There’s a new way to edit DNA. It’s called CRISPR, and it’s taking science by storm. Its versatility and speed have led scientists to explore all sorts of uses for it. One of the most radical ideas--proposed today in a pair of papers–is to use it to alter the DNA of species we want to get rid of. Think of malaria-bearing mosquitoes, bat-killing fungi, and the like. It’s a provocative idea, but does it threaten to do more harm than good? I take a look at the issue in my new “Matter” column for the New York Times. Check it out.