We both agreed to the statement that killing human beings is morally bad. Now, the definition of a human being came up.

Ah, careful. If you've already decided that killing human beings is morally bad, you must already have a partial definition of "human being" in mind: A thing is a human being only if killing it is morally bad. Now in order to establish that a fetus is a human being, you need to first establish that killing it is morally bad.

Better to not worry about the definition of "human being" at all. Decide what makes killing adults bad, and see if it applies to fetuses. You're basically doing this already when you consider the coma patient. It would be good to make sure your friend is on the same page.

a comma patient

"coma"

We again agreed that the moment of birth can't be considered as the beginning of a human simply because there are children born prematurely and fully functional.

One argument for setting the demarcation point at the moment of birth, rather than some arbitrary point in the fetus's cognitive development, is to adopt the ideology that women are not incubators; that they have moral control over their own bodies; and that so long as the fetus is inside the womb, no third party has any right to demand that the fetus be brought to term.

I don't know whether this argument is morally compelling, but I think that it is a big mistake to ignore it completely. You can't focus exclusively on the probability of becoming human and/or history of once having been human. You also need to consider just how much sacrifice you are demanding of a person. We don't compel people to donate kidneys - perhaps we also shouldn't compel them to serve as incubators.

Before posting, please research discussions of the same topic on the blog and link to them, if they are of adequate quality. Previous post on the topic:

• Why abortion looks more okay to us than killing babies

We both agreed to the statement that killing human beings is morally bad. Now, the definition of a human being came up.

As a general guideline, if you're arguing morality, and you find yourself arguing definitions, you've taken a wrong turn.

Ethical arguments that hinge on definitions are almost always the result of trying to set the threshold for some simple, hard-and-fast binary "yes/no" rule.

Killing a comatose human frustrates the human's past desire to live.

Here's where I think my argumentation is flaved. I'd definitely not kill a coma patient (not fully human being since not thinking) whose chances of becoming a human are 10% but I'd definitely kill a fetus (also not thinking and not living on his own), whose chances of becoming a human being are greater than 10%.

So is it ok to judge our action by considering how big percentage of a human being are we switching off? It seems logical, but the consequences are strange.

Check your utility function. For any given moral dilemma, the answer is always in your utility function. Or in your preference structure to be pedantic (i.e., utility functions are certain types of preference structures. Your preference structure may or may not be a utility function.)

The abortion debate is largely one big example of a disguised query. Everyone agrees that killing humans unecessarily is wrong, then they argue over whether a fetus is a human. But all of the normativity is built into this magical word, "human." Both sides are asking "is a fetus human?" and this is the WRONG question to ask. The right question is "how much do we value a fetus?"

Furthemore, there's no reason, a priori, to assume that all of the value of a fetus/baby comes at childbirth or at conception. Looking for a point in time where something discontinuous happens to the fetus in order to determine when it obtains all of it's value needs justification in itself. It assumes away the possibility of a continuously increasing value of the fetus (in time). This may or may not be a safe assumption, but in order to really know, you need to discover your own preferences. Personally, I think it's more likely to be a (relatively) continuous function in between conception and childbirth with discontinuous jumps at those two points. There is something special about both conception and childbirth that induces a sharp increase in the value of the fetus, but there's a slower, steadier increase along the way from conception to childbirth as well. There may be a few more discontinuities as well, e.g. when the heart starts beating or the brain begins to control the body.

As for the difference between the fetus and a coma patient, consider biting the bullet that you just do value coma patients more than fetuses. There's nothing inherently wrong with that. Someone else might exclaim that your morally depraved, but that's what their utility function says, not yours.

Here's where I think my argumentation is flaved. I'd definitely not kill a coma patient (not fully human being since not thinking) whose chances of becoming a human are 10% but I'd definitely kill a fetus (also not thinking and not living on his own), whose chances of becoming a human being are greater than 10%.

This will sound horrible and get me downvoted. But not all human lives are worth exactly the same.

It would be wrong for me to kill an adult amnesia patient with no hope of recovery but I'd consider it less wrong than killing the same person sans amnesia.

When you kill the 10% chance of awaking patient you also kill all the experiences he has already had as well as the ones he will have. When you kill the 10% chance fetus you just kill the ones he will have.

I think the "will have" in both cases is not certain to happen due to other reasosn. The has had bit is certain.

Writing, not Writting; English, not english; Christian, not christian; flawed, not flaved; one "comma" still survives uncorrected.

I'd definitely not kill a coma patient (not fully human being since not thinking) whose chances of becoming a human are 10% but I'd definitely kill a fetus (also not thinking and not living on his own), whose chances of becoming a human being are greater than 10%.

I am pretty certain that I would kill a coma patient in some circumstances. If a person was expected to either kill a coma patient, or let the patient use the person's organs for nine months, I would not condemn the person for whatever decision she made.

Also note that most defenders of abortion agree that abortion is not fully acceptable during the last months of pregnancy. I certainly don't accept that there must be a single significant moment when the being's moral status is suddenly switched from nothing to full person. I don't have a definite opinion about what makes killing a person bad, but I am pretty sure that killing a morula is morally neutral.

From legal point of view, it may be necessary to define a single moment when a person gains protection against being killed, but there is no reason why this should coincide with some significant biological event. People are legally able to drink and drive and vote at the age of 18, when nothing biologically significant happens. What's wrong with abortion being legal up to third month of pregnancy or so? In fact, in many countries this is how it actually works.

My .0002 babies:

• Yes, I think it makes sense to judge our actions by their expected results, even though expected results like "shutting off life support for this coma patient leads to .1 fewer lives than keeping it on" are sometimes difficult to think clearly about.

• If futures with more human beings in them are better by your moral lights than futures with fewer human beings in them, then it similarly makes sense to judge your actions by the expected number of human beings they cause to exist in the world, all else being equal.

• More specifically, given the above it makes sense for the chances of a particular organism becoming a human being if allowed to survive to contribute to your moral valuation of allowing that organism to survive, all else being equal.

• If the "more human beings => better" term in your moral equation is sufficiently strongly weighted so as to overpower the contribution of other terms, then you can delete the phrase "all else being equal" above. I don't actually know anyone for whom this is true.

• Even given that moral weighting, it doesn't follow that "killing human beings is morally bad." For example, if the expected result of killing George is that .1 more lives are saved than if we let George live, there's at least a coherent moral argument for killing George. If 1000 more lives are saved, it's even an emotionally compelling argument.

• Again, it makes sense to me to judge actions in terms of the moral value of their expected results. In fact, that's pretty much the only way it makes sense to me to judge actions. That means I consider questions like "is choosing to become pregnant good/bad?" or "is choosing to teminate a pregnancy good/bad?" or "is killing George good/bad?" somewhat ill-formed... "good" and "bad" properly apply to the expected results of an action (and even then, only relative to the results of other actions), not to the action itself. When talking about a specific action the difference doesn't matter too much; we take the action as standing for its expected results by metonymy. When talking about a class of actions it starts to matter more.

• It's probably obvious by now that I'm a moral consequentialist. A deontologist (I know there's at least one on LW) would disagree with most of my reasoning above.

If you want to see a really... unusual... argument on the topic of abortion, you could look at the views of David Benatar, who has argued the position that it is wrong not to abort fetuses.

So is it ok to judge our action by considering how big percentage of a human being are we switching off? It seems logical, but the consequences are strange.

That, along with "intelligence" or "ability to feel pain" seems like an ad-hoc rule for moral value that may or may not correspond to the criterion of moral worth we actually use. The problem with coming up with rules like that is that once you become attached to it (by say talking about it in public, debating about it), you start extrapolating it to areas not covered by our intuitions.

I don't know what the moral indicator, but I see different people coming up with different simple moral indicators, and view that the same way I see people coming up with different religions: at most one of those can be true.

Is killing a human more bad than creating one is good? If not, everything else is irrelevant.

What exactly constitutes "becoming a human", or "killing" for that matter? An egg has a high chance of becoming a human if it's fertilized. Would refraining from fertilizing it be killing?

On the other hand, little if any of you is actually made of the original fetus. Does that mean that the fetus itself won't become a person? It's mostly food and water that becomes them.

Here's where I think my argumentation is flaved.

"Flawed", not "flaved". (Are you Chinese by any chance?)

Seems like you've come up with a moral argument that you can't find flaws in that you're rejecting because of the conclusions it leads you to.