I see the following sentences.
1 Was it right for the Americans to drop nuclear bombs on Hiroshima and Nagasaki? Conventional wisdom has it that the decision saved many lives in the long run, but this view has been frequently challenged.
2. Conventional wisdom has it that all kids want to be footballers when they grow up. Unfortunately, it doesn't quite give the full picture.
3. Conventional wisdom has it that they have to keep trying because the consequences of the euro's collapsing are too awful to contemplate. But is that really true?
I don't know the construction "Conventional wisdom has it that + clause" . What does IT replace, please?
It means that most people believe something or an idea is commonly accepted, often when a contrary opinion is about to be given. The idea that the nuclear bombs brought the war quickly to an end is a common one, but a minority question this and argue that this is incorrect.