The recent debate surrounding "catkiller" Fang Shang-wen (方尚文) seems to rather miss the point. The arguments center around whether tougher laws are needed to "deter" such behavior and whether animals actually merit any protection under the law. Rene Descartes believed animals had neither a soul, mind or feelings.
Since his grasp of logic was apparently rather poor, he also believed that this somehow entitled humans to abuse them, even for entertainment.
Fortunately, Descartes is better remembered for his geometry and not his philosophy. Whether or not animals are in fact capable of suffering and pain is completely irrelevant. Imagine a deranged toy manufacturer, whose hot product is a robot `pet' made from organic-looking materials which is able to precisely mimic real animal behavior -- including behaviors associated with pain. Now imagine that your next-door neighbor's yard is filled with the mangled remains of said toy pets, because his favorite hobby is to do inventive and unpleasant things to them to enjoy the (apparent) distress reactions.
Would you let this man babysit your kids?
You would, I hope, realize that he has a serious mental illness, despite the fact that the "animals" he is torturing are merely sophisticated machines.
Animal abuse is not a crime in the same way as, for example, stealing cars is a crime. It cannot be deterred with fines or prison or social ostracism because the perpetrators are often incapable of understanding that their behavior is wrong -- or rather, that there is something wrong with them.
Like Descartes, they believe that kindness and cruelty are defined by the target of those actions, and not the actor; that kindness is not kindness if it is given to the undeserving or the ungrateful, or that cruelty is not cruelty if it is inflicted on the witless and defenseless.
Prosecution, to them, is merely persecution (Fang and his weird family are genuinely bewildered by all the fuss). From a purely philosophical point of view, humans consider themselves the pinnacle of evolution and should therefore aspire to treat others well -- simply because anything less would be unbecoming for a being that likes to call itself "civilized."
From a more practical standpoint, deliberate abuse must be taken seriously, if not for the local animal population, then for the humans who need to worry about what might happen to them. In other words, Fang shouldn't be walking the streets until he's received some medical attention.
A recent report said that UK and US animal-protection laws are superior to Taiwan's. This isn't really true; although animal-protection organizations are better funded there and abusers are caught more often, Fang would have received much the same treatment under English law as he did in Taiwan.
The difference, perhaps, is that he would have also received compulsory psychiatric evaluation and monitoring.
Unfortunately, this doesn't happen in Taiwan, so a few years from now we can expect to see Fang in the newspapers again -- except this time the pictures won't be of cats, and there will be distraught parents asking why something wasn't done earlier.