At the beginning of a relationship…

At the beginning of a relationship, do you trust your new partner unless there is something specific to make you do otherwise, or do you withhold your trust until he or she has earned it?

My approach to any relationship is to trust a person upfront because I believe people innately are decent.  If it turns out they are not, my trust will quickly be lost and I can’t remember if there has ever been an instance when it has been earned back.