Yesterday's New York Times again contained an op-ed piece about moral philosophy. Nicholas Kristof wrote about Peter Singer and the movement for animal rights that he more or less launched in 1973.

http://www.nytimes.com/2009/04/09/opinion/09kristof.html?em

Once again a professor is bound to find a few errors and misconceptions in a newspaper story on his specialty. It's not correct to suggest, for instance, that Bentham's important work in the 18th century was a response to Kant. Bentham had probably never heard of Kant when he wrote about the moral significance of animals' pain. And I have to imagine that Peter Singer was snickering to himself when Kristof "eagerly pushed" him to say whether he had "any compunctions about swatting a cockroach." That question is a no-brainer in more than one sense. There is indeed a question about drawing the line between the animals that are sentient and those that are not, but I have never heard of any serious thinker who believes that insects fall on the sentient side of the line.

Still, Kristof makes some important points. This is true:

What we're seeing now is an interesting moral moment: a grass-roots effort by members of one species to promote the welfare of others.

And he notes a significant recent manifestation of this effort in the US:

...the stunning passage in California, by nearly a 2-to-1 majority, of an animal rights ballot initiative that will ban factory farms from keeping calves, pregnant hogs or egg-laying hens in tiny pens or cages in which they can't stretch out or turn around.

Kristof is right to say that this is a case where the ideas of a philosopher have had a tremendous impact outside the academy. I can think of a few other instances where this has been true in the twentieth century. But I can't think of one that was based on the work of a better philosopher.