@lukestoke: Thanks for your comment.
I think the concept of loss aversion explains our initial stance of "no" over yes
I won't agree with this. Even when they have nothing to loose (or win), people tend to say no or think no at first.
Listen around you ... so many people start their sentence or comment with "no, ... " even if the whole sentence after doesn't contains any negation, even sometimes when it is to approve what has been said previously. The funniest IMO is "no, it's ok".
The concept of straw-man fallacy (you misrepresented someone's argument to make it easier to attack) is also interesting but more focused on the content of the arguments and the opposition between both parts.
I linked to wikipedia to hopefully better explain what I mean by loss aversion. To me, it's the psychological underpinning for why people start with no and think no at first.
Basically, we want to maintain the status quo which involves saying "no" to just about every possible thing because most things represent a change in the current state of nature, even if it's just a new piece of information.
Anyway, that's my view on it. Thanks for letting me share my opinion.