(Thoughts that occur as I look through some of the answers and analyses of the answers in a philosophers' poll.)
How would Ayn Rand answer "the Trolley Problem"? My inclination is to think she would ask for any real-world scenario in history that comes remotely close to resembling such a scenario. She was concrete-oriented that way. In terms of general principles - not to be confused with a rationalistic "top-down" approach which takes such a scenario as a "good test" of some abstract principle that may or may not have been derived rationally and properly - her approach is indicated in "The Ethics of Emergencies." The Trolley Problem would fit the definition of an emergency situation as well as any. So what's the right answer? Is there a right answer?
Philosophers of the "mainstream" variety like to use such hypotheticals to challenge either moral theories or moral intuitions or both. What do our intuitions on this say? "Intuition" seems like a euphemism for "common sense," and common sense tends to be a highly reliable indicator of at least being on the right track. (I like to think of Aristotelian and Randian philosophy as common sense carried through consistently and to the extreme.) Common sense would say that faced with such a scenario - and the scenario stipulates that one's actions affect strangers of an indistinct age, gender, intelligence, etc. - you "do the numbers" and flip the switch (resulting in one death as opposed to five).
Now, the question of interest to philosophers is whether doing the numbers validates utilitarianism as the ruling paradigm of moral reasoning.
Isn't that a bit insane? Isn't that more than a bit insane? What kind of philosophic/epistemic methodology leads one to such a conclusion? What if utilitarianism gets its appeal mainly from applying the ethics of emergencies to normal real-world scenarios? And that gets us back to the original question: what real-world historical scenario resembles the Trolley Problem? We need a theory we can apply to the real world and not just to a hypothetical scenario that may or may not resemble the real world.
My (and Rand's, and Aristotle's) moral theory is an individualistic eudaemonism, which would fall quite squarely into the "virtue ethics" category. Eudaemonism tends not to concern itself with such questions as what to do in a Trolley Scenario, but rather with what it takes to live a good human life. So ultimately what it comes down to is what decision is constitutive of the agent's living well as a rational animal. The broad principle is covered quite well in "The Ethics of Emergencies," and the broad principle aligns very closely with a common-sense orientation toward the world. Common sense dictates, without knowing anything about the people involved, without being provided any alternative to either one or five people dying, etc., that you flip the switch and save four lives. That seems to be the reasoning a eudaemonic agent goes through in such a situation. It looks like the decision a person trying to live the best life they can would reluctantly make.
But what bearing does that have on the way a eudaemonic individual lives his life generally? We get back to the real world and ask what scenarios look like that. I'll just throw this one out there as it seems like as good a concrete as any: the decision to drop nuclear bombs on Hiroshima and Nagasaki. Here we have political leaders faced with two basic alternatives, under the assumption that the Japanese army and its leadership are all brainwashed (much like the Nazis) and won't surrender peacefully: Drop the big bad radiation-spewing bombs, or go through a protracted invasion with much greater loss of life, especially of American life. Faced with such an alternative, what do you do? The American leaders "ran the numbers" and decided it definitely wasn't worth the cost in lives, especially in American lives. The real, main issue is what got these countries into such a fucking crazy scenario to begin with. But given the craziness of the scenario, the nukes - with all their own associated horrific effects - looked like the least-worst option. It so happens that no nukes have been used in wartime since. Coincidence? It also so happens that the leading nations of the world haven't gotten themselves into such a crazy fucking situation to begin with since then. Coincidence?
(Stanley Kubrick's 1964 film Dr. Strangelove highlighted the fucking craziness of it all, and there hasn't been a nuclear showdown anything like the 1962 Cuban Missile Crisis since that time. Coincidence?)
Okay, so we have a real-world scenario that kind-of resembles the Trolley one, and best as I can tell, eudaemonistic ethics emerges essentially intact, so what do we learn from the Trolley Problem? Why do "mainstream" philosophers obsess over such things? (It so happens that those philosophers most associated with the problem, Philippa Foot and Judith Thomson, are among the best of "the mainstream," so perhaps the main upshot was to highlight the inadequacy of deontology and consequentialism as ethical theories, or maybe better yet, how incompetent but influential philosophers have used these theories in all kinds of counter-intuitive ways. Long story short, the answers these theories or their proponents are likely to give in such a situation are counter-intuitive. I don't find that to be surprising at all. These moral theories are rationalistic constructions that don't gel with common sense. Foot, however, was a virtue ethicist. Coincidence? I don't think so, seeing as how eudaemonism does everything an ethical theory is supposed to do.) Perhaps the "mainstream" obsesses on such matters because of bad philosophical methodology, i.e., bad epistemology. This would not be any surprise, seeing as how "mainstream (academic) philosophy" has become so specialized and so compartmentalized that epistemological issues hardly enter into the picture amongst the mainstream moral theorists.
We already know that to be the case when it came to the most influential mainstream moral philosopher of our times, John Rawls.
But seeing as how the Trolley Problem is, at the most fundamental root, about philosophical methodology (i.e., epistemology), how do you really answer it without doing all the appropriate background integrations to begin with. How on fucking earth do you approach any such problem (much less any other problem) without having done the appropriate background integrations (which include a high regard for common sense)? In other words, how does the mainstream of contemporary moral philosophy deliver anything but epistemic paralysis, short of becoming thoroughly familiar with proper principles of epistemology? Do these mainstream academic philosophers even really know what the word "integration" means?
Seriously, do they?
(Hint: During the course of 2 years of graduate study at what was, at the time, a leading program in moral and political philosophy, I don't think I ever heard the word "integration" once. Maybe in effect during my course in ancient philosophy given by a prominent Aristotelian-Randian, I did. Aristotle's hylomorphic theory of the soul was a big focus there, and that's basically all about integration without using the word. But it's doubtful all that many contemporary academic moral philosophers understand the epistemic implications of Aristotle's approach to the soul much less anything else. If they did, the world of academic philosophy wouldn't be mired in such a bog of shit, for one thing, and it would be all familiar with Ayn Rand's theory of concepts for another. So, no, the academic mainstream really hasn't the faintest what "integration" really means. Note: it's not the same thing as Rawslian "integration" - read: laughable attempt at reconciliation - of rational and irrational moral positions.)