The art of writing is the art of discovering what you believe.

Before you write something down you have an impression of what you think, and impressions are forgiving. Sentences are not. Putting the thing into words forces you to choose between versions, and in choosing you find out which one you actually hold. Plenty of people discover halfway through a paragraph that they disagree with the opinion they sat down to defend.

Take something you have strong feelings about and write a page on it with no reader in mind. Do not tidy it. Read it back and mark the sentence that surprised you, because that is where your real position is.