That is a great approach, older men and women can still affect others. Strength of character is still strength.

I agree. Mine isn't that big, but it fits easily in my pocket so I can carry without anyone knowing I have it. I feel naked without it. I also carry a few small ones in my purse. If necessary I can put my big survival knife on my belt.

I've carried a knife with a 4 inch blade ever since I was a Boy Scout. It comforts me when I can't carry. Besides, a knife comes in handy for many tasks.

Im a rickety old guy, but I wouldn't be able to restrain myself. I might try shaming the crowd into action first by shouting something like "Are we going to let this punk get away with this? There are more of us than him!" Sometimes, the smallest incentive will get people to move. However, if this is an example of the new America, of "Millenials," I feel sorry for this country. It's lost its heart and maybe deserves its current fate.

This objectivist would intervene. I've done it before, and would do it again.

My logic:
I am a semi skilled martial artist, pretty tough and pretty strong, therefore the risk to me is modest
Yes, there is risk to me, BUT
my action would provide confidence and incentive to others (present or learning of it) to also stand up for themselves/others
This supports my objective for the world of people to be self policing in such situations
The benefit far outweighs the risk.
Logically consistent.

The world, especially the US, needs to have many indigenous white blood cells among the population, not just knowledge of a 30 minute response to 911. This reduces fear and provides freedom!

The passengers who did nothing exhibited a lack of altruism. An altruistic person would take a risk of personal injury to help the victim of the attack.

Helping someone in such distress is a secondary reason why I pack a pocket pistol is so I do not have to stand by and watch something like that.
Getting old with health issues, I'm not not fighting or grappling with any assailant even for my primary reason of self-preservation.
I'll just shoot the SOB.
Old Bama boy is also staying out of sorry places like Washington D.C. and birth state Massachusetts

I look at these people and think about the calls (here and in other places) to fight for our freedoms and rights. Fight totalitarianism and all the other isms. It's our duty. How can one think that is possible if in the face of this we have no duty to respond?

In the case of the 911 crash, people were defend-
ing their country, and unwilling to live as slaves.
But I still find the behavior in the other incident
somewhat bizarre, as there were plenty of people
who could have ganged up together on the thug and wrested the knife from him, without very
much risk to themselves.

An objectivist acts rationally understanding the context and values at stake. You must know that you can control the situation if you act. That means knowing how to overpower a probably drug infested person disarm them and then render them helpless until others get their courage and the police arrive. That's a big bit of knowledge about one's self that is necessary for action. Objectivism says be rational and act in context. You would quickly see who you could count on because of how they fled to the ends of the car. A physically confident person moves differently than a fear driven person. You sense their awareness and smoothness of motion, Think Ragnar or D;Anconia at the steel mill. If they are experienced all it takes is hand gestures to set up a coordinated response. Obviously no one was packing, too bad and no Marines on board. .

I am a large but old man and much more stupid than brave, but I am sure I would have tried o stop the killing regardless.

Others addressed this well, so I'll just raise a couple of points.

1. Re United 93, the passengers had time to establish enough rapport to collaborate on a response. These people did not.

I would have looked around for eye contact with other ablebodied men to make a silent pact to attack. I have some police background, but I'm over 70 with significant strength limitations like torn rotator cuffs. The last time I intervened in a public physical situation I completely tore my left subscap. That required two surgeries to rebuild my left rotator cuff. I realize I can no longer act like a young, strong cop. And that leads to...

2. What if the average person were armed and trained?. That would change the context in this example and on Flight UA 93.

The author is either naïve or stupid. This incident is certainly not the same as on the 911 flight. In the latter case, everyone knew they were going to die without action. On the subway, everyone knew that they might die if they intervened. In both cases, people acted to save themselves because the risk was determined to be too great if they did the opposite.

You are absolutely wrong. A selfish person (properly defined) would protect his own life first. One should weigh the danger/risk to self + the value of the other person (thus worth greater risk for those most cared for) before acting in such a case.

You'd have to hold me back. He who attacks one of my fellow citizens without provocation, attacks me in the same action. I wouldn't vouch for that knife-wielder surviving the encounter.

While I certainly do not view ethics as a matter of survival-at-any-price, I would probably avoid getting myself stabbed by a man probably stronger and more battle-tested than myself, and I wouldn't feel guilt either. We don't have a duty to help strangers when our own lives would be put in danger -- that truly would be an ethic of self-sacrifice. What we have is a prudent judgment that we must make under the circumstances. Perhaps brave knights are to be praised for their courage, but there is no need for guilt over what is essentially not a duty.

I'll agree that if I could intervene without risking my life and health, then certainly I should. If I were to hear a rape taking place outside my apartment, I should at least call the police.

I recommend reading Ayn Rand's essay "The Ethics of Emergencies", plus David Kelley's book Unrugged Individualism, to get some depth on this issue.

I'm happy with the other responses so far. I believe it is in our rational self-interest to defend the right to life for all individuals, even when it isn't our own. And it's up to our own initiative, leadership, and creativity to do it in a way that doesn't threaten our own lives or values. This is a sad case when one person with initiative, courage, and leadership would have used strength in numbers to save a life from an immoral attack.

An interesting question for an Objectivist. I think from both a gut reaction and an Objectivist position, I'd have to try to stop the attack and I'd be yelling at others to help as well. Thuggery should never be rewarded with cowardice.

But I've been there, done that, and got the coffee cup. Most Objectivist have not been tested in such a manner. For that matter, not that many men in general have experienced this type of event. But I've also seen a lot of women step into such events as well without fear, and often times to shame the men there that haven't interfered. Though a brouhaha between two men on the other hand is not to be interfered with.

You said that so much better than me. It would not be in my rational self interest to allow evil to prevail if I could do something to stop it.

An objectivist would have acted to stop the murder because to do so would be to serve his values. A truly selfish person could not have stood by and watched that happen.

I disagree with the author in the due unto others bit, and they weren't being selfish in the sense that Rand means it. Not being there, and only reading the article, I would have stepped in also. It was apparently a small knife, probably about the same size that I always carry, and there were enough people to overpower him. How many women had purses that could be swung hard, even if all it did was distract him from the attack and make him run? What if a few of the men yelled and took aggressive steps toward him? He likely would have stopped before he completed the kill. The fact that they all just stood there allowed evil to prevail.