Is trial-and-error needed to solve Sudoku puzzles ...

... or are you just dumb?

The truth is, most of the time, the latter is true. The vast majority of Sudoku puzzles can be solved by logic, and logic only. When someone claims that a certain Sudoku puzzle cannot be solved unless trial-and-error is used, you can almost be certain that he/she has not tried hard enough (or he/she is just plain dumb).

But there are indeed a small number of existing Soduku puzzles which do require trial-and-error. Read Michael Mepham's Farewell to Ariadne's thread?.

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"Ariadne's thread" comes from a Greek mythology in which Ariadne gives a thread to her lover to help him find his way out of a labyrinth.

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I only write about Sudoku as a phenomenon. Personally I don't like this game since I hate spending so much time and enduring so much frustration trying to solve the puzzle. I am just too dumb to play this game of logic.