Question

Hello Rabbi,
Yesterday I spoke with a friend who asked/argued the usual questions, and I felt how all the most basic principles in your teaching had slipped my mind.
His wording was something like this: no matter what position I arrived at, and whether I arrived at it in accordance with the society I grew up in or in opposition to it (or in any other relation to it) — it will always be the result of the totality of my characteristics plus the totality of the events I went through in life. And that is true of every person. A kind of conscious determinism.
So why is it justified to feel that my position is more correct than someone else’s position? 
The way I phrased it here sounds a bit weak, but I hope that from your experience you’re already familiar with similar formulations and can get to the root of the matter (= my friend’s view).
 
Thank you very much!