Two distinct usages of "could" here?

Question

Consider this dialogue (only the third utterance is made up by me; the rest is from here):

A: "You could₁ send him an email."

B: "Yeah, I could₂ send him an email, but I won't; he only checks his email about once a week. I'll phone him."

A: "He could₃ be in a meeting right now. You want to check the schedule before you do."

In my opinion, could₁ and could₃ share the same usage of expressing factual possibility here, the first utterance representing a suggestion and the third an uncertain assumption. Besides, could₃ could be substituted for may with the meaning more or less unchanged.

As for could₂ I would think it's another story. I won't in the utterance cancels the implicature that "I" am likely to send him an email. Thus, I think could₂ is different from the other two could_1&3. The other reason for my thinking is that could₂ couldn't be substituted for may in the context because may itself isn't in a preterite form for hypothetical thinking (but might would be an alternative for the second utterance), so I believe could₂ is a purely hypothetical version of can. ( But I'm not sure whether could₂ has the same usage as in [58] The Cambridge Grammar of the English Language, aka CGEL.)

If we try to backshift the last two utterance we can see the difference:

I could₂ send him an email, but I won't. ⇒ I could₂ have sent him an email, but I didn't. #1

He could₃ be in a meeting right now. ⇒ He could₃ have been in a meeting just now. #2

I think #1 is a remote (conditional) construction while #2 is a modal perfect construction, which demonstrates in the original dialogue could₂ is different from the other two could_1&3.

Is my understanding on could₂ and could₃ correct? And is my proof method valid?

Answer 1

All of the 'could' uses here are equal meaning that 'it's a possibility'

If I substituted it for 'may' or 'might' we would then start talking about the probability of it happening, since it was affirmed that he wouldn't do the action, the use of 'may' or 'might' would be very inappropriate here.

Answer 2

One way I might look at it is like this, in which case the "could" shares the same notion again, because it is somewhat of a quotation.

A: "You could send him an email."

B: "Yeah, your suggestion is feasible, but I won't follow it."

In this case, B is just saying that the suggestion on behalf of A is a possibility, but he has decided he will not follow through on it.

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As for could₂ I would think it's another story. I won't in the utterance cancels the implicature that "I" am likely to send him an email.

I really do see what you're getting at here. Honestly, I struggle to explain it a bit, but I think the meaning of "could" remains the same. I think all three are expressing the same notion of it is possible.

A: "It is possible for you to send him an email."

B: "Yeah, it is possible for me to send him an email, but I won't; he only checks his email about once a week. I'll phone him."

A: "It is possible that he is in a meeting right now. You want to check the schedule before you do."

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Either way, I don't think it's fair to say this is a different meaning of "could". The first two sentences could also both be substituted for "be able to" (that is, "You are able to send him an email," "Yeah, I am able to send him an email, but...").

Keep in mind, "could" (or "can") and "may" are not always interchangeable.

Can I defeat Ganondorf? (questioning ability)

Could I defeat Ganondorf? (questioning possibility)

May I defeat Ganondorf? (asking permission)

As a result, I don't think it's fair to map "may" to "could" in this context. It makes the construction a bit awkward, and I think your conclusion is incorrect as a result.

Answer 3

"Yes, I could... but he never answers his emails so I'll phone him instead"

Emailing is a possibility, albeit an unlikely one.

I have the ability to email him. I have a networked computer and thus the wherewithal to email him. I am not forbidden to email him. I can email him, and I may (am free to, am not violating any rule or etiquette) email him, and were it not for the fact that the $*%&%! luddite never answers his emails, I might have emailed him! But I opt not to do so. I'll phone him instead.

So perhaps @Kinzie B, the OP, is looking for the nuance of option here? Choice is a particular kind of future possibility. could-1 and could-2 both have to do with choice.