On the one hand, knowledge is a necessary condition, and perhaps a con­ stitutive feature, of technologies, such as communication and information technology, that contribute greatly to individual and collective well­being. Consider, for example, the Internet. So evidently technological knowledge is a good thing and ignorance of it a bad thing. On the other hand, some tech­nologies at least, e.g., nuclear technology, can be extremely harmful to indi­ viduals and collectives. Consider, for example, the atomic bombs dropped on Hiroshima and Nagasaki. So, at least with respect to some technologies, evidently knowledge is a bad thing and ignorance a good thing. Accord­ ingly, the question arises as to whether we ought to aim at ignorance, rather than knowledge, of certain technologies and, if so, which technologies.