I already checked the dictionary, but I am still confused about "personal":
- This is just my personal opinion.
- This is just my opinion.
What would deleting "personal" do to sentence 1?
Please see “My personal opinion is…” Is it always pointless to use the words “personal” and “personally”? on English Language & Usage.
From @JoeZ's answer:
A person can have multiple opinions on a matter. For example, a climate scientist's professional opinion on whether global warning is an anthropogenic phenomenon would probably be that the evidence points towards it being so, while personally they may think it's just the perpetuation of natural climate cycles.
From @andy256's answer:
Personal can be used…
To distinguish a personal opinion from another opinion, for example a professional opinion, given by a professional person. It's my personal opinion....
As emphasis that the opinion is mine, and may differ from others. Personally, I would advise you...
I don't think there is a significant difference in meaning of these two sentences. I agree that when we say this is my personal opinion, it means that it is my own opinion, not influenced by any other person(s). But, it is also a fact that when we say this is just my opinion, it signifies pretty near the same thing because the adverb "just" (meaning only, exactly or completely is there to emphasize that the opinion is mine, not anybody else's. However, the former sentence, especially with the use of just, is more emphatic than the latter one.