We keep the tree around because of its aesthetic or productive value to us - i.e. the old maple tree is preferable (to us) over the younger. We are inclined, in this case, to preserve the "work" we've already done to raise the tree up to this point. We do not perceive the tree as conscious nor sentient.
The human, however, is, at least in our books. We care about the fact that the child has a lifetime of experiences that it has yet to experience - and we value said experiences, and most of us I think would agree that every human is reasonably entitled to experiencing the highs and lows of life.
I'm not sure if it's valid to harp on people for having different logic and/or morals when it comes to dealing with sentient subjects as opposed to not. It seems to me entirely logically consistent to treat the two differently.
However, some studies show that, depending on your definition of sentience, a baby might not fit into the category. There are many things (from memory: seeing moral consequences; some kinds of what if processes; understanding analogies) that aren't available to a person until 5-6 years old. Even trivial concepts such as the idea that an object still exists even when it's out of sight are not in the toolbox of a baby.
The original assertion is that people are being logically inconsistent by wanting to sacrifice the young tree, yet reluctant to sacrifice the young child. Based on the premise of tree non-sentience, it is entirely logically consistent that the two cases be decided differently.
The problem with tree sentience in general is that we have yet to define "think" in the context you are using it.
The baby has no value, it won't be able to help with our decision making process to get back to shore, it won't be able to solve problems we may find along the way, if we get stranded somewhere it won't be able to build shelter or find food. At that point the baby is nothing but dead weight that requires a constant amount of resources without any returns.
Also, I'd like to point out that if you make your opinion known that you plan to throw the baby overboard, everyone else is probably going to want to throw you overboard anyway.
We'll assume for the purposes of this thought experiment that the shark just wants a nibble - he'll be satisfied for sure with either one.
Also an older scientist might be past his prime and have lower expected utility for the rest of his career while still expecting high pay.
Yes, I realized this after it was too late to edit (well, I still could edit, but people have already replied, so it wouldn't be fair) - I probably should have made the doctor younger.
But in any case, it brings up the question: how young is "young enough" to prefer throwing a baby overboard to throwing a highly promising child/teenager/adult? Is there a "young enough" age for you, or would you always toss the older person, no matter how likely they were to be exceptional for the rest of their life?
Meh. Then cut off your arm and give it to him. The problem with these philosophical experiments is controlling external variables. It just can't be done.
Does utilitarianism demand total knowledge? Can't you posit a baby exception wired into your brain (by evolution, $deity, whatever), obey it, and still be an orthodox utilitarian?
But then this could just be me trying to retrospectively justify my inclination to save the baby.
The moral line is between whether you're able to kill a person ("toss out to save somebody else" - our human killer brain is good with coming out with "good/valid" reasons to kill) or not. If you're able to kill, then it is just a small technical detail whom to kill and why.
This being said, I would _never_ realistically propose this. The risk of being lynched, or at least severely handicapped socially in a critical situation are not negligible. After all, who would you rather throw, a 50 year old doctor, or a guy who just proposed throwing a baby?
An amusing article about the trolley problem is "Brain Teaser" (http://www.mindspring.com/~mfpatton/harper%27s.htm) which satirizes these ethics problems by adding an absurd number of conditions such as a busload of orphans, transplant patients about to die, a brain in a vat, and the inventor of the pop-top can.
But the baby has almost no potential. Well, that's not entirely clear...
Let me be more specific: the baby has some potential, but since it's too young, we don't know where on the Bell curve of potential it lies. Our change in expected value by throwing the baby overboard and making a brand new one is zero (at least once we casually discard the mother's grief, and the general distaste for throwing babies to sharks :) ).
We have to evaluate this against throwing the doctor overboard and starting with a fresh baby - the doctor has already proven that he's somewhere near the top of the Bell curve, so in order to figure out the utility of that trade, we need to consider how much he's likely to accomplish over the rest of his life as compared to what an average baby will accomplish during theirs.
Perhaps making the doctor 50 years old was a bit much, as it does raise questions about how much life he actually has left, and whether the (say) 20 years that he'll actually be practicing can be considered as useful as the 80 years the newborn has in front of it. I think there's still an argument to be made that 20 years of work from a highly qualified researcher is worth "more" than an average lifetime lived by an average person, but it's not crystal clear.
Suppose I'd made the doctor a brilliant 25 year old making great strides in cancer research - would that make a difference to you?
A bit of indulgent nit-pickery: My first inclination would just be to move the younger tree. It wouldn't add significant costs to the investment of building a new road.
1. The tree issue is a false choice. Maybe I can just dig a hole and transplant the smaller one; perhaps I can modify my needs.
2a. From a callously practical point of view, the 50 year old doctor-professor will make a much larger and more satisfying meal for the hungry shark than the baby, which won't be much more than an appetizer.
Of course, we have to ask why we're putting the interest of humanity in general on such a pedestal, considering that society has yet to dispatch a rescue craft. Maybe we should keep the doctor around to treat the victims of future shark attacks or dehydration; in this sense 'society' looms only as large as our future life expectancy after the shark has gone. Then again, the doctor is heavier than the baby, and will consume a greater amount of food...
2b. Everyone else in this boat must be a Nobel prize winner or something if the successful medical researcher is the most disposable person after the baby. It's another false choice, in that it bolsters the hearer's ego while simultaneously limiting their choices - this exercise doesn't cater for the suggestion that one might sacrifice themselves to save both doctor and baby, for example - although the sad fact is that few people would, so in that sense it's accurately predicated on humans' general selfishness.
However, as a false choice it's dangerously seductive, and politicians work this one (or an inverted version) all the time: "We can't increase the debt (lifeboat)! Should we give a tax cut to the rich so they can create jobs (proven success) or waste it on giving welfare to bums (unknown outcome)?" or alternatively "My opponent is soft on crime. Are we going to get tough on criminals (proven bad) now or wait for some other innocent to die (unknown probability)?" You can construct endless variations on this, regardless of your political leanings: just stick with the formula of "Time is running out - do you want distasteful alternative A or repulsive alternative B?" and just tailor your argument to the known biases of whatever group you are addressing.
Underlying this argument is the implicit threat that if you don't make a choice, you'll be chosen instead. Republicans hint that not voting for the wealthy folks' interests could cause them to cut your job, Democrats murmur that the rich might find themselves sinners in the hands of an angry mob. Broad arguments that suggest joint stakes and responsibility (eg raise some taxes and cut some spending) tend to upset everyone, which is why they're only ever offered by politicians who are leaving office anyway.
2c. Value of the baby is unpredictable. Certainly if you take 100 babies and measure something (anything) about them now or in the future, you'll get a nice Gaussian distribution. But an individual baby's future is no more predictable than an individual roll of a dice. You are not any more likely to throw a 3 or a 4 than a 1 or a 6 or a 2 or a 5, even though the average of 100 throws will converge on a value of 3.5. Evaluating the probability in light of the doctor being a '6' is seductive, but only as long as you keep sidestepping the question of who else is in this boat that makes the doctor seem 2nd-most disposable. If the baby is the child of two world-class geniuses (neither of whom we would throw out before the doctor), then the probability of its future utility is high.
We could also wonder about what the average person will be capable of in 50 years' time thanks to technology, vs. the skilled person of today. Their relative utility to society then may be lower than that of the doctor to society today, but it might be larger in absolute terms. I am particularly wary of assuming the doctor's future utility over 25 years of natural life will exceed that of the average person's 50 years.
But the unpredictability of the individual is the more important factor. Suppose there are 100 lifeboats, none of which know about the others. If all 100 follow your advice and toss the babies, those with excellent future potential will be lost as surely as those of average or lesser potential.
2d. But the big issue here is the moral question, and here we have more rational responses than 'it's a baby, it feels so wrong!' Factors of weight, food consumption, shark appetite and life outcome probabilities aside, the basic argument against such a course is the defenseless nature of the baby; s/he cannot volunteer, acquiesce or even resist being thrown to the hungry shark the way the 50 year old doctor can, and this gives us an excellent reason to refuse the idea.
Is it because of a moral obligation towards defenseless beings? Sort of, but it's not rooted in any abstract philosophy. It's rooted in our self-interest: if we are in favor of sacrificing the defenseless, then then we are advertising our utility calculus to others in the boat. True, we are not sacrificing the baby because of its defenselessness, but we are not letting the fact mitigate against the utility function either. In a future round, we might throw out someone who's asleep because their wakeful utility is similarly imponderable; that increases the danger for all, since all need to sleep; nor can we exclude ourselves, since we began with the position that circumstances brook no delay.
Even if none of us sleep, or more sharks will arrive before we can, revealing our utility calculus allows everyone else to model it for themselves in relation to everyone else. Anyone expecting to be on the wrong end of a future comparison - the doctor/professor, for example - has an enormous incentive to throw us overboard first. Such a person can make a rather compelling argument that 'after me, you're next' to everyone whose assessed utility would be lower than our own; only those for whose survival we are willing to sacrifice ourselves have an incentive to let us remain. We have already demonstrated that we consider ourselves to be at least two steps away from being expendable simply by proposing the baby go overboard; on a practical level we might expect the mother to vote the interests of her baby, and so be similarly expendable to the extent that we consider her objections to increase the risk for the whole group.
On the other hand, if we argue for the survival of the baby, we are advertising our unwillingness to make decisions about unknowables and to defend the vulnerable, an attractive quality to everyone on the boat who is not fully assured of their own survival and social utility. Given the prevalence and success fo tit-for-tat strategies in iterated prisoner's dilemma games, it's probably in our interest to identify ourselves as cooperators rather than defectors. I say probably since there's always the possibility of being on a boat full of defectors...in which case it might be better to take one's chances with the shark, who is at least honest about his intentions.
If this seems a rather involved reply, it's because I've thought about this in more than purely hypothetical terms. A day after her birth, my wife was taken aboard a ship which was part of a refugee convoy of 8 vessels. There was a storm on the second or third night of the journey, and 6 of the boats sank, with no survivors. Besides the horrifying experience my in-laws endured, I'd say she outscores me on a social utility scale too.
On reflection, perhaps a better reframing of this thought experiment (to avoid many of the issues that others have brought up) would be that a murderer has broken into your house and tied you up, along with a baby and a highly accomplished but relatively young person, and offers you the choice of which one of the others he's going to kill, along with a credible assurance that he'll kill all of you if you don't choose one (and you're not allowed to pick yourself, just because), and he'll really let the remaining two of you free once you've made a choice. Further, you're not allowed to discuss with the others, so there's no opportunity for anyone to sacrifice themselves.
You need to build a driveway up to your new house, and there are two possible routes, each one with a single maple tree in the way. One of the trees is very old, but quite healthy, standing at least 50 feet high. The other was just planted a few months ago, so is still quite small.
You're not the one that's going to cut the trees down, and the cost to do so will be the same in both cases (let's say that the higher cost to cut down the bigger tree is offset by the fact that the person cutting it down wants the wood for himself) - which tree do you cut down, and why?
Now, this doesn't seem like a moral issue. Almost everyone would cut down the smaller tree, for several reasons: it would take less time to grow a new one of the same size, we wouldn't be destroying as much previous "work", etc. Very logical, can't really argue with it.
But I lied. When I said "maple tree", what I really meant was "human", and when I said "you need to build a path to your house," what I really meant was "we're all in a flimsy lifeboat, there's a nasty shark circling, and it wants it some tasty human gubbins[1], so we either need to toss overboard the 50 year old award winning medical research doctor with a loving family of six waiting for him at home, or a newborn baby. Or else we all die!"
[Edit: As I pointed out in response to some of the comments, I probably should have made the doctor younger, to avoid questions about whether he's already used up most of his potential. I'd encourage you to think about what age he'd need to be to change your decision...]
Anyone here actually willing to stand up and say they'd toss the baby? Because from a pure utilitarian point of view, it's the logical thing to do - a newborn baby is a roll of the dice, likely to turn out as a completely average adult, with zero expected value above and beyond any other newborn baby that the same couple has, so they might as well just make another one. OTOH the professor has proven himself to be near the top of the usefulness curve, and the expected value of his remaining years is likely far greater than that of the newborn, even after we factor in the mother's grief over losing her baby.
It's a rare person that would actually make the choice to toss the baby - I certainly don't think I could, but I can't really pin down my logic to anything more compelling (in a rational sense) than "But it's a baby, for God's sake, it just feels so wrong!"
[1]: A strained extension of the term "gubbins" (http://www.thefreedictionary.com/gubbins) outside its usual meaning? Perhaps. But screw it, "gubbins" just sound like they would be so damned tasty, I stand firmly behind my use of the word.