>lostmsu - we can’t be sure. Maybe Fred looked at the fruit bowl yesterday

I mean. I mean. Did you read the last sentence? I am selling the logic that if two sane non-stupid people in good faith disagree, then it is unclear. In you example lostmsu is a fruit of your imagination. You can't be sure that fruit is sane and non-stupid. Here the argument is that we are in the ML subreddit context, and we both understand the topic at hand which raises the chances of both of us matching the criteria to near 100%.

In this context if I would start disagreeing with 1+1=2 you should at least start doubting, that e.g. I'm on to something.