6 ideas
Central planning needs agreement on one set of ends, but free people rarely hold such agreement. So power goes to whoever can build a disciplined, obedient group. That group is most easily built on the docile and the gullible, united by a shared enemy or a negative program, and it rewards leaders ready to do whatever the plan requires, without moral scruple.
Under the rule of law, the state sets formal, general rules in advance. Individuals can then predict how coercion will be used and plan their own lives around it. Planning replaces those rules with case-by-case decisions about who gets what. The state must then pick winners among particular people, and law turns into arbitrary administration.
There are no purely economic ends, because money and resources are the means to every goal a person pursues. So whoever controls the means of production decides which ends get served and which are left out. Handing economic power to the state therefore hands it power over people's values and choices.
Voters and legislators can agree that the state should plan. They cannot agree on a single detailed plan among the many competing priorities. Parliament deadlocks and looks like a mere talking shop, and the public comes to demand an expert or strong leader who will just act. Democratic planning thus creates its own pressure to delegate power beyond democratic control.
Stop sorting regimes as left versus right and ask whether the state subordinates individual ends to one collective plan. Seen this way, Nazism grew out of German socialist and nationalist planning ideas rather than as a capitalist reaction against socialism. Many of its intellectual leaders had moved from socialism to fascism without abandoning their core commitment to central direction.
Competitive markets coordinate countless dispersed decisions through prices, without any central authority needing to know everyone's circumstances. This lets society use knowledge that no single planner could gather. The state should design rules such as contract law and fraud prevention that make competition work, rather than replace competition with direction.