The criticism
Ethics based on sentience says: a situation is only good or bad if someone is harmed or helped by it. Some critics say: "So you think values are subjective, that they depend only on what each person feels. Then everything would be relative."
The mix-up
The author shows the criticism mixes up two meanings of the word "subjective."
The answer
Saying that value is tied to experiences (meaning 1) doesn't mean value is a matter of opinion (meaning 2).
For example, someone can argue that happiness really has value, for everyone, and that suffering is really bad, for everyone. That's an objective view about value, and at the same time it's tied to experiences.
And arguing that there are objectively good or bad things doesn't force anyone to say that species, ecosystems, or mere biological life have intrinsic value.
In short
- "Subjective" can mean "in someone's experience" or "a matter of opinion."
- The sentience standard uses the first meaning, not the second.
- You can defend objective values tied to experiences.