Radically different conclusions about a whole range of issues have been common for centuries. Many have tried to explain these differences by differences in conflicting economic interests. Others, like John Maynard Keynes, have argued that ideas -- even intellectually discredited ideas that political leaders still believe in -- trump economic interests.
My own view is that differences in bedrock assumptions underlying ideas play a major role in determining how people differ in what policies, principles or ideologies they favor.
If you start from a belief that the most knowledgeable person on earth does not have even one percent of the total knowledge on earth, that shoots down social engineering, economic central planning, judicial activism and innumerable other ambitious notions favored by the political left.
If no one has even one percent of the knowledge currently available, not counting the vast amounts of knowledge yet to be discovered, the imposition from the top of the notions favored by elites convinced of their own superior knowledge and virtue is a formula for disaster.
Sometimes it is economic disaster, which central planning turned out to be in so many countries around the world that even most governments run by socialists and communists began freeing up their markets by the end of the 20th century.
That is when the economies of China and India, for example, began having rapidly increasing growth rates.
But economic disasters, important as they are, have not been the worst consequences of people with less than one percent of the world's knowledge superimposing the ideas prevailing in elite circles on those subject to their power -- that is, on the people who together have the other 99 percent of knowledge.
Millions of human beings died of starvation, and of diseases related to severe malnutrition, when the economic ideas of Stalin in the Soviet Union and Mao in China were inflicted on the population living -- and dying -- under their iron rule.
In both cases, the deaths exceeded the deaths caused by Hitler's genocide, which was also a consequence of ignorant presumptions by those with totalitarian power.
Many on the left may protest that they do not believe in the ideas or the political systems that prevailed under Hitler, Stalin or Mao. No doubt that is true.
Yet what the political left, even in democratic countries, share is the notion that knowledgeable and virtuous people like themselves have both a right and a duty to use the power of government to impose their superior knowledge and virtue on others.