Necessary Minimum of Agreement

From George Orwell's Homage to Catalonia:

Between the Communists and those who stand or claim to stand to the Left of them there is a real difference. The Communists hold that Fascism can be beaten by alliance with sections of the capitalist class (the Popular Front); their opponents hold that this manoeuvre simply gives Fascism new breeding-grounds. The question has got to be settled; to make the wrong decision may be to land ourselves in for centuries of semi-slavery. But so long as no argument is produced except a scream of 'Trotsky-Fascist!' the discussion cannot even begin. It would be impossible for me, for instance, to debate the rights and wrongs of the Barcelona fighting with a Communist Party member, because no Communist--that is to say, no 'good' Communist--could admit that I have given a truthful account of the facts. If he followed his party 'line' dutifully he would have to declare that I am lying or, at best, that I am hopelessly misled and that anyone who glanced at the Daily Worker headlines a thousand miles from the scene of events knows more of what was happening in Barcelona than I do. In such circumstances there can be no argument; the necessary minimum of agreement cannot be reached. What purpose is served by saying that men like Maxton are in Fascist pay? Only the purpose of making serious discussion impossible. (p. 178-9)