The bottom line…
Example using a feeding scenario because it is simple and easy to correct and it applies to the majority of discipline issues that come up…
We feed the pup and it growls and hackles up…give it a good tap on the head always keeping your cool…the pup will know if your doing it with anger…
Keep messing with the food bowl,and the pup growls again… give a harder tap on the head…keep working with the feed bowl or something close to the food bowl and repeat the process until the pup wags its tail…only at that time you pet the pup…repeat daily until he totally gets the hang of it…
The idea is for the pup to get the message…and not only to get the message but for the pup to remain confident and trusting around you…when you can do that you will have a better relationship with the pup and eventually, the dog that it will become…
Another thing…no self respecting dog will take excessive discipline…choose how you discipline wisely…usually, you can discipline most any dog you own as long as it has a way to retreat…
In my yard I have done lots of correcting…I have learned that when correcting they will circle back to me and lick my hand, I call it asking for forgiveness…at least that is how I see it and it also builds trust when I accept their apology…
Reuben that is all fine and dandy but that ship has already sailed for taps to correct aggression issues now. This is a grown dog baring teeth over things he doesn't like. And every time another issue happens and he gets away with it, it just reinforces it more in the dog. At this point there are only three ways to deal with it, and only the last two would be viable to me. One is he could just ignore it and or do his best to not get in those situations with the dog and hope none of his loved ones do either. Two cull the dog. Or three do the work to break the behavior. Watch how a professional trainer breaks this behavior in a grown dog, it takes work, commitment, and consistency and depending on how bad it actually is at this point it might be more than most regular dogs owners are willing to do or can do.
Also if I raised them then I can discipline them whether they have a way to retreat or not and if I couldn't they wouldn't be here long. I agree there are always limits but if you are a good handler then you shouldn't need to make many "hard" corrections and even those should be done intelligently and within reason. Association is everything when it comes to dog training, so it's always good to keep that in mind with all of your interactions with your dogs. This is all just my opinion so take it for what its worth.