I've noticed this on HN for genetics- and especially evolution-related topics. Many commenters here confidently state as fact things which turn out to be dead wrong. If your knowledge of evolution is limited to having read 'The Selfish Gene', you should be aware that you likely carry several misconceptions and also have many large gaps in your knowledge.

It turns out that, although possibly a virtue when programming, hubris can easily lead you astray if you're outside your field of expertise. Humility is more useful in these situations.

I am sure that this holds true for many other topics; it should give us all pause before we accept statements as true just because they sound agreeable to us, or before we regurgitate opinions whose veracity we're not in a position to verify.

Incidentally, I've also spotted this on the TV show QI, many of whose clever 'facts' are misleading at best or just plain incorrect.