[paulojreis]

There's nothing in your statement "it is against human nature" that would imply that it was just an expression of your opinion. You stated it as clearly as possible, yet you have no basis for this. It's very sad to see the standards drop so low when the discussion regards human behaviour; it borders on religious faith. People believe X regarding human behaviour in the same way other people believe in baby jesus.

> the challenge to find a counter-example to my argument is called proof by contradiction.

I don't think "proof by contradiction" means what you are "expecting", really. Look it up. You'll see why and how fallible it would be as a method for human and social sciences.

[mvitorino]

How about the start of my sentence: "Absolutely agree". Would that imply it is an expression of my opinion, in your view?

Standards? I think you are being a bit too hard on yourself and us. These are just comments on a web forum.