Some background:

Five "spasms" of extinctions: Rising extinction rates? (These estimates are from Norman Meyers' 1980 book, The Sinking Ark) 70 million years ago 1 per 1000 years 1600-1900 1 every 4 years 1900-1980 1 per year 1980 1 per day 2000 100 per day

"Why do species matter?"

In the Endangered Species Act of 1973, Congress declared that species are "of [a]esthetic, ecological, educational, historical, recreational, and scientific value to the Nation and its people." (Notice anything about the way those values are listed?) The Act created the present lists of threatened and endangered species, ordered federal agencies to ensure that projects they fund do not threatened listed species, and gave citizens the right to sue agencies to ensure enforcement of the Act.

Lilly-Marlene Russow, a philosopher at Purdue University, published an article with the title "Why Do Species Matter?" in the 1981 volume of Environmental Ethics (volume 3, pp. 101-12). In it, she argued for a novel conclusion. She presented eight "test cases" -- some of them real, some of them hypothetical -- for "testing" various hypotheses about what drives peoples' judgements about the importance of preserving various species (and subspecies, breeds, etc.).

Lessons from the test cases

Russow draws four immediate inferences from the intuitive judgments people typically make about the test cases:

"[O]ur concept of what a species is is not at all unambiguous; at least in part, what counts as a species is a matter of current fashions in taxonomy."

Note how the oriole and red wolf examples are parallel, but people are far more uneasy about reclassifying the red wolf and coyote as subspecies.

"[I]t is not sheer diversity or number of species that matters."

Note the lab rats example.

"[W]hatever moral weight is finally attached to the preservation of a species (or subspecies), it can be overridden."

Note the mosquito case.

(And remember smallpox, which has already been intentionally extinguished in the wild!)

Beyond that, it is unclear what makes a group of animals "special" enough to preserve. Compare these disperate cases:

Would people want to bother preserving zebras if their stripes were lost in the process?

What makes the Appaloosa, a product of intentional human breeding, so valuable to horse fanciers?

What makes the Pere David deer important?

And even if the snail darter only lived where Tellico Dam was being built, what would be so important about yet another species of darter when there are so many similar species in the genus?

Russow's aesthetic value answer to the question

Russow argues that an aesthetic value view best explains our responses to the test cases taken as a whole: If and to the extent that the individual members are beautiful preserving the speces (subspecies, breed, etc.) is important; where "beautiful" is broadly construed to include being:

awe-inspiring,

"decorative,"

of historical significance, and/or

exhibiting marvelous adaptations.

Following is a chart indicating roughly how this is so. The cell colors indicate how important the species' preservation is from the perspective in question, and I have chosen the colors and written the statements inside the cells.

Key Black on yellow background The species' preservation is of the utmost imporance! White on blue background The species' preservation is of some importance but not the utmost White on black background The species' preservation is inconsequential White on red background The species' preservation is something to be fought

(that is, its extinction would be a good thing!)