Did the descent of our common discourse to the current level of incivility begin with Twitter, with the internet, with cable television? Or were the dynamics already present 50 years ago, as demonstrated by two of the most erudite figures in American letters?

In the summer of 1968, ABC News, trailing the other networks in ratings and consequently cash on hand, decided to depart from gavel-to-gavel coverage of the Republican and Democratic national conventions. ABC engaged William F. Buckley, a conservative, and Gore Vidal, a liberal, to debate nightly during the convention coverage, first in Miami for the Republicans, and three weeks later in Chicago for the Democrats.

The two went at each other for 10 nights, as much pugilists as belletrists. Their exchanges were substantive and intelligent, but also descended to personal attacks. After the debates, both Buckley and Vidal continued the vituperative exchanges in long essays for Esquire, which in turn gave rise to even longer litigation in the courts. There was no amicable reconciliation. Buckley died in 2008, two years before Vidal; the latter penned an obituary expressing his view that the former was (deservedly, he thought) in hell.

The low point of their television debates was an exchange in which Buckley exploded after Vidal called him a “crypto-Nazi.”

“Now listen, you queer,” Buckley replied. “Stop calling me a crypto-Nazi or I’ll sock you in the goddamn face and you’ll stay plastered.”

Both the gay slur and the threat of violence were a departure from the otherwise genteel disposition Buckley usually displayed, and it remained permanently a prominent part of his long career. Vidal thought that the exchange proved that he bested Buckley. On his part, Buckley came to regret his words and in later years generally refused to speak about the 1968 debates.

ABC was delighted. The cost of engaging two of America’s leading intellects for two weeks was pennies on the dollar compared to the cost of broadcasting live convention coverage. Ratings were excellent. The lesson has been learned over and over again in the half-century since; there is no cheaper television to produce than talking heads, and ratings are driven by those talking heads going low rather than high.

Was Buckley-Vidal the father of CNN’s Crossfire in the 1990s and today’s shouting matches on cable news? That was the premise of an excellent 2015 documentary on Buckley-Vidal, Best of Enemies, which argued ABC’s straitened circumstances in 1968 gave rise to economics that have fuelled combative cable television, partisan talk radio and rhetorical bloodsport on social media. Talk is cheap to produce, but can be lucrative when sold.

But what kind of talk?

Buckley-Vidal was memorable not because two men of superior intellect debated the salient issues of the day, but because of how they debated, putting personal attacks into their punditry. In the generations that followed, legions of commentators who lacked both the intelligence and rhetorical mastery of Buckley and Vidal made the personal attack the first resort, and sometimes the only resort. Hence the mindlessness of much commentary today.

It would be wrong to attribute the genesis of uncivil commentary to Buckley-Vidal. American newspapers in the late 19th century and Fleet Street in the 20th routinely ran headlines and stories that would be shocking today. Scurrilous journalism did not begin in 1968.

Yet there was something new. The pundit as a star attraction in his own right, not ancillary to the action but at the centre of it — that was a new thing which Buckley-Vidal made prominent and economically attractive. Labour-intensive and costly news reporting has shrunk in recent years in favour of relatively inexpensive commentary, to the extent that commentators are the star attractions at many news agencies.

Combative commentary is not going away. Is it too much to hope for combative exchanges of a qualitatively higher sort, as Buckley and Vidal provided in 1968? Most likely. As in economics, bad money drives out good. There is little room for erudite name-calling when vulgar name-calling is plentiful.

Fifty years on from Chicago 1968, the violence in the streets remains indelibly marked in the history of American politics. But the rhetorical violence in the TV studio has lived longer in American — and global — political culture.