Veganism is an ethical position – the idea that we extend moral concern to other species. Simply put, we should want other animals to be free and in charge of their own lives without being treated badly by us, as much as is possible. These are, if you like, our moral duties to them.

As I have suggested elsewhere, these duties mirror the duties we have to other people as explained in the UN Universal Declaration of Human Rights. We can therefore say that we should treat other animals as though they have the same three fundamental rights as expressed in Articles 3-5 of the Declaration:

• The right to life and liberty (that is, to be in charge of their own lives and not to be exploited)
• The right not to be held in slavery or servitude (that is, not to be owned and used as a commodity)
• The right not to be subjected to torture or to cruel, inhuman or degrading treatment or punishment (that is, not to be harmed unnecessarily)

These three principles should govern our relationship with other species. As a consequence, the moral case for not farming animals like cows and pigs emerges from the first two of these principles. That is, we have a duty to respect their right to be free and in charge of their own lives whenever we can. They should not be treated as commodities and used as a means to our ends, whenever we have the option not to.

According to our third principle, we also have a duty to prevent other beings from experiencing unnecessary cruelty. Generally speaking we believe we owe this duty to each individual and that’s why, for example, animal welfare laws exist. While animals continue to be treated as property and used by us, we still have an ethical duty to ensure they are afforded the best possible welfare under the circumstances.

Veganism therefore seeks not only to prevent us from owning and using other animals, but also to ensure that when we do have a relationship with other animals we want to prevent them being treated cruelly.

A criticism often raised when we talk about veganism in the context of food production is the killing of pest animals in cropping. Critics say, for example, that millions of small animals like mice are killed by various practices. Even worse, trillions of insects are killed by the use of pesticides. Don’t we owe the same duty to these animals as we owe to the farmed animals? If not, isn’t it hypocrisy to worry about the farmed animals but not the wild animals that we harm?

We can examine this problem in terms of our three ethical principles. Obviously we have to produce food and we can be certain that as with everything else, we cannot avoid causing some harm to other species. But how much does food production transgress our principles and can we align food production with vegan ethics?

In the case of farming animals, we seem to be violaing all three principles. That is, farmed animals are owned and exploited, they are not free and they are harmed. Perhaps we could overlook this if we had to farm animals, but clearly we can grow plants for food instead, at least much of the time.

If we choose to grow crops for food rather than also farming animals, we seem likely to be violating just one of these principles when we cause harm and death to pest animals. How so? First, the wild animals managed as pests are free. Secondly, we have a right to protect ourselves; that is, ethically we may kill another in self-defence. Pest animals threaten our well-being by attacking our food supply and may not be reasoned with so we are within our rights to kill them. In the end, it seems we might only be guilty of causing unnecessary pain and suffering. While this is still an important problem, as consumers we may be hard-pressed to either buy foods that aren’t the result of such practices or influence how farmers treat pests.

It seems therefore that it is a lesser ethical failure to only grow crops for food than to grow crops AND to farm animals. Nonetheless, we might hope to buy plant-based foods that require minimal pest management and/or support pest control practices that minimise harm to pest species.