Originally Posted by: raterriegui

I was watching Christopher Schlegel's video on the position of the thumb on the left hand, and learned the fact about opposition and how it helps things flow smoothly. I myself have in the past wrapped my thumb around the neck, but brought that issue into notice when I saw his lesson. Now, I when I viewed some of his other videos, he was doing the same thing that I was! Which one is right?

They are both right. :)

The function of your fretting hand thumb is to provide pressure opposing the force of your fingers fretting notes. So, depending on which strings & frets you are currently fretting your thumb needs to move around in order to maintain that opposing pressure. I call it an axis of power. It essentially means to move your thumb around to best oppose your fretting fingers for maximum efficiency.

So, the default, or starting position, for beginners is firmly on the backof the neck. That's to teach beginners not to palm the neck & to learn to position their thumb for leverage & opposing force.

From there you can move it around as necessary depending on which notes you are playing. Make sense?

I explain in depth here.

https://www.guitartricks.com/lesson.php?input=12188&s_id=605

Hope that helps!