a) well, it isn't a syllogism, but yes, it's usually bollocks b) it's not wholly true, it's impossible to tell in what sense it's true, and it's very rarely relevant to whatever people are trying to prove from it, so... c) both, and... d) it's just really cocking annoying, it's a big fat cliché, people act as if it was as a total argument-annihilator ("Ah yes but for a long time people believed the earth was flat, ergo I WIN I WIN I WIN!") and consequently it's usually delivered with an air of punchworthy smugness.
Basically, it usually seems to be used to mean "people were wrong about X, therefore they are equally likely to be wrong about Y" which is simply nonsense when used without any kind of qualification.
ALSO, it is often used as a proxy for "the vast majority are so stupid they'll believe any old shit", which i) is fairly unpleasant, and ii) is usually irrelevant, as iii) this "majority" usually just means "people the speaker disagrees with" or even in extreme cases "people who are not the speaker".
Also, most of the things for which Joe Blogs (he does, too, usually) uses the flat-earth comparison tend to be things for which Joe Blogs and the internets at large have far, far more evidence than flat-earth believers had for the flatness or otherwise of the earth. "We just don't know but we believe X" is one thing when you're trying to pick mud out of your teeth inbetween fighting off marauding beasts and your only real source of information is looking at what you can see with your two eyes; it's quite another thing when somebody is presenting you with strong scientific evidence for or against X and you're sticking your fingers in your ears saying "la la la FLAT EARTH FLAT EARTH".
no subject
b) it's not wholly true, it's impossible to tell in what sense it's true, and it's very rarely relevant to whatever people are trying to prove from it, so...
c) both, and...
d) it's just really cocking annoying, it's a big fat cliché, people act as if it was as a total argument-annihilator ("Ah yes but for a long time people believed the earth was flat, ergo I WIN I WIN I WIN!") and consequently it's usually delivered with an air of punchworthy smugness.
Basically, it usually seems to be used to mean "people were wrong about X, therefore they are equally likely to be wrong about Y" which is simply nonsense when used without any kind of qualification.
ALSO, it is often used as a proxy for "the vast majority are so stupid they'll believe any old shit", which i) is fairly unpleasant, and ii) is usually irrelevant, as iii) this "majority" usually just means "people the speaker disagrees with" or even in extreme cases "people who are not the speaker".
Also, most of the things for which Joe Blogs (he does, too, usually) uses the flat-earth comparison tend to be things for which Joe Blogs and the internets at large have far, far more evidence than flat-earth believers had for the flatness or otherwise of the earth. "We just don't know but we believe X" is one thing when you're trying to pick mud out of your teeth inbetween fighting off marauding beasts and your only real source of information is looking at what you can see with your two eyes; it's quite another thing when somebody is presenting you with strong scientific evidence for or against X and you're sticking your fingers in your ears saying "la la la FLAT EARTH FLAT EARTH".