Unless the reason for a rule is understood, it is difficult to learn the rule, and it is still more difficult to apply it successfully in practice.

-George C. Crocker, Crocker's Principles of Procedure

 It can be very tempting to give the reason "because I said so"  because it's so quick and easy, but it is seldom a compelling explanation for the person who hears it.  It may make a toddler follow instructions for a brief time, but rarely does it lead to lasting change (anyone who has ever tried to get a four-year-old to stop jumping on the couch or bed has experienced this). And even more importantly, it fails to teach the child anything and does not give him or her the ability to apply the same concepts to new situations.

The same principle applies to working with adults.  You may be thinking, "well, I'd never tell someone at work to do something 'because I said so.'"  But there are plenty of other ways to convey this same message indirectly.  You may end a meeting before anyone can ask questions about a new policy.  Or, you may make a comment to "just get it done," which effectively shuts down any further dialog.  Avoiding these dogmatic situations is at the heart of what George Crocker is suggesting to us - we need to make others partners in enforcing our rules by explaining the reasoning behind them.  This helps them remember the rule itself, increases their desire to follow them, and builds employee engagement because it shows trust and openness.   

Once this is understood, the key is deciding exactly how much information to give to explain the reasoning for the rule.  Naturally, there may be items that are confidential that can't be shared in full, or technical items that would be too complex for the audience, but there is certainly something that can be shared to help everything understand the "why" behind the rules, and the effort put into finding a clear message is well worth it.