The first and most important precept is the precept to refrain from destroying living creatures:
“Panatipata veramani sikkhapadam samadiyami.”
It’s the Buddhist version of the biblical Sixth Commandment (“Thou Shalt Not Murder”) and roughly parallels the Hindu/Jain doctrine of ahimsa (non-harming).
At first blush, it seems the easiest precept to follow. Far easier, say, than never telling an untruth or maintaining complete sobriety.
The more one examines the precept, however, the more problematic it becomes.
What does it mean to refrain from destroying living creatures?
In India, the Jains sweep the ground in front of them so as not to inadvertently kill any insects. Does the Buddha ask us to do the same?
As it turns out, no. If we accidentally trample an insect, no bad karma is created. This is because there was no intention to kill. In addition (in some traditions) insects are thought to be lower on the sentience scale than large mammals, primates, cetaceans, etc., and killing them has less karmic import.
Intention is the key to karma. Accidents, in general, do not create bad karma the way intentional acts do.
On the other hand, some accidents are almost predictable. What if one goes about carelessly and heedlessly and accidentally kills another being? A drunk driver doesn’t intend harm, but driving while intoxicated raises the odds that harm might occur. Here in the West we consider that to be vehicular homicide. Does this kind of unintentional but heedless killing create bad karma according to Buddhist doctrine?
What about the killing of animals for food?
The Buddha did not prescribe vegetarianism. Buddhist monks are permitted to eat meat, for example, if it is put in their alms bowl by a lay supporter. They are not permitted, however, to eat an animal that has been killed on their behalf.
As lay Westerners we have an endless variety of protein sources available to us that are not the result of killing animals: dairy products, unfertilized eggs, soy-based products, legumes, etc. Should we refrain from eating killed animals?
Meat sold in supermarkets has not been killed specifically for our benefit. There was no particular consumer in mind at the slaughterhouse at the moment the animal was killed. Is it therefore all right to buy meat in the supermarket? Or is that disingenuous? After all, if more people declined to buy meat, the law of supply and demand would result in a decrease in animal killing.
In addition to concerns about killing per se, there are also serious ethical concerns about the way animals are raised on modern factory farms. Who is creating a greater moral offense: the hunter of wild game, or the agribusiness livestock breeder who is raising animals under unnatural circumstances?
Buddhist traditions vary in allowing or discouraging meat eating. Some Buddhist traditions permit meat eating (e.g., fish in Thailand, yak meat in Tibet) and others discourage it.
And what of harmful pests: bed bugs, fleas, flies, mosquitoes, cockroaches, fire ants, and rodents? Is one permitted to rid one’s home and neighborhood of them, or must one endure them, even when they are unsanitary or serve as a vector for serious infectious disease?
And what about bacteria and internal parasites? Is one permitted to use antibiotics?
And what about the autoimmune system? Doesn’t the autoimmune system kill foreign living organisms all the time?
And what about killing in self-defense or to protect one’s family, neighbors or countrymen?
To complicate matters further, Mahayana Buddhism introduces the concept of “skillful means” (upaya kausalya). Under certain circumstances one may violate precepts when one’s motivation is wholesome.
Tibetans, for example, venerate Pelgyi Dorje who assassinated King Langdarma almost 1,200 years ago. Langdarma allegedly suppressed Buddhism and persecuted Buddhist monks, and Pelgyi Dorje killed him to preserve the Dharma for the benefit of all beings and to save Langdarma from creating even worse karma for himself.
Similarly, in the Upaya-Kausalya Sutra, a virtuous sea captain named Great Compassion (the Buddha in a previous lifetime) is permitted to kill an assassin who plans on killing a cohort of 500 bodhisattvas who are aboard ship. In doing so, Great Compassion is willing to be reborn in a Hell Realm as a consequence, but his act is morally commendable, and his karma is not as bad as it would have been had his motivation been impure.
I am raising a series of questions and resolving none.
It’s not my intention to cite this-or-that text in this-or-that tradition to support one answer or another. I refer the interested reader to Peter Harvey’s excellent book  on the topic if they’re interested in exploring Buddhist ethical doctrine in greater depth.
Instead, I only wish to point out that things are not as easy or straightforward as they might initially seem. When we vow to refrain from killing living beings, we are being invited into an exploration of how far we are willing to go to put the vow into practice. Are we willing to allow ourselves to be killed by a tiger, as the Buddha did in a previous life in one of the Jataka Tales, so that her hungry cubs might live? Are we willing to kill an intruder who is invading our home and threatening our family? If we lovingly rescue spiders by carefully removing them from our homes, are we as loving with an infestation of cockroaches? Are we willing to eat fish, but not beef? Will we join pacifist protests when our country goes to war? Where will be draw the line in our lives?
There is a famous Quaker anecdote about William Penn. When Penn first became a Quaker, he still wore his ceremonial dress sword on formal occasions, as was the custom of the time. He was aware, however, of the moral conflict between Quaker pacifist beliefs and sword-wearing, and asked George Fox for advice. Fox replied “I advise thee to wear it as long as thou canst.” When they met again a short time later, Penn no longer had his sword. When Fox asked where it was, Penn replied “I have taken thy advice; I wore it as long as I could.”
This is what Buddhism asks us to do. To investigate the circumstances of our lives. To live with difficult questions and address them as best we can in the moment. To see how far we can go to refrain from killing in our lives, knowing that the extent to which we are willing to go may change and evolve as we proceed along the path.
Rather than being absolutes, Buddhist training precepts are invitations to explore how our lives change as we take on certain ethical challenges.
As the Buddhist saying goes, “Ehipassiko:” Come see for yourself.
-  Harvey, P. (2000). An Introduction to Buddhist Ethics. Cambridge: Cambridge University Press. ↩