Yours & Theirs
Everyone involved with your viva will have opinions.
There’s a lot of truth and certainty by the time you have finished your thesis but you could have plenty of unanswered questions too. Plenty of space for doubt. Plenty of space for wondering. Plenty of space for believing but not knowing for sure.
You will have opinions about some things. Your examiners will too. It’s possible that your opinions will collide or oppose. That’s not as big a problem as you might believe.
Whether you have to defend your view or unpick your examiner’s, start with why. If you need to convince with your opinion ask yourself why you think it is true to motivate your response. If you aren’t sure of your examiner’s point then ask yourself why or ask them why.
Once you know why someone holds their opinion you can understand more. You can figure out what you actually agree with and what you don’t. You can see the root of the problem or understand how to find common ground.
When defending or exploring opinions, start with why.
(this works very well outside of vivas too!)