The emergence of CRISPR, a powerful tool for gene editing, promises to correct devastating genetic diseases, but it also raises concerns about how it will be used and who will make those decisions. Neal Baer, in his new book “The Promise and Peril of CRISPR,” brings together a series of essays by bioethicists, geneticists, and others who explore ethical and policy considerations raised by the technology. We spoke to Baer, co-director of the master’s degree program in Media, Medicine, and Health at Harvard Medical School; about whether there are unique questions raised by CRISPR as a dual-use technology, the book’s recasting of the case of Chinese scientist He Jiankui, and why he thinks there needs to be public debate now over the use of the technology to make heritable changes to the genome.