From Grammarly:
It happens all the time—you and someone you know disagree about something more important than who has the best curry in town, and you need to hash it out. Whether it’s a peer, your boss, your landlord, or your kid’s teacher, you want to err on the side of delicacy and professionalism.
So how do you do that in a way that’s respectful—and ultimately productive? You want to make your perspective clear, confident, and compelling without anyone feeling attacked or at cross purposes. Below, we’ll suggest a few handy phrases and strategies to help you disagree respectfully.
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Is this the place?
Occasionally, the best way to respectfully disagree isn’t in writing at all. A live conversation may be a better way to ask and answer questions, exchange thoughts, and build consensus. Consider this before getting carried away with a long draft enumerating your righteous points.
It may even turn out what seemed like a disagreement was more of a misunderstanding. Phew.
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Keep it tight; empathize
Suppose your landlord emails to say while they’d hoped to upgrade your kitchen windows next month, it’s now looking more likely the month after. You could detail your displeasure in a three-page tirade, but that sounds exhausting and may make you seem irrational. One or two sentences should suffice:
“Thanks for the update, Daryl. That’s later than we’d hoped, and I don’t imagine having this process drag on is any fun for you, either.”
Note how that last part acknowledges Daryl has feelings and a point of view in this, too. This shows respect and is key to resolving your disagreement—as is this next item.
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Ask questions; empathize some more
Questions can politely point to what you want without seeming unduly demanding or unkind. Picking up where we left off with your landlord above, you might next ask this:
“Is there any way to expedite the installation? If not, could we negotiate a reduction to our rent or our portion of the heating bill in the meantime, since our kitchen is so drafty?”
Questions also keep the conversation moving forward and show you value the other person’s input. And if you’re worried the many questions you’re asking will become annoying, a concise way to acknowledge as much is, “Not to belabor this, but…” (That said, do try to read the vibe and avoid belaboring anything you don’t have to.)
Link to the rest at at Grammarly
PG completely endorses the approaches Grammarly recommends.
Unless you suspect a dispute may be coming down the road.
PG isn’t talking about a polite disagreement about when the new stove will be installed, but rather what happens if the new stove is never installed or if it’s installed by an idiot and starts a fire.
In other words, if some sort of a legal dispute is foreseeable.
If there’s a fight that ends up in Small Claims Court or if each side lawyers-up, a statement made for the purpose of smoothing ruffled feathers might be subject to a different interpretation.
In social situations, when discussing a past event with friends, PG might be inclined to say something like, “I might be wrong, but I remember that Chipper had too much to drink and took the first swing, but perhaps I’m confused about what happened.”
If PG were later asked about Chipper, his state of mind and what he did in some sort of formal setting, perhaps with a judge nearby, if he said something like, “Chipper was drunk and tried to punch Buzz in the nose,” Chipper’s counsel might ask if PG had admitted he might be confused or wrong on a prior occasion.