arch attitude

I think I’ve been quite cordial! What is an “arch attitude”?

and made unsubstantiated claims, with no offering of alternatives

Just let me know what claim you need substantiation of and/or alternative to and I’m happy to oblige if I can! Ask and ye shall receive!

You haven't given me a single reason to stop and listen, much less ask questions.

Nor do I intend to! If you want to know, you’ll ask (and/or earnestly and considerately read what I write; “listen” as you said) ! If you are happy to continue not knowing - you won’t. Simple! I can’t force you to learn about other perspectives and I wouldn’t even if I could!

they simply cannot identify a crucial fact that supports their position

Firstly, there really aren’t any flat earthers outside of the psyop and the useful idiots that fall for it. In any case, I’m a flat earth researcher - we study the psyop and related topics.

Secondly, what is a “crucial fact”? Can you provide an example?

like the observation of the "largely spherical" Earth from outer space

If it were YOUR observation it might be worth discussing, but personally I am more of a science lover. In science we don’t simply observe and declare, we measure and experiment! And as independent researchers/students we should never rely on unvalidated and unvalidateable claims for evidence (aka abject appeal to authority). There are very good reasons for keeping our discussion “down to earth” - the chief one being that the world, who’s shape we are discussing, is down here!

I am not interested in discourse with dishonest people.

Me neither! However, I have given you no reason to suspect dishonesty (and if I have, please cite a specific lie/falshood so I can meaningfully respond). I work very hard to be earnest and honest, and effective communication is very difficult and takes significant effort from all participants! Try not to rush to judgement if you can!