“One problem (of many) with Soviet-style command economies is that they can only work if people know what they want and need, and can define and express their wants adequately. But this is impossible, because not only do people not know what they want, they don’t even know why they like the things they buy. The only way you can discover what people really want (their ‘revealed preferences’, in economic parlance) is through seeing what they actually pay for under a variety of different conditions, in a variety of contexts. This requires trial and error – which requires competitive markets and marketing.”