auxiliary verbs. may versus might

http://www.theglobeandmail.com/news/arts/russell-smith/do-you-know-the-difference-between-may-and-might/article1973684/

Russell Smith - Russell Smith | The Globe and Mail
Russell Smith: On Culture
Do you know the difference between ‘may’ and ‘might’?
Russell Smith | Columnist profile | E-mail
Globe and Mail Update
Published Wednesday, Apr. 06, 2011 4:44PM EDT
Last updated Wednesday, Apr. 06, 2011 4:53PM EDT

40 comments

Email
Tweet
Print
Decrease text size Increase text size

May is an auxiliary verb; its past is might. So you say “I may show up tonight” and your friend then reports “She said she might show up tonight.” Seems simple enough.

But it is nothing of the sort. The difference between may and might is one of the most frequent subjects of puzzlement in letters I receive from readers. Purists are annoyed that so many publications seem to use the two interchangeably, and others are confused about why it’s important. Expert sources point out a whole raft of subtleties here.
More related to this story

There's no tense like the present
A nation of language obsessives has roared
At the risk of sounding archaic, I still think that media is plural

Reader Carol Bream sent me a citation from the Ottawa Citizen that encapsulates the problem with the haziness about these verbs. This sentence ran in that paper on March 8: “The new cutting-edge concrete may have made a difference in the deadly collapse of a highway overpass in Laval in 2006 which crushed two vehicles, killing five people and seriously injuring six others who were driving on top of the overpass at the time.” The sentence is ambiguous. A reader may think momentarily that the writer doesn’t know the actual outcome of the accident. The new concrete “may have made a difference” – in other words, there was new concrete there, and we don’t know if it played any role in the tragedy? No: We do know that there was only old concrete involved; what we are wondering is whether new concrete would have made a difference. So “might” is more appropriate in that sentence.

Here is another example to make this tricky point a little less murky: “I was so distracted I might have fallen in a puddle” means “I was at risk of falling in a puddle but didn’t.” “I may have fallen in a puddle” would mean “I don’t have a clear recollection of whether I did or not.”

Here’s another example of what not to do: “He was a highly talented minor-league player, so he may have gone on to the NHL.” This suggests we don’t know if he went into the NHL or not. Using “he might have gone on” would indicate he could have gone if he had wanted to.

In short, use might when you are speculating about what could have affected a situation in the past, use may when you are uncertain of what actually happened. (“He may have thought I was insulting him.”)

Note that these sentences are all about the past. When you’re talking in the present, the differences between the verbs is much less definite. In everyday speech, the two are often interchangeable:

-----
Me - did not know that.

-------
Me - what is with the last comma?

But Mr. Beck’s bombastic, and regularly offensive, commentary had become a drag on the Fox brand.

http://www.theglobeandmail.com/news/world/konrad-yakabuski/fox-drops-a-demagogue/article1974164/