What is the difference among the following questions:
Do you know where I might find them?
*Context is so important in deciding what words mean.
Without a greater context, it hard to state for sure. I think that asked in a neutral fashion, ie. no emphasis on any word, this would signal a more deferential, a softer, more polite request. With an emphasis on 'might', it could show that though someone has stated they won't be found, the speaker asks for a place that is a small to smallest possibility*
Do you know where I may find them?
*I can't envision a context where 'may', in this zero context example, denotes permission, although I'm open to being shown one, or many. I think it's the choice of words that precludes a may of permission. If the speaker had asked,
"Do you know where I may look?", referring to for example, what portions of one's property the speaker may search, then a sense of permission would be easier to see.
'may' here expresses a higher degree of possibility than 'might' and it seems that there could be previous discussion and the person feels bolder in asking, like a policeman, who knows they have a right/duty to ask.*
Do you know where I could find them?
'could' equals possibility. It differs from may and might in that it isn't a scalable possibility. It, like 'can' just asks "is it possible ...". Using 'could' over 'can' illustrates a softer, more deferential approach but the meaning of the two is the same.
Do you know where I can find them?
See discussion under 'could'.
Do you know where I would find them? // Do you know where I will find them?
- Both of these can be viewed as the speaker having some degree of certainty that the person being asked knows where the 'them' are. Using 'would', [as with the can/could distinction drawn] illustrates a softer, more deferential approach though the meaning is the same as when 'will' is used.*