the last months. On Monday he blew his opportunity. On the biggest stage of his career he showed he is unfit to rule, that he is a danger to America and to the rest of the world. But will enough voters care? If one thing came clear and undeflected out of Monday’s debate it is that Americans cannot afford not to.