Pride is one of the seven deadly sins. You might take interest in viewing these two threads, pride is briefly talked about...
Seven deadly sins~Squatter of Amon Rhun
7 Deadly sins vs. 7 Heavenly virtues~Boromir88
The way I view it is there is pride and arrogance. I think one can have a certain amount of pride in them, it's a good trait to have. Then there's arrogance when you are just so full of yourselves. Of course many people associate Boromir with this trait. I think he is more "proud" then the other members, and in the end it very well could cost him.
However, a lot of people think just because he brags about Minas Tirith, means he's arrogant, talking as if Minas Tirith is the best. I don't view that as any different then me saying the US is the best place to live, it's just patriotic. Surely people from Germany, France, Czech Republic...etc will disagree, but it's a matter of patriotism.
It is said that patriotism was a reason for WW1. Everyone was so proud in their nation as being the best, being better then everyone else, they got into this arms race competition. So, I can see how Tolkien would look down on pride, since it is said to be one of the causes of WW1. For the time he was living in, I think it was common for people to look down on pride.
I hope that made sense
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