> For example, if someone is bitten by a dog, he or she may become anxious around dogs of all breeds and sizes While often not helpful, this doesn't seem like a brain defect. If a class of things causes you severe trauma it seems the natural response would be to recoil from that class of things in the future.
It is not a defect and it is a defect. I mean there is a big reasons behind such a response, but these reasons are often do not justify the severity of a response. Moreover bad memories could become worse with a time passing -- each act of reminding triggers an emotional response which becomes a part of memories. So it is a valuable mechanism increasing fitness and survivability, but it is not perfect. Especially it…
The issue is that the phrasing, and many peoples' mindset, seems to be that it's a trivial problem and solving it can be taken for granted; we just have to find the right trigger to enable the solution.
Generalizing from specific instances is the root of...well, isn't it the root of basically every intellectual and social problem there is? It's about as likely to have an on-off switch hidden somewhere as world peace.