The greatest mass murderers and pale horsemen of famine, pollution, dogmatic control of education or total elimination of it were the scientific socialists, international socialists and communists, and national socialists who attempted to totally eliminate critical thinking. And they all existed in the modern 19th, 20th and 21st Century.
Every age has had it's share of gulags and goons who attack critical thinking, it is just that in sheer numbers the plague that is perpetrated upon fellow humans has been enabled and made easier by modern inventions and technology.
These modern monsters, the ugly souls of socialism, straightjacket all critical thinking (look at the global warming kooks) often in the name of countering "religion", yet it is clear they themselves are a doctrinaire cult, yes a religion, of themself.
The extremist wing of such cults, such as in the example of the Khmer Rouge and the Pol Pot types (Saloth Sar of the "Democratic Kampuchea") in the end even outlaw doctors and scientists as "elitists" and turn the clock back to primitive agracultural slave labor society.
But the older demons are still here, the example being ISIS and such Islamic extremists. Then you see, probably without coincidence, the extremist socialist cults aligning and marching with and being friendly with and making excuses for the Islamic throwback extremists. They showed up in Ferguson.
The greatest friend of science and discovery is free market capitalism and trade. It also inspires critical thinking to drive success.
Lack of critical thinking is the state of human affairs. That is why you should not trust giving power to humans in government, especially if the government is using targets as the enemy such as religion, the Jews, whatever. Once they use targets as their vocabulary, that means they are using excuses not to look at them and what they really want to do to you.