The “Dear John” letter pictured above has been used for decades to illustrate the importance of punctuation. Running each version of it through Microsoft Word reveals no errors and no mention of the existence of the other version. While spelling is fairly straight forward to check, grammar is much more ambiguous. Depending on the context, the removal or addition of a comma can alter the entire meaning of a sentence with it still remaining grammatically correct. This letter is a clear example of that!
Errors Grammar Check Cannot Find
Dr. Daniel Kies from the College of DuPage has researched the topic extensively for ten years. By running text that contains 20 common usage errors through grammar checkers, he has documented how well they work. His findings aren’t pretty. Not only did grammar checkers catch less than half of the 20 errors, they often offered the wrong advice for correcting the error. He describes the results of his research and their importance much more eloquently than I could paraphrase it; please, please, please read it here on his web page.
One of the many grammar errors that grammar checkers cannot detect is the inappropriate use of an essential or non-essential clause. A single comma is all that differentiates the two. This and other syntactical choices that are based on semantics will always give grammar checkers problems.
Computers cannot think and therefore cannot intuit meaning from words. This limitation is why it is essential that you or someone you trust proofreads your work. Do NOT rely on your word processor to catch grammar errors for you.
More Evidence on the Issue
- Dr. Sandeep Krishnamurty from the University of Washington has created a list of examples demonstrating the futility of using Microsoft Word’s spelling and grammar checkers.
- Nick Wright has a shocking example of a paragraph that Microsoft Word thinks contains no grammar errors.
- Yu Hong Wei and Graham Davies present research assessing the effectiveness of Grammatik V, a popular style and grammar checker used by software programs.
With how easy it is for spell checking programs to make errors, it baffles me that anyone would put their trust in a program that attempts to check the correctness of grammar, a much more complex process.