Do higher rates of imprisonment reduce crime? Is crime a result of poverty, unemployment, and the like? Are alternatives to incarceration more effective in preventing criminals from repeating their crimes?
Some people would hesitate to try to answer any of these questions before going through a lot of hard evidence and thinking it over very carefully.
But many on the left can answer immediately because they know what answers are already in vogue on the left and that the only reason others don't accept those answers is because they are behind the times or just hard-hearted people who want to punish.
It is one thing to believe that policy A is better than policy B. It is something very different to believe that those who believe in policy A are wiser, more compassionate, and generally more worthy human beings than those who believe in policy B.
Turning the empirical question of the results of policy A versus the results of policy B into the more personal question of a wonderful Us versus a terrible Them makes it harder to retreat if the facts do not bear out the belief.
If the choice between policy A and policy B is regarded as a badge of personal merit, either morally or intellectually, then it is a devastating risk to one's sense of self to make empirical evidence the ultimate test.
Not only in the United States, but in other countries as well, the political left has held steadfastly to its assumptions and beliefs about crime for at least two centuries, not only in the absence of hard evidence but in defiance of two centuries' accumulation of evidence to the contrary, from countries around the world.
Where the dominance of the left is greatest in the media and in academia, for example facts to the contrary are seldom heard.
The futility of imprisonment, for example, is a dogma on the left. It does no good to point out that crime rates in both Britain and the United States soared during the decade of the 1960s when poverty rates were going down and imprisonment rates were also going down.
It does no good to point out that soaring crime rates in the United States began to turn down only after the declining rate of imprisonment was halted and reversed, leading to a rising prison population much deplored by liberals.
It does no good to point out that Singapore's imprisonment rate is more than double that of Canada and its crime rate less than one-tenth the Canadian crime rate. Many in the west were appalled to discover some years ago, that an American first offender in Singapore was sentenced to corporal punishment.
Few of the indignant critics bothered to consider the possibility that this might be a way to prevent the young man from becoming a second offender and perhaps saving him from a worse fate later on if he continued to disregard laws.
Self-defense against criminals is anathema to the left in both Britain and the United States but in Britain the left has greater predominance. Britons who have caught burglars in their homes and held them at gunpoint until the police arrived have found themselves charged with a crime even when it was only a toy gun.
Given the prevailing view in the British criminal justice system that burglary is a "minor" offense and the fierce hostility to guns, even toy guns, the homeowner is far more likely to end up behind bars than the burglar is.
The left's jihad against gun ownership by law-abiding citizens has produced a flood of distorted information. International comparisons almost invariably compare the United States with some country with stronger gun control laws and lower murder rates.
But, if facts really mattered, you could just as easily compare the United States to countries with stronger gun control laws and higher murder rates Brazil and Russia, for example.
You could compare the United States with countries with more widespread gun ownership Switzerland and Israel, for example and lower murder rates. But that's only if facts are regarded as more important than the dogmas of the left.
Millions of crime victims pay the price of the left's illusions about crime and about themselves.