Kenneth G. Wilson (1923–). The Columbia Guide to Standard American English. 1993.
may, might (auxs.)
For events in the present or immediate future, use either may or might (I may [might] decide to go after all), but for past time, most Standard users still prefer only might, as in, "Yesterday I might have decided to stay home", not the increasingly encountered, "Yesterday I may have decided to stay home."
This seems an idiotic example. I'm having trouble trying to imagine a person who can't remember whether they decided to stay home or not.
Regardless, it isn't even an argument for might as a past tense of can. It's that same confused argument that Professor Brians made and he was just repeating someone else's nonsense.
Journalese is now peppered with "may" where until recently "might" has been solidly entrenched.
Yeah right.
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Also:
might
modal verb ( 3rd sing. present might )
past of may , used esp.:
• in reported speech, expressing possibility or permission : He said he might be late.
Reported Speech IS NOT AN INDICATION OF PAST TENSE. It merely marks the speech as indirect reported speech. It indicates that the speech is not a direct quote.
• expressing a possibility based on a condition not fulfilled : We might have won if we'd played better.
Debunked in the posting about brian's errors.
• expressing annoyance about something that someone has not done : You might have told me!
Are you suggesting that this is an example of 'might' as the past tense of 'may', David? Since we can substitute 'could', would it also qualify as the past tense of 'may'.
• expressing purpose : He avoided social engagements so that he might work.