It's certainly something one should be prepared to do. I don't expect to ever have to use a firearm defending myself or my family, but I am prepared to do so if I must. What you haven't yet said anything about is how to get from here to there: how do you create a society of humans in which self defense, even lethal self defense, is simply never necessary?

The question is, I think, whether that decrease in reliability is an acceptable tradeoff for the increase in safety gained due to only the owner being able to fire it.

If I'm already down, or not at home when a break in comes, I want my wife or my sons able to fire the weapon. And at the point that the safety has to be complex enough to know multiple biometric signatures, it will have a higher than acceptable failure rate. Even the single signature devices would likely be more failure prone than acceptable. Especially since I can clear a jam and keep going. How do I override a biometric sensor failure? By design, being able to do that would be a flaw.

I can understand the comfort thing, but at some point we have to decide either that people are so dangerous that they must be removed from the population, or that we have punished them enough and need to let them alone. The alternative is that the state gets to persecute and hound people forever, once convicted, continually piling on new punishments without court action, merely to assuage people's desire to "do something." And any time there are crimes that are so stigmatized (terrorism and "sex crimes" being the current boogymen) that anything can be done to punish the offenders, the natural tendency is to expand the original, horrible crimes beyond all recognition. It's the same thing as calling a handgun a "weapon of mass destruction," which originally meant chemical, nuclear and biological weapons that, when used as intended, could kill thousands at a single use. I simply think it's a bad idea to turn over to government the ability to persecute people indefinitely and infinitely, because that power will always be abused, and eventually I (or you) will be the victims of that abuse.

I don't think you know what a free market is. The bandwidth market in the US is heavily, heavily government regulated.

Wikipedia's list of defensive gun uses. Granted, I didn't double-check the info with other sources. I chose those two specific incidents because I remember having heard about them at the time.

Crazy people? Tell it to the person in Milwaukee who, on November 21, used his carry weapon to defend himself in a hair salon. Two men knocked, were let in by a customer, then one of the men pulled a gun and aimed it at the customer, who knocked it away and then used his own gun to kill his attacker and wound the attacker's accomplice. Or tell it to the 12 year old Oklahoma girl a couple of months ago, who used the family handgun to defend herself against a home intruder whose history included kidnapping a girl.

What qualifies as actually needing them, though? Most people who use guns in self defense are not expecting to need them at the time that they do. Such regulations as you propose simply make it too hard to defend one's self and one's family/property. In particular, such regulations tend to lead to armed politicians (Dianne Feinstein has a CCW, for instance, from a place that grants almost none of those) and unarmed subjects.

My understanding is that Lanza's rifle was left in the car. He only used pistols in the shooting. So in what way does banning semi-automatic rifles help prevent such acts, even presuming it could be successfully done and the existing semi-automatic rifles removed from circulation, which is doubtful?

Well, since any firearm can be used to shoot people dead, let's just talk about how easy it is to buy any firearm. For most firearms for most people in most places, fairly easy. For any firearms for any person with a criminal background or mental illness (to a much lesser extent, as this is usually not reported), pretty difficult to get one legally, but no more difficult to get one illegally than anywhere else. For certain types of firearms (automatic weapons, for example, or crew served weapons), it ranges from very difficult to impossible (legally) for anyone. For certain places, such as Chicago, NYC or Washington DC, it's pretty hard for anyone to get any weapon. Of course, those are also the places with the highest gun violence rates. Odd, that.

Of course, much of that additional time and expense is regulatory and environmental, and of that, much of it is unnecessary from a safety standpoint. In other words, making cheap (relatively), safe nuclear plants is more of a policy problem than a technology or resources problem.

I think you have to separate device and application. If a single device could contain the necessary sensors for all of those things, without a cost premium over, say, an iPhone or top-of-the-line Android phone from today, then why not? The whole reason that current cell phones are so powerful is not the processor, but the array of sensors they contain. It is those sensors that enable things like overlaying data on the world around you, and measuring (approximately) objects at a distance, and acting as a decibel meter, and acting as a level, and all kinds of other things. Is an iPhone going to be the best level for professional work? No, of course not, but it's good enough if I want to check if my new stove is adjusted correctly. Is it going to be a good enough theodolite for precision surveying? No, of course not, but it's good enough to let me figure out how much wood I need to get to build a fence without walking the whole border of the area being fenced.

Today, we already have all but two of the sensors that would be required for the applications you posit. (We lack thermometers and chemical analysis sensors.) As far as reducing false alarms to zero, that is of course impossible without introducing a lot of error in the other direction. (Google type 1 and type 2 errors.) And the sensitivity of the sensors is of course subject to the same problem. (Heartbeats are very, very, very low signals and would be lost in the noise from any distance, so getting those would introduce a lot of false positives.) And writing the apps to do all the things you want, even with real-world accuracy, is not going to be trivial. On the other hand, once the sensors are there, someone will undoubtedly try it.

In other words, your pie-in-the-sky set of examples is really not that far out from what is already possible, modulo the problem of balancing false negatives against false positives.

South Korea in the 1970s was an oppressive capitalist dictatorship (specifically, a right-wing, military one).

Sorry Mitt, but corporations ain't people.

A long line of court cases disagree with you, and for very good reasons. (Including, for example, the ability to legally enter binding contracts.)

China is an interesting problem, and I don't just mean geopolitically. On the one hand, China indisputably has been making incredible strides on applied science and engineering in space and in military matters, as well as economic progress and progress in controlling diseases. On the other hand, they've also lied through their teeth about each of these things, and so it's very hard to trust Chinese assertions without independent verification. Thinking about how far China has come since beginning liberalization just a scant couple of decades ago, the potential is enormous, and overall likely quite positive for mankind as a whole. In order to get there, though, China's self-confidence will have to improve to allow them to admit mistakes, and to get over some of the racial tics they have. I think, too, that it's likely that somewhere in the next thirty years, the Communist Party will lose its monopoly on power. That has to happen as they transition to a relatively free market, which is a path they are already on. In essence, I see China now as basically S. Korea in the 1970s, in political and socio-economic terms. Once they get to where S. Korea was in the 1990s, it's going to be amazing to see what China can do.

Who wouldn't want to carry around a miniature chemical analysis lab? On the other hand, if the phone starts transmitting smell, that would be bad. Just think about the applications for goatse alone.