Andrew Stuttaford is entirely right here when he discusses why its a good idea to talk to Iran. The point is that you might not gain anything, in which case if the talks are done at a low level you haven't lost anything. You might though gain something in which case you have a success. Talking is a bad idea if it gives the other side a propaganda coup- I remember Blair going to Damascus and being attacked by Bashar Assad but if done properly at low levels what is the problem with it. Furthermore if its done properly with a proper arrangement in place, it can even work at higher levels. The point is that negotiations don't lose you anything, they may even gain you advantages.