Circulating around the internet in various forms is a short text, often in poster form, to the effect: “‘Let’s eat Grandma!’ ‘Let’s eat, Grandma!’ Commas save lives.”
I’m not convinced that commas save lives or, if they do, that this pair of sentences is a very good example of it. Firstly, I doubt that anyone in the history of the world has ever written either of those two sentences in earnest. Regarding the first sentence, if you were seriously considering eating Grandma, you wouldn’t want to leave written evidence of it; regarding the second, you would just say it, rather than spending the extra time writing it, unless, perhaps, Grandma was deaf, in which case miming would still be quicker than writing. Secondly, I doubt that anyone in the history of the world has ever said the first sentence in earnest. If you were seriously considering eating Grandma, you would probably raise the suggestion in a far more roundabout way. Thirdly, no-one would say the first sentence in exactly the same context as the second: the second sentence is directed to Grandma; the first is directed to anyone else (probably not in Grandma’s presence, but possibly with her there, especially if she if deaf). Fourthly, the grammatical structure and/or meaning of a spoken sentence are indicated (and can be changed) by intonation and timing. ‘Let’s eat / || Grandma’ (that is, upward intonation, slight pause) is unambiguous when spoken.
So, commas might indeed save lives, but only when two sentences are approximately equally likely to be formulated in the first place, and approximately equally likely to be written in the second. More plausible is the story:
Alexander III personally wrote the death sentence of a prisoner with the following words: “Pardon impossible, to be sent to Siberia.” His wife Dagmar (daughter of Christian IX, king of Denmark) believed the man innocent. She saved his life by transposing the comma. The sentence then read: “Pardon, impossible to be sent to Siberia.”
Snopes categorises this as a ‘legend’. The potential ambiguity would be eliminated by writing complete sentences ‘It is impossible to pardon him – send him to Siberia’ or ‘Pardon him – it is impossible to send him to Siberia’, or possibly eliminated by writing in Russian or French, which may or may not have the same structures.
Less plausible is:
An English professor wrote the words, “Woman without her man is nothing” on the blackboard and directed his students to punctuate it correctly.
The men wrote: “Woman, without her man, is nothing.”
The women wrote: “Woman: Without her, man is nothing.”
And then there’s the implausibly ambiguous:
I want a man who knows what love is all about you are generous kind and thoughtful people who are not like you admit to being useless and inferior you have ruined me for other men I yearn for you I have no feelings whatsoever when we’re apart I can forever be happy will you let me be yours Alex