But there’s only one reason to be vegan: the other reasons may buttress it, but don’t, in themselves, constitute a reason for veganism.
Why is this?
First, because there’s a definition of veganism, however imperfect, that sets out what veganism is:
Veganism is a philosophy and way of living which seeks to exclude, as far as is possible and practicable, all forms of exploitation of, and cruelty to, animals for food, clothing or any other purpose.
In other words, veganism is defined in terms of animal use.
There’s no mention of being vegan for environmental or health reasons.
The definition is clear. While people may adopt vegan diets for environmental or health reasons, those reasons don’t qualify them as vegans.
Further, the environment, health, and whatever other reasons people have for adopting vegan diets are secondary to the issue of animal use.
Why? Because animal use directly bears on the ultimate value for animals: their lives.
Any acts that are detrimental to them—for example, being confined, having body parts cut off, being made pregnant, having offspring taken away—are degrees of evil, and killling them is the full realisation of this.
This is the same for all animals, humans and others: life is their ultimate value, and deprivation of their liberty and violence are levels of evil.
What’s more, having life as a human is essential to value things as a human.
You can’t value things as a human if you don’t have life as a human. For humans to value food, cars and housing, they have to be alive. The same applies to other animals for what they value.
The Arbiter of Value
Who is the arbiter of value? Someone else’s life is not my ultimate value. It may be a value, but not my ultimate value.
The arbiter of my ultimate value is me. Likewise, the arbiter of other animals’ ultimate value isn’t us: it’s them, the individuals who are responsible for their lives.
When we judge for them, we take their ultimate value by force. We take what we have no right to, their most precious possessions: their lives.
Just as i don’t value your life the most, we, as humans, don’t value other animals’ lives the most. They value their lives the most.
Justice is moral balancing: see the scales of justice. If people take take from others, rather than peacefully trade with them, they disturb the scales, and those who’ve been robbed have a right to justice (to restore the balance—at least partially).
The environment and health
People that adopt a vegan diet for environmental reasons are only committed to the environment, not the lives of other animals.
The positions they hold are therefore constantly open to revision if arguments can persuade them that animal use is a good thing, or a good thing given specific circumstances (which is far easier).
For example, they might believe that intensive farming of cows, pigs and chickens damages the environment, but accept the idea of ‘environmentally aware’ animal use and hunting.
Likewise, people that adopt a vegan diet purely for health reasons only have a commitment to their own physical health, not to the lives of other animals.
As such, they have no reason to avoid clothes and other embodiments of animal use. They might, for instance, wear shoes and belts made of leather, or suits made of wool.
The environment and health are important, and also have a bearing on the quality of life, but are generally more removed and often indirect.
To the extent damage to the environment means direct harm to animals that live in it, then it, too, has a direct relation to veganism. However humans often don’t think about the environment in these terms.
What they typically mean when they talk about the environmental benefits of veganism, are the benefits that will result for humans.
Of course a healthy nonhuman animal population is desirable too, and may indicate a threat to human populations, but the environmentalist’s concern is with the species, the group rather than the individual.
However it’s not the group that experiences the results first hand when animals are hurt or killed.
While humans also often talk about themselves in terms of groups, and government is based on the power given to groups (the majority versus the minority), in terms of the effects on groups it’s not the groups that suffer, it’s individuals.
The standard that applies to humans and other animals, then, is their lives, and the only path to veganism is a recognition of this.