3.3 How much do their experiences count — and what has worked?

Whether factory farming is one of the world's biggest problems depends almost entirely on one question: how much do these animals' experiences matter?

That question has two parts.

Can they suffer, and how much? This is partly a scientific question. The evidence that mammals and birds feel pain is strong. They have the relevant nervous system structures, and they respond to injury much as we do. In one well-known study, lame chickens given a choice ate more of a feed that contained a painkiller than healthy chickens did. For fish and invertebrates the evidence is thinner and more contested.

How much should their suffering count compared with ours? This is partly a question about values, and reasonable people disagree. Some researchers, including a team at Rethink Priorities, have tried to estimate how intense different animals' experiences might be compared with a human's. Their estimates come with very wide ranges.

You don't need to settle either question to see why many people take this seriously. Suppose you thought a chicken's suffering counted for only a thousandth as much as a human's. With tens of billions of animals affected each year, the total would still be large. The case collapses only if animal suffering counts for almost nothing. The EA Fellowship works through this kind of reasoning under uncertainty in Week 4.

What has worked? The clearest success is corporate campaigns. Since the mid-2010s, advocacy groups have pressed food companies to stop buying eggs from hens kept in cages. Hundreds of companies made pledges.

Treat that figure with some care. Other estimates are lower, depending on what counts as "fulfilled" and which commitments are included. Even so, campaigns like these are among the reasons animal welfare charities are judged highly cost-effective by evaluators such as Animal Charity Evaluators.

Other approaches include:

• campaigns on the welfare of chickens raised for meat, such as slower-growing breeds and more space;
• work on fish welfare;
• developing alternative proteins, from plant-based meat to cultivated meat;
• policy change.