Published in Unpopular Essays, 1950, Russell sets up the following trichotomy as a forecast to be realised before the end of the 20th century.
a) The end of human, and possibly all other, life
b) A collapse in human numbers and a return to barbarism
c) A unification of the world under a single government.
He prefaced these options by suggesting that something unforeseeable might also happen. And he rounded them off by suggesting that what he could say without hesitation was that humanity could not possibly continue as it was.
Ignoring the implicit option d) of something completely unforeseeable then, (which makes this not a trichotomy but whatever a 4 option-scenario is called), Russell has surely created a fallacious (and lesser spotted) false trichotomy. For certainly none of his options came to pass by the year 2000, and arguably humanity had largely carried on as it was.
Russell has clearly buried an IED in his front lawn with this argument, to be trodden on at a later date. But forecasting is a perilous business and superior intellect is no guarantee of accuracy. He was not the first, nor will be the last, to blunder in this regard.
More surprising perhaps is the curious argument a few pages on. Here Russell argues that either Soviet communism or American capitalism will come to dominate the world. He expresses a preference for the latter, but backs his commitment with a very curious notion. He does not prefer Americanism because capitalism is inherently better than communism. Rather he prefers it because of the respect it (Americanism) affords ‘freedom of thought, freedom of inquiry, freedom of discussion, and humane feeling’. Whereas the Soviet outlook values none of these things.
But surely here is a more serious informal fallacy at work? For Russell is ignoring the rather obvious point that he is presuming these freedoms have nothing whatsoever to do with capitalism, nor their absence anything to do with communism. He tacitly suggests that were America to adopt communism, these freedoms would continue to exist. A curious political philosophy this that surely only a theoretical Marxist could reasonably argue. The evidence for liberalist communist states is thin on the ground. For illiberal capitalist states we have the recent example of China. But on the whole, presuming the complete separability of capitalism and freedom of thought/inquiry/speech whilst also asserting the compatibility of these latter with Soviet-style communism, seems more than just contrarian; it is surely to be wilfully oblivious to a mountain of evidence.
Unpopular Essays is an excellent collection, but this particular essay is a bit of a turkey and easily the most dated of the anthology.