"Confirmation Bias" is now the term of choice amongst the ignorant.
Basically, Confirmation Bias is the ability of people committed to an ideology to confirm their beliefs by looking at research that confirms their opinion.
An example of this would be global warning. Those who are convinced about global warming being the result of human activity would look at studies and see those studies confirming their beliefs. Those who are not convinced look at other studies that seem to confirm their own beliefs. Thus both sides are guilty of confirmation bias.
The problem with this is that it essentially allows ignorant people to get away with believing any old rubbish. Logically, if two people believe in totally contradictory beliefs and there is only a chance that one of these beliefs is true, then both parties cannot be guilty of confirmation bias. Indeed, one party is right and has the facts to prove it, while the other party is wrong and it looking at the wrong facts (or even outright falsehoods).
So, in regards to global warming and whether it is a man made condition or not - the reason why I have come down on one side of the equation is because a) I have thought about it for many years and explored many different avenues that affect global warming, and b) I respect mainstream scientific opinion on the issue.
Those who haven't looked through all the facts carefully and who don't think that mainstream scientific opinion on a scientific subject is believeable will come up with the alternative theory.