I’ve been engaging in some debate on the moral merits of a vegetarian diet and in doing so I’ve found myself frequently responding to the interesting argument that runs: all things are alive, so a vegetarian diet is not morally better than an omnivorous diet. I say it is an interesting argument not because it is a good argument but because of what it reveals about our moral psychology. Actually, I think the argument is very weak, as the vegetarian is compelled to adopt their diet by the unnecessary suffering of beings, and it seems unlikely that plants suffer, but if they do then it still seems likely that flora suffer less than fauna, and as we need to consume something to survive we are justified in eating flora as it is necessary suffering, and less suffering than that done to fauna.
But what is fascinating about this argument is the manner in which it deflects moral criticism by implicating that a vegetarian diet is morally wrong too. The argument is not that both vegetarian and omnivorous diets are morally permissible, but rather that both are morally impermissible. It puts the vegetarian on the same level as the omnivore, and concludes that both diets are morally wrong — a further argument would be needed to show that both are permissible. It defends the morality of an action by going on the offense and challenging the morality of alternative actions. If one person knows that a habit of theirs is not morally permissible and that an alterative habit is morally permissible then it seems irrational for them to not change their behavior. Yet if one thinks that neither their habit nor the alternative options are morally permissible then it does not seem so irrational not to change their behavior.
Stipulating that the vegetarian is opposed to eating things that were ever alive (which is of course a misunderstanding of their view) it follows that eating food products, flora and fauna alike, would be morally impermissible, and so we could say “eating vegetables is wrong” and “eating animal is wrong”. As noted above, an omnivore might sincerely come to hold the belief “eating animals is wrong” but due to also having the belief “eating vegetables is wrong”, not stop eating animals, and not be irrational for doing so. Are our intuitions correct here? If they are, then a theoretical explanation for our intellectual observations might be that it is irrational to change from a morally impermissible action to a morally permissible action, but not irrational to change from a morally impermissible action to a different morally impermissible action.
What is going on here? It seems we have a moral belief without motivation to act accordingly – one has the belief “it is wrong to eat animals” without being motivated to stop eating animals, and this for the reason that they don’t have the belief “it is right [morally permissible] to eat plants”. Here a person is not motivated by a moral belief because they do not think that the alternative action is better. In order to be motivated by a belief that an action is wrong, it seems, at least here, we need to believe that the alternative action is right. But if this is so then it seems motivation to act on a moral belief is not internal to that belief, it depends on external factors, most importantly of which here and perhaps elsewhere, are moral judgments about the alternative actions.
The question of whether the omnivore sincerely holds the belief “it is wrong to eat animals” is of course quite pertinent here. In my discussions with the omnivores who raised this argument it wasn’t clear to me that they truly believed that it was wrong to eat animals. Still, I think it is conceptually possible to imagine an omnivore coming to have such a belief and yet being unmotivated to change their diet, and such a conceptual possibility does suggest an error in motivational internalism.