New user who has 1 reputation point.He or she asked a question then other users down-vote his/her question.Can his/her reputation be minus? If not, why?
Reputation is there to give incentive and reward users. A negative reputation would be the opposite of an incentive - it would be a sort of punishment.
As someone once said -
The StackOverflow team believes that everybody's special in their own way and doesn't deserve to have a negative self-esteem (aka reputation).