In Britain, so it is said (I have my doubts whether things really were less partisan), we had a period of "Butskellism" - a term coined to cover the political consensus of the 1950s. Butler was the Tory Chancellor of the Exchequer (1951-55), who succeeded Gaitskell (who went on to lead the Labour Party).
In the US, there was once a time when Members of Congress worked across the party divide.
But today extreme language is used - and bipartisanship is a long forgotten tradition. What's gone wrong?
Well - as I wrote in my first sentence, there may be a bit of 'rose-tinted glasses' at work here. Elections and policy battles have always been hard fought. Many of this generation's predecessors could be extremely acid tongued [Winston Churchill for example].
But partisanship certainly has increased. I thoroughly recommend Sean M Theriault's "Party Polarization in Congress" and Mann & Ornstein's "It's Even Worse Than It Looks" for descriptions and explanations.
(These link to the 'Kindle' versions - but you can also get them as paperbacks or Hardbacks).
Can I suggest my own thesis - and please come back to me with your comments via firstname.lastname@example.org - and that is that in the US, UK and France one of the key (but not the only) factor is the resurgence of what can be described as 'Extreme Conservatism'. This isn't the 'One Nation' Conservatism associated with Harold Macmillan and the Tories who supported the post World War Two consensus - who saw a positive role for the State and didn't seek to aggressively redistribute wealth from the many to the few. It isn't the conservatism associated with the Republican Party under Martin, Halleck, Ford, Rhodes, Michel and President Eisenhower.
This is a conservatism that is fundamentally in favour of a minimal state - still around to fight external and internal enemies - but not providing for the needs of citizens. (Private companies can do that - with their own profit as the primary motivation); a State which doesn't 'interfere' by regulation - except as a temporary response to yet another scandal (be it in banking; in food manufacturer; or after a 'disaster').These extreme-Conservatives treat their political opponents as 'illegitimate' (see the false claims about Obama; the language being used by UMP politicians in the debate in France over 'mariage pour tous' [See Le Monde 31 March 'L'electorat de droite se radicalise' p1, 2-3, 16 - "a rhetoric of de-legitimation of the President Francois Hollande")] - and will refuse to work with their elected opponents [see the activities of many Republicans in Congress].
"Conservatism" is a phrase which suggests the good old ways of the past; 'traditional' even reactionary - but this extreme-Conservatism is radical - it seeks to tear down not uphold.
But it isn't new!
Richard Hofstadter described previous versions in the aftermath of Joe McCarthy and as Goldwater led the Republicans to defeat at the 1964 Presidential Election. His book (The Paranoid Style in American Politics) is a classic - and I've been re-reading it whilst away in Southampton; Sheffield and Suffolk. In its final version it may be 48 years old - but it describes what we would so easily recognise today.