In How to Count Animals, more or less, Shelly Kagan sketches and argues for a hierarchical account of moral status. Although the book is fairly lengthy at 304 pages of text, Kagan is correct in calling it a sketch, since what this book provides us with is a foray into one aspect that a comprehensive ethical theory must include, in his view, if it is to be plausible. Even so, the work that he does, if one accepts hierarchy, opens up many different avenues to be further pursued in animal ethics.
Elmore, Benjamin A.
"Review of How to Count Animals, more or less,"
Between the Species:
1, Article 8.
Available at: https://digitalcommons.calpoly.edu/bts/vol25/iss1/8