These verbs have distinct uses that most native speakers of English instinctively understand. Idiomatically speaking, you “say” that something is so, or you “tell” someone that something is so. “Tell,” in other words, needs a personal direct object. You don’t “tell” that something is so — e.g.:
o “After reviewing emergency procedures, he told [read ‘said’] that he would let me fly it.” Gibson Armstrong, “He Hitches Ride in Wild Blue Yonder,” Lancaster New Era, 5 Jan. 1997, at B8.
o “He told [read ‘said’] that he trained until he was nauseous and pulled his muscles.” Patricia de Martelaere & Kendall Dunkelberg, “Scars,” Literary Rev., 22 Mar. 1997, at 527.
o “Mention the LSU fan he dumped into a garbage can and Knight will tell [read ‘say’] that if he had have [read ‘if he had’] been out of control, he’d have decked the guy.” Mike Littwin, “Self-Tarnished Knight Needs Same Tough Love,” Rocky Mountain News (Denver), 15 May 2000, at C2.
Still, it’s permissible to say “tell that to your father” and the like — e.g.: “OK, RWD is better for towing, but tell that to the owner of a 4-cylinder engine.” Jim Mateja, “Sienna Makes Up for Rare Toyota Miscue,” Chicago Trib., 21 Sept. 1997, at 1. In this usage, “tell that to” is a set phrase.
Language-Change Index — “tell” misused for “say”: Stage 1.
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Quotation of the Day: “Good usage is not something to be evolved from one’s own consciousness, or to be deduced by some process of reasoning; it is something to be ascertained. It must be learned just as language itself is learned.” Thomas R. Lounsbury, The Standard of Usage in English 98 (1908).
