One often hears the claim that animals who kill and such, are not in fact evil. The typical example is that of a lion or a tiger that kills a prey. The argument is more or less that the animal acts instinctively in order to survive and thus we cannot fault it for killing a prey. It must eat meat to live, therefore it is forced to do so. End of story.
This argument has two parts. There's the instinctive part, i.e. that the animal just acts, without thinking too deeply about it, hence it is not evil. Then there's the necessity part, i.e. it has to eat meat to survive.
Both parts sound suspect to me. On the instinctive part, ... well, many humans who commit evil acts often do so instinctively, because it is part of their innate evil nature to do so. Surely just because something is instinctive, doesn't mean one is absolved from responsibility. In fact, to be evil means precisely that one has evil instincts. Nobody becomes evil by thinking philosophically a posteriori about ethical paradigms and theories and coming up with the most evil one. People are evil instinctively. So this part of the argument seems of no use.
The second part is equally confusing. So just because you "have" to do something in order to survive, then all bets are off? You can do whatever you want, just because you "have" to? So if I took a person, put a bullet to their head, and said I'd kill them unless they pressed a button which would destroy all other life in the Universe, then if this person pressed that button, they would not be evil? They would be exempt from responsibility, just because they "had" to do it to survive? I'm sure some Objectivists ascribe to such a philosophy, but surely most well-functioning humans find this approach to ethics completely absurd.
To conclude, my question is, what actually is a good argument for why animals are not evil (because I, as most others, also intuitively think that animals are not "really" evil, so a better argument than the above must exist).