Just because we all agree with something does it make it right?

Studying Ethics in TOK looking at the ten commandments all of us agree on thou shalt not kill. But different societies have different laws . I couldn’t remember which country it was but there is a country where if a man cheats on his wife she is legally allowed to kill her husband as long as she uses her bare hands. how strange? How do we know when we have done something wrong? – because we feel bad or because it is not allowed and we fear the consequences. Ten commandments affect the safety of community. is something morally wrong because the wider majority believe so.  However some commandments can be countered. this ties into whether something is justified or not. If someone was to punch you in the face wouldn’t it be justified to punch them back. This is often the excuse parents face when dealing with younger children. Parent:why did you do that? Child: because he started it OR because he did it to me first! Aren’t there times when it is alright to tell lies? for example to keep a surprise. This all ties into conscience and as justin timberlake’s song says – ‘what goes around comes back around?’  and karma. There are times when we decide to ignore our conscience perhaps when we are particularly angry or vengeful our actions take on an impulsive quality. People with different character traits , with varying degrees of difficulty may choose to ignore their conscience. We are all selfish and seem to act for personal gain and thus provokes ideas that we don’t do things to others which we wouldn’t want done to us.