McMahan published "The Meat Eaters", an op-ed for the New York Times on predation as a moral issue, in which he argued that preventing the massive amounts of suffering and death caused by predation would be a good thing and that the extinction of carnivorous species could be instrumentally good if this could be achieved without inflicting "ecological upheaval involving more harm than would be prevented by the end of predation". McMahan received a number of objections to his arguments and responded to these in another op-ed published in the same year, "Predators: A Response". He later published his arguments as a chapter titled "The Moral Problem of Predation", in the 2015 book Philosophy Comes to Dinner. Peter Vallentyne argues that it is permissible for humans to intervene to help prey in limited ways, if the cost to humans is minimal, but that we should not eliminate predators. In the same way that we aid humans in need, when the cost to humans is minimal, humans might help wild animals in limited circumstances. Martha Nussbaum asserts that the predation problem and what should be done to solve it should be the subject of serious discussion, also arguing that there should be research into future solutions. Nussbaum draws attention to a need to convince people that predation is a problem and to challenge the common conception of predation as exciting and enthralling, which she believes has a negative impact on human culture. She goes on to challenge the idea of animals, who are preyed upon, as existing to be food for other animals, rather than being made to live for their own lives. Nussbaum concludes that humans, who have extensive control over animal lives and habitats, need to face up to their responsibilities towards wild animals and work towards their flourishing, rather than harming them. Some ethicists have made concrete proposals for reducing or preventing predation, including stopping the reintroduction of predators in locations where they have previously gone extinct, and removing predators from wild areas. Environmental ethics In 1984, the British ecologist Felicity A. Huntingford published "Some ethical issues raised by studies of predation and aggression", in which she discusses ethical issues and implications regarding the staging of artificial encounters for studies of predator-prey interactions. In the context of ecology, predation is considered to play a crucial and necessary role in ecosystems. This has led some writers, such as Michael