Now consider that this sentence you're reading is 33 words long, so the number of permutations of such sentences is hundreds of orders of magnitude larger, on the order of 10^10000.
The visible universe is estimated to contain 10^80 particles, so even if you could encode a logic gate that could recognize a word in a single particle, it seems you're still just a tad short if you're looking to hard-code intelligent responses.
True understanding consists of building a model to generate new facts as needed, amounting to an impressive compression of facts you've already seen.