It is one thing to have stated in the ops manual that forward slips in our fleet are prohibited, and another thing to give the reason why. I am very skeptical of companies that keep their decision making process hidden. I have flown for enough carriers to know that not all procedures were borne of enlightened knowledgeable professionals. When I was in fourth grade, the comment ‘because I said so’ held some credence; now such a statement is met with an acerbic demeaning comment. It is much more effective to state the reasons behind the policy, people then are more likely to be compliant. A statement such as ‘forward slips in our fleet are prohibited as it has been documented in Boeing study 249-7981 that such maneuvers lead to premature failure of the main fin spar.’