From my response to Mike Huemer’s target essay on this month’s Cato Unbound:

As a free bonus, Huemer dulls the urge consequentialist libertarians
often feel to stretch the truth, to make stronger claims about the
benefits of libertarian policies than the evidence warrants. Thus,
libertarians who oppose a war with Iran don’t need to confidently
assert, “This war will clearly make matters even worse.” We should just
stick with what we really know: “We shouldn’t murder thousands of
innocent people unless we have strong reason to believe doing so will
make matters vastly better. And we don’t have a strong reason to
believe this.”

Needless to say, the consequentialist urge to stretch the truth is not limited to libertarians.  In fact, Robin Hanson may be the only consequentialist I’ve ever met who seems to lack the urge to stretch the truth. 

On what grounds, you may ask, do I make this accusation?

First, consider the policy views consequentialists held before they studied philosophy and social science.  Then look at the views they hold after studying these subjects.  Notice the suspiciously high correlation?  <sarcasm>It’s almost as if people grandfather in their pre-existing policy preferences rather than meticulously judging them case by case against the facts.</sarcasm>

Second, consider the very high stability of the policy views of the typical mature consequentialist.  A real consequentialist should be constantly fine-tuning his policy views as new evidence arrives.  After all, as soon as the net expected benefits of your current favorite policy fall $.01 below the net expected benefits of any alternative policy, consequentialism requires you to purge your old favorite policy and adopt a new one.

Finally, consider the very high certainty of the typical mature consequentialist.  No human being has the time to consider more than a small fraction of policy-relevant evidence.  And even if you did have the time to review all existing evidence, you’d still be very far from fully understanding what’s going on.  Call it a cliche, but the real world really is extremely complex.

Are people with more nuanced moral theories really better social scientists?  That’s complex, too.  Consequentialists do spend more time studying social science than non-consequentialists.  But non-consequentialists profit more from a given study time, because they don’t need empirical closure to look themselves in the mirror.