A great deal of research was done (and is still being done) in discrete-reasoning AI; aside from a few successful applications (e.g., military logistics,) very

A great deal of research was done (and is still being done) in discrete-reasoning AI; aside from a few successful applications (e.g., military logistics,) very little ever came of it, at least in the direction of "general intelligence." Our intuitions about how our minds work are typically really bad, which makes it difficult to see what the needed techniques are to replicate them.