[__s]

You can get around it. A couple weeks ago I had friends over while their place had to be vacated for a few hours, they bought lunch, we played with cats

You can go after "all altruism is selfish" argument but you'll end up having to settle with "some altruism is more selfish than others"

[rhencke]

I find that experience to be persuasive, as well. It persuades me about the kindness of your friends.

[__s]

You weren't a part of this interaction. You're going with the "How can you tell if someone is vegan? ..they'll tell you" joke

[rhencke]

Do you not find yourself to be naturally persuaded by your friends through your time and experiences with them?

[__s]

Sometimes, but not always

Another situation: when I play chess online I'm interacting with people. You can argue they're persuading me about how best to play chess, but that isn't their motive nor is there a set conclusion they're trying to make me reach

You should narrow persuasion from "interaction" to a kind of conversation (such as those found in HN threads), otherwise you could start arguing all information inputs are persuasion regardless of whether the source is human