The objection
Someone could say: "I agree with equal consideration. But humans are smarter and so they suffer more. So putting humans first would just be following the size of the suffering."
Sometimes it's true
The author admits that in some cases, being able to think more makes someone suffer more. For example, a person can suffer from worrying about something bad that's going to happen in the future, and an animal maybe can't.
But sometimes it's the opposite
In other cases, understanding less makes you suffer more:
- an adult getting a shot knows the pain will pass; an animal or a baby doesn't know that, and may feel pure terror;
- someone who understands the situation can be calmed down with explanations; someone who doesn't, can't.
Also, having fewer abilities usually goes along with more vulnerability: less chance to defend yourself, run away, or ask for help.
Conclusion
More intelligence doesn't always mean more suffering. Sometimes it does, sometimes it means the opposite. So you can't use species as a shortcut to say who suffers more. You have to look at each situation.
In short
- Sometimes, understanding more makes you suffer more.
- Often, understanding less makes you suffer more, from fear and vulnerability.
- So you can't put humans first just by assuming they suffer more.