The issue isn't even how rational people are. Even if our lack of rationality was no problem, it would still be impossible to get someone to reveal their true preferences without a system where they have to sacrifice value to obtain something. This idea that calculation is the problem with the economy is strange to me, as if there's some algorithm we know to maximize good, that just needs some inputs that people will provide by survey or something, and the only issue is that we can't scale up our computers enough to run the algorithm. What is this algorithm? The truth is that preferences are only revealed when individuals are forced to make difficult and uncomfortable decisions about what's important to them. People simply don't prioritize their needs until they have to. And the nature of humanity is that we are also prone to lying if overstating our preferences has a selfish benefit. Unless socialists seriously consider this, any algorithm is likely garbage-in, garbage-out.