"A wise man changes his mind. A fool never will." - Spanish Proverb
This applies to parents as well. While it is very important for you as a parent of provide your child with firm rules, limits and guidelines (some parents fail miserably at this) it is also important to recognize new situations and adapt your positions accordingly. If you never allow your child to change your mind on an issue once you have taken a stand, your child will grow up feeling powerless when dealing with any authority figure. Feeling powerless when dealing with authority leads to passivity, resignation and helplessness.