@hunkyscotsman On Marx vs Keynes, UBI would be irrelevant in a communist system, since everyone would already (in theory, if not in reality) have everything they need.

But by the 1930s, it was clear that both pure communism and pure free-market capitalism were untenable (except as political slogans), which is why rich counties today use blended systems, about 50:50 public:private economic activity, ±10% either way. UBI is a way to make the public part more equitable and efficient.