There is no legal system which simply rules self-defense out of order as a justification. And why do we use the word justification? Because now this is a deliberate harm that we're inflicting on somebody and we're saying that if we had to do it over again, we'd do it exactly the same thing. If it were an excuse, "I'm sorry I slipped and I hurt him," and it happened a second time, would you say, "Gee, I slipped the first time, I'm gonna make sure I slip the second time." No. What you're not gonna do is do this, so you want to have strong justification for essentially taking after somebody else. And the alternative is if you cannot protect yourself, then this fellow is going to be able to maim and to kill you. You will now have a cause against action against him for a deliberate harm. But if you're dead or seriously wounded it's not gonna do you much good if he turns out to be insolvent and leave the country it's not gonna do you much good. So essentially what we say is, if somebody uses force against you, you may use force to repel him, which is exactly the phrase that the Romans used to deal with this particular situation. And they did so correctly under the circumstance. Well and then there's the next particular question, is, once something is done in self-defense, is that the end of the matter? Or, in fact, are there some limitations on the use of self-defense? And the answer to that question, again, has to be perfectly clear. You cannot use self-defense as an opportunity to slaughter the innocent. One of the concerns that you raise is that is the force that you're using excessive relative to the need at hand? And so if somebody's attacking you and he's old and he's feeble, and you could simply take the staff out of his arm before he gives you harm and you say, "Sorry, I'm not gonna do that" and what you do is you just take a maximum blow and darn near kill the fella, that's excessive relative to the risk in question. And, by and large, the use of force is a privilege that we give to you, but it's narrowly construed because we don't want the force to constantly expand over and over again. There's a place for strict liability with strangers, there are places with negligence when you're dealing with torts like medical malpractice in some cases, and then there are intentional harms, when you start to deal with deliberate killings, for which there can be justifications. So all the pieces start to fit together if you learn how to do it. Now, it's interesting, when the Romans did this they were very good in terms of their basic intuitions about the way in which the system was organized, but they never formalized it in that particular way. But what happens is you can formulate it in that way, and it turns out at this point the use of language is completely natural, and it conforms with the way in which everybody speaks and thinks about it. And you start from the single isolated incident in which the only fact that you know is that one person hit another, and by the time you're done you've got these civil code regulating officers as part of the same thing. This is important because we understand that police brutality is an issue that you really have to worry about and so forth. And if you can figure out why it is that officers are subject to special duties, it's going to change the way and this particular cycle is going to start to work.