By writing, you hold your thoughts accountable. Putting them down onto the page, or screen in my case, puts them out into the world, and putting anything out into the world means putting them up for scrutiny.

This means you have to have a strong argument, otherwise it will be ripped apart.

Sometimes I put things on the page, read them, and only then do I realize the fault in my thoughts.

Writing things, then, is one way in which you can improve your ability to form an argument, because by practicing writing, you practice the mental gymnastics ideas go through, and this further filters or strengthens your arguments before they are actually put on a page, or before they come out of your mouth.

Writing holds you accountable, but also makes your ideas more reliable.