> Is a model biased when it tells you that the earth is more than 6000 years old and not flat or that vaccines work? Not everything needs a "neutral" answer.

That's the motte and bailey.

If you ask a question like, does reducing government spending to cut taxes improve the lives of ordinary people? That isn't a science question about CO2 levels or established biology. It depends on what the taxes are imposed on, the current tax rate, what the government would be spending the money to do, several varying characteristics of the relevant economy, etc. It doesn't have the same answer in all circumstances.

But in politics it does, which is that the right says yes and the left says no. Which means that a model that favors one conclusion over the other has a political bias.