We all know the value of a good dictionary. For a child or a young adult making their way in a world of antiquated literature and the diseased mutterings of the overly erudite, a dictionary is a good friend, a fine companion and an essential aide in gaining the vocabulary of adulthood.
Where it fails is in any other usage. Now, don't get me wrong - a good dictionary can probably stop a small bullet in a pinch, or be used for starting a fire.
But when you're looking to define your position in an argument a dictionary is a liability.
You see, dictionaries aren't written by the spectral god of the English language, or put together by a magical team of accuracy pixies in a mystical fairyland of unconvincingly rhythmic hammers and toys.