You may think that you know the thoughts you're thinking. Yeah, me too. It turns out it's not that simple. Your thoughts are just shadows of thoughts. They're incomplete, they're fuzzy, they lack boundaries, they lack rigour.
Thoughts are transient as well. Did it ever happen to you that you had a brilliant thought you were sure you'll remember? Then you couldn't remember it an hour later? Yup, that was a temporary collision of electrons in your brain.
The best way to realise that our thoughts are incomplete is to try to explain them to someone or to write them down. It turns out that only when you actually try to do that the thoughts become real things. They take shape. It forces you to find illogical steps, gaps and undefined areas of your thinking. That's when you become aware of just how undefined your thought was. You're forcing your brain to give the ideas shape and clarity. Psychologists have a word for bringing thoughts to the real world: externalization.
So the next time you're pondering something that slips out of your conscious grasp try to write your thinking down. It will enforce your views. It's also easier to use writing because unlike speaking it doesn't involve other people. There's no one to object you, there's no one influencing your thought process. Just you and the text. Write it down, leave it for a few hours and then read. You'll be surprised :)