I’d like to begin with two different ideas of truth. The first appears to be the simplest: “It is true that 1+1=2.” The second is from the beginning of the Declaration of Independence: “We hold these truths to be self evident, that all men are created equal, that they are endowed by their Creator with certain unalienable Rights, that among these are Life, Liberty, and the pursuit of Happiness.” Now, these sound like quite different ideas about truth. But the process of trying to teach computers to understand truths like these—difficult for both notions—is revealing the ways in which they are similar.
The term artificial intelligence was coined in 1955 by a computer scientist named John McCarthy. Early on, McCarthy enunciated his key aim as the systematization of common sense knowledge. In 1959, he wrote: “[A] program has common sense if it automatically deduces for itself a sufficiently wide class of immediate consequences of anything it is told and what it already knows.” This has proven very difficult, primarily because it is difficult to encode, in a systematic fashion, what it means to say something is true.
