For most things I agree that showing is better than telling, but bias is different. If someone is in a position to judge whether my point of view is biased, then they already have a clearer idea of the truth than I do, so they don't benefit from reading my expression of that point of view. It's the people who don't already know what I have to say (or don't already know that it's false, if I am in error) who need to know how biased I am.

So I gave some information about my background, which I hope will give readers a better chance of forming an accurate idea of my state of objectivity and ignorance.