Well killing is a bit extreme. In modern day society, it's the cons way outweigh the pros. That's on an individual level, by the way. Different killings and different causes/lead ups of course have different pros/cons.

If the situation was as was described in the opening post, I'd have no problems eating the other guy. But if you introduce a con, then it gets trickier. Like, I'd have hard time deciding of whether to eat my brother, for instance. He's a great guy, and I'd love to keep him alive. So eating him is obviously going to remove that.

But if you mean, just me going out right now and killing someone. That's far from happening. The first major con is the legal system. Which is why the legal system exists in the first place. Jail time is wasted time.

Then you get all sorts of official marks and records on you, which are spread to other people. Yet another con.

Then you get all the negative social relations because of jail time and murder. Yet another con.

In order to kill someone, you need to first obtain the materials in order to do so. That takes time, sometimes money, and whatever else goes into it. That's another con.

There's no overall point to it. Military sometimes has a purpose, as do natural animals and in the wild and such. But in modern life, there's really no point unless there is some benefit (cash, you have a grudge, etc). I personally have no reason to kill.

It's just a lot of work with little payout. So there's no reason to attempt to do it and risk punishment via various sources.

But other illegal activities, piracy for example, I do all the time. The only con to me is a slight risk and fine. And most of the time it's not even that. Maybe a message from my ISP (if they care that much). The other con is that my favorite companies will lose cash and might crash. I figure that the pros (getting free stuff) is worth it. So I do it. I support my favorite companies in other ways, whether it be buying promotional content, or advertising the brand.

It's the same reason I support legalization of recreational drugs. I don't personally use them, but I see no problem with it. It doesn't harm me or have any cons for me, so I support it. Pros are obvious. People seem to love the stuff.

As I said. Most of the things that I consider right/wrong, is merely because I've looked at the pros and cons and made a decision based on that. My "overall" choice is that I should follow the legal system (for the majority of rules) because I'd like to avoid jail time. Because that would suck. And it'd pretty much ruin every other opportunity. That's why I'm not interested in being an activist either. I see the shit they go through. Kudos to them, but I wouldn't do it.