What it means to have interests
In this sense, saying we should consider sentient beings "because they have interests" is the same as saying they can be harmed or helped.
The idea being debated
Some writers say species have interests too, because they:
- carry out complex activities that would be more than the sum of what their members do;
- have a past, a present, and a "direction toward the future";
- have their own unity and identity;
- would have a stronger interest in continuing to exist than their members, because they don't have to die.
This could be used to justify killing animals to preserve species.
The answers
- A species' complex activities can be explained by what its members do, without assuming anything extra.
- Having a past, a present, unity, and identity isn't enough to have interests. Political parties and cities have all of that too, and nobody thinks a city can suffer.
- To really have interests, things have to be able to be good or bad for you. And that requires feeling. A species doesn't feel anything.
The word "interest" is misleading
Sometimes we say "it's in the species' interest" as a figure of speech, just as we say "the car needs oil." The car doesn't suffer without oil; it just stops working.
In short
- Having interests means being able to be helped or harmed.
- The arguments that species have interests would apply to cities too.
- Only beings who feel really have interests.