Post-Truthism is nothing new. Following the Truth Reform Act of 1976, it became every citizen's civic duty to attend de-education classes. The state instinctively felt that knowledge and the educated people who wield it destablize governmental plans, especially those that routinely and deliberately disregard verifiable facts.
According to one de-education textbook: "A good or 'Schrödinger' fact is simultaneously true and untrue until such a time that someone in authority tells you which, though they may change their mind or substitute the fact entirely for another piece of information, fabricated or otherwise, that suits their personal or political needs."
It could take many years for a citizen to unlearn everything, particularly because they first had to learn the complex method of how to unlearn. (Also see the How to Burn Books book).
Additionally, because de-education classes were compulsory (and expensive), some people opted instead for lobotomies by backstreet barber-surgeons, who, it was later revealed, received government funding. These unregistered practitioners would lay their patients' heads on the bottom step of a staircase, then release a Slinky attached to a sledgehammer from the top step. If this procedure was unsuccessful, they would force the patients to binge-watch ITV talent shows such as Opportunity Knocks or the BBC's Come Dancing programme.