being consostant, well it should not matter if he's allowed one day to do >>something and the next not too. Aggressive behavior should not be his >>reaction.
Dogs are not people,and they don't think/rationalize/understand as people do. Consistency IS KEY if you want well-behaved dogs. They need to know their boundaries, and those boundaries cannot change from day to day or you will not get a well-balanced dog. You'll get a dog that will always question its boundaries because he can't be sure of what they are.
If you, as leader, cannot be sure of what the acceptable perameters of behavior should be – ie letting him do one thing one day but not the next -- you will send the message that YOU are confused, and may very well wind up with a dog that begins to think, "SOMEbody needs to be the leader; If you can't lead, I will", and he will begin to attempt to make the rules.
Just my .02.
The last remark ("SOMEbody needs to be the leader; If you can't lead, I will", and he will begin to attempt to make the rules.) is totally on the MARK… they do and will do this.... without a doubt.... It is not like you can talk and "reason" with your pet... obviously... so the only thing you really can do is teach by example and consistant ways. And dogs will pick up on your fear even if you don't think you are showing it...
Here is an example... I have right now 4 Basenjis and have had 5 at one time. My one girl, Mickii has always felt it was her right to sit at the kitchen table in one of the chairs... she doesn't take anything, but watches us eat... (and yes, we should not let this behavior happen, but we do, it is pretty cute)... HOWEVER, none of the others have ever tried it... nor do we let them.. and they understand for whatever reason, she is permitted to do this and they are not... and it has never been a problem. But we are consistant with the fact one can do this, the rest can't. My Basenjis also know the leave it command and they will give up anything they have in their mouths without complaining... this again like all it a learn behavior..