With each passing breakthrough in artificial intelligence, we're asking our machines to make increasingly complex and weighty decisions. The trouble is, AIs are starting to act beyond our levels of comprehension. In high frequency stock trading, for example, this had led to so-called flash crashes, in which algorithms make lightning-quick decisions for reasons we can't quite grasp. In an effort to bridge the growing gap between man and machine, the Pentagon is launching a new program to create machines that can explain their actions in a way we puny humans can understand.