Why "he would"? Why not "he will"?

[Tom]

Dear teachers

Some days ago I asked a question if will could be treated like would, and received the answer No.Please look the following discussion held between a mother and her would-be daughter- in -law. Why does she say "my son would..."?

Mother: What about your parents? Where are they?
Daughter-in-law: They are in America. I see them on thanksgiving.
Mother: It is so different--your culture from ours. My son would never think of leaving me and going away.

Tom

[Conchita]

My son would never think of leaving me and going away.

The use of 'would' in your sentence suggests a supposition:
He would never think of leaving me (...) if he had to decide someday.

Whereas 'my son will never think of leaving me' (...) is a categorical (definite) statement.

[Tom]

Thank you alot, Conchita

So considering the second part understood, we may use would?

Please see below.

Conchita-"Hello, Tom.Will you come on the
forum tomorrow?"

Tom-" Yes, I would (if I could).

So I would does not sound ugly because if I could is understood?

Please tell me in detail

Tom

[Yankee]

No, Tom!

You are changing gears in mid-conversation again. With a short form response to a "will question", ONLY will is understood (and is repeated if you give a "short form" answer).

If you decide to use would in your response, then you need to write or say more.

Amy

[Tamara]

Sorry, I didn't understand yet, can 'would' be used (without if-clause) in the context, where it sounds as a subjective opinion / private belief?

(For example, if the lady is told that someone else did some shabby act, could she just say:
My son would never do so! (referring to the fiture, but within the conditional situation) ?
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[Conchita]

[Yankee]

Hi Tamara

I agree with what Conchita has written. The "If clause" is often clearly understood and sentences are very often used that way.

Tom's example was:

[Tamara]

Amy, Conchita, thank you for the explanations.
Now I’ve got it.

Tamara
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It’s impossible to learn swimming without entering the water…