> Most people would not say it is unethical to take them off of life support even if it's basically equivalent to killing them.

Now hold your horses there. There are huge numbers of people, probably millions, who feel morally very righteous that it is unethical and immoral to take somebody off of life support regardless of brain activity.

The axiom they've built their moral structure on is not "sentience is sacred" but "life is sacred", which strictly speaking is a stronger test than any Vegan is willing to adhere to. Strictly speaking, by that test, a Vegan is a practitioner of vast, premeditated plant killings on a vast scale. (let's not let the impossible forced hypocrisy of the axiom get in the way of a good discussion)

I don't agree with one any more than I agree with the other. The problem is not a matter of degree, but a matter of definition. A Vegan doesn't get to claim "sentience is sacred", build up a moral framework around that and then push it on anybody any more than the Rabbi down the street gets to tell me that I shouldn't mix fabrics because it's an abomination to God or the Minister in that weird Lutheran church down the road that believes that women shouldn't wear pants because it's also specifically abominable (Deuteronomy 22:5) or my friend the Imam gets to lecture me on what the Koran says about alcohol.

Even if the animal is sentinel and can feel pain, what's the problem of killing and eating them? The reason certain behaviours are considered moral/ ethical and are set as a standard is to make sure we (human) can have a reasonable life among one another, and not because the behaviour itself is intrinsically good. A lot of the time, something is immoral because it leads us into a rat race with no winner.

I think the main point I'm trying to make is that I'd love to see a concrete philosophical explanation on many of vegan-related stuffs. But instead, most of the time it's just pseudoscience and empty big words :(.

Are you suggesting that morality has no purpose other than to provide a civilized society? That's one view on morality, but it's not that common nowadays.

To suggest that you shouldn't harm a neighbor solely so that others won't harm you is a very selfish proposition. This is an anemic view on morality and altruism in any modern society. From an evolutionary standpoint, altruism and morality serve merely as constructs and contracts to enable a functioning society, but from a psychological standpoint they're something far greater.

>The reason certain behaviours are considered moral/ ethical and are set as a standard is to make sure we (human) can have a reasonable life among one another, and not because the behaviour itself is intrinsically good.

Ok, then what happens if you decide a certain person or certain group no longer reasonably belongs in the category of "one another"? For example, how some Sunnis view Shiites, and how Hutus view Tutsis. That group is no longer seen as a vital part of civilization and can be treated in any way at all, because behavior cannot be intrinsically good or bad.

>I think the main point I'm trying to make is that I'd love to see a concrete philosophical explanation on many of vegan-related stuffs.

If you want one example of such a philosophical explanation, look at utilitarianism. There are countless other moral philosophies which can be used to argue that "intrinsically good" behavior is a thing to strive for, even if it may be applied with certain nuances.

It may be debatable whether moral vegetarianism actually has the desired effect of a utilitarian standpoint (not eating meat may not necessarily reduce the number of animals killed each year for food), but it is ludicrous to argue that morality plays no role in a vegetarian or vegan's desired end goal of reducing animal suffering and death.

Just to be nitpicking, I said "functional society", not "civilized society". Although the distinction make no effect on your argument.

>Are you suggesting that morality has no purpose other than to provide a civilized society? That's one view on morality, but it's not that common nowadays.

Yes, that's what I meant (roughly). And while your example (don't harm other so you won't be harmed) sounds selfish, how about "help others in needs so you will be helped in time of need" sounds? To quote Wikipedia: "Morality can be a body of standards or principles derived from a code of conduct from a particular philosophy, religion, culture, etc., or it can derive from a standard that a person believes should be universal.". It does not necessary have to be because people are selfish, but because there are many many possible behaviors, and a universal standard (morals) allow us to know what to expect. The complexity of dealing with a large group of people (society) can get really messy real quick, just because of the sheer number of possible possibilities . That's also why many people believes that when it comes to two adult with sounded mind dealing directly with each other, any thing goes.

I'm well aware of utilitarianism, and that's actually (partly) where I got the idea of moral standard as a basis for a functional society, but I digress. It seems like the difference between your and my argument was how we tallied up the happiness sum. I draw the line at "being human", and you have a bigger one that encompasses "sentient being".

> Ok, then what happens if you decide a certain person or certain group no longer reasonably belongs in the category of "one another"? For example, how some Sunnis view Shiites, and how Hutus view Tutsis. That group is no longer seen as a vital part of civilization and can be treated in any way at all, because behavior cannot be intrinsically good or bad.

I was about to say that that there is no difference between, let's say Sunnies and Shiites, except their belief, in the sense that except for historical accident, an eternal war between the two won't end. But I just realized where that argument would lead to (and I don't like that). I guess I will have to think a bit more on vegan-ism :-)

Non-religious moral philosophies, at their core, do generally try to optimize for reducing harm and promoting helpfulness wherever possible.

Even if one does not subscribe to a specific moral framework, or a group of people subscribe to different ones, there are still some activities that they can agree are immoral. That's why it's okay for vegetarians/vegans to think that something is wrong even if they may not have developed it in the context of an existing moral philosophy. To say that something is immoral is merely to say that "I have subjective reason to believe that [something] is causing more unnecessary harm than good for other lifeforms".

I wouldn't lump all non-religious moral philosophies into the same group like that.

There are plenty that do not optimize for reducing harm or promoting helpfulness. Many seek to ensure fairness or equality. Others legitimize strength. Most of the ones I'm aware of set humans as preeiminent to the moral construct and seek to find ways to maximize the human condition.

FYI, Nietzsche was the king of non-religious philosophers in the early 20th century and was interested in neither of those things.

Rand's Objectivism is probably the second best known and it too has no interest in either of those things.

Ultimately the problem is that "morality" as practiced generally comes from some kind of religious backing. "Don't mix fabrics because God said so" and boom, it is immoral to mix fabrics.

This was an easy crutch for people to use for a long time because it saved them the difficulty of actually thinking about things.

Modern social movements away from religion as a basis for morality has put this kind of lazy thinking into a tailspin. Humans have only ever been able to define morality as having some kind of immovable axiomatic underpinning of the kind religion likes to provide. But if religion is out, and we still want to be moral, what do we underpin it with?

If we say "Science" than Veganism is right out, as it's scientifically proven to not be an optimal diet. And sentience, while interesting, holds no more moral preservation requirements in science as does maintaining an environmental temperature close to absolute zero.

It seems the sad answer is that people arbitrarily embrace some new axiom and then define their morality on top of it. Lazy people just copy this defined morality and now you end up with "angels on the head of a pin" internet fights like "how sentient does an organism have to be...?" or "what's the most free license software should morally be distributed under?" or whatever the nonsense debate du jour is.

Problematically, like all new converts, people who've embraced their new religion want to tell everybody about it, and chastise all the unconverted for their immoral unclean ways.

The truth is, the guiding notion of morals have become antiquated, but humans have resisted coming up with some other guiding framework that doesn't require mindless adherence to some arbitrary axiom.

For my money, if I had a gun to my head and had to choose an axiom to build a moral framework off of, I'd go with "ensure that survival, propagation and continued forward evolution of the species".