Our electronic devices—or at least many of the processes that occur within them—are literally parts of our minds. And our consideration of Apple’s and the FBI’s arguments ought to flow from that fact.

This may sound ridiculous. But in an important co-authored essay and then in a book, the philosopher Andy Clark argued for something called the extended mind hypothesis. The basic idea was that we have no reason to treat the brain alone as the only place where mental processes can occur.