Computers are pretty dumb, but they’re dumb fast.
[On SHRDLU:] Every human sentence had to be transformed into a logical syntax that represented its meaning. The sentence “pick up a red block” was represented as the following:
(((PICK UP A BIG RED BLOCK)
(CLAUSE MAJOR TOPLEVEL IMPER ACTV PRT TRANS)
(((PICK) (VG IMPER) NIL ((PICK (VPRT VB INF TRANS MVB))))
((A BIG RED BLOCK)
(NG OBJ OBJ1 DET NS INDEF)
((A (DET NS INDEF)) (BIG (ADJ)) (RED (ADJ)) (BLOCK (NOUN NS))))))
Such programs seemed to hold promise for more generalized communication, but the secret of SHRDLU’s success lay precisely in the very narrow domain it worked within. It could understand English, but only as long as you were talking about colored blocks and the movements that could be performed on them.