Deduce, You Say is a 1956 Warner Bros. Looney Tunes cartoon, directed by Chuck Jones and written by Michael Maltese. The short was released on September 29, 1956, and stars Daffy Duck and Porky Pig. The title is a play on the exclamation, "The deuce, you say!"

The cartoon features Daffy Duck as the dim-witted detective Dorlock Homes (a parody of Sherlock Holmes) and Porky Pig as his sidekick Watkins (Dr. Watson), as they attempt to locate and apprehend the dangerous "Shropshire Slasher."