This is the million dollar question. My answer is that no one is in every regard 100%. We are all shaped by what we take in and surround ourself with. The “think for yourself” starter base pack is turn off the “news” though. That will move you towards 100%.

Here's my very jestful response - you never are. You speak in wordd created by other people, all who have their own agenda. You act in frameworks that are derivative of your predicessors. Even the most righteous individuals are still humans with their own intentions, no matter the narrative they are putting forth. If there is an ultimate truth, I'm doubtful it can be articulated. So the maximum that follows - be self critical, be critical of others. Think with ideas rather than about them - where does this thinking lead beyond what is immediately stated? Continually reorient and then resolidify yourself against that truth, even if local truths can lead you astray. A sort of frantic ideological oscillation that changes bias over multiple time scales.

All my thoughts are very stupid. That’s usually a pretty good indicator.