Common sense - sound and prudent judgement based on a simple perception of the situation or facts.
Many folks do not have common sense; I've met quite a few. Just the other day at the beach I met one. We head out early, it was foggy, chilly and glorious. We'd gone early enough that there were only a couple of other people with their dogs there. We ran into a guy with a spoodle (spaniel/poodle mix) and a woman with a labradoodle (labrador/poodle mix.) Both were very friendly and they had fun running around.
Then Luke spotted a dog down the beach, it was so foggy that I could not make it out perfectly. It looked like a German Shephard and it looked like it was remaining very close by the owner. The owner was not walking down the beach; she was just sort of standing there. I called to Luke so that he would not go that way; but then of course Elsa spotted the dog and was gone in a flash. It didn't look like a warm and fuzzy situation to run into, even from what I could see through the dense fog.
The woman with the doodle said to me "that's an old dog." I then remembered seeing this woman and her dog several times on the beach and wondered why she had the dog her dog there. This is an off leash beach, not a place for dogs that cannot interact with others. If you are afraid of your dog taking off then yes they could have a leash on as long as it can interact with others. Being that it is an off leash beach, other dogs are going to approach. So there I was trying to get Elsa back when I heard the lady yell at Elsa; she probably deserved it. But her old dog did not deserve being harassed by a puppy. I head there way and as I approached I could see better just how old the dog was, why would she have it on an off leash beach and risk it?
I remember quite a few years ago making the conscious decision not to bring Tilley on group walks anymore. Our poodle group got together often and at the initial greeting ritual got pretty crazy, all of the dogs were so excited to see each other that there was bounding, jumping and spinning going on. This was far too dangerous for Tilley as she had gotten frail and had vestibular disease. So not wanting her to suffer from an unintentional impact we skipped the group walks from then on. It's just common sense.
I called out to Elsa one more time and she came running, thankfully. We went off the other way to toss the ball a few more times and then head out as the fog was lifting. The woman was still there with her German Shepherd, they'd walked all of a few feet. This dog was definitely old and frail and deserved more from it's owner.