The opposing teams are preemptively declaring victory.
"Our reasoning is such that our position is the only logical one. You guys may as well not even bother with your weak and ineffectual arguments."
Close-minded was first, but closed-minded is dominant:
Here's the earliest close-minded reference I can find from a Narrative of a Journey in the Interior of China, by Clarke Abel, 1818:
I found closed minded back to 1913 in The Century Magazine:
Edit:
After considering @FumbleFingers' comments here and his subsequent answer, I have to agree that most of the earlier close-minded references found through Google Books (including the one above) are using close |kloʊs| in this sense (from NOAD):
• not willing to give away money or information; secretive : you're very close about your work, aren't you?
This is also proven by this definition of uncommunicative from John Craig's A New Universal Etymological Technological, and Pronouncing Dictionary of the English Language, 1859:
It seems the phrase was once a common description for someone who "kept their own counsel"—usually used as a derogative, but sometimes as a compliment.
However, I did find this earlier use of close-minded specifically to mean the opposite of open-minded from an 1898 issue of The Outlook:
I also found evidence of a shift towards this sense of close-minded in other writings by the early 1900s. So, to conclude, I think the only thing new about the confusion evident by the 1960s was the frequency of the two terms in print.
I realize this may not ultimately answer the question, which is correct, but the timeline seems significant to me.
Best Answer
Grammatically, the correct answer is "interesting topics". See the bottom of this answer though for a suggestion for improvement.
Many learners of English as a second language have problems getting the distinction between ing and ed adjectives right. But the basic rule is actually very simple. "Interested", "bored", "frightened", and all the other -ed adjectives describe an emotion. "Interesting", "boring", "frightening", and all the other -ing adjectives describe the cause of an emotion.
Thus, "these topics are interesting" => "interesting topics"
"I am interested in these topics" => "topics I am interested in"
Here "interested" is an adjective formed from the past participle, so it does not describe the past.
However, if your question was about how to phrase this, a better way would be to ditch the word "topics" and just use "interests":