If you import a lulav or esrog from Australia, do you have to hold it upside-down?
This was a halachic question that was seriously discussed back in the nineteenth century (see the discussion at this link). There is a halachic requirement that the arba minim be held derech gedelason, "in the way that they grow," which is why we must hold them pointing upwards. What, then, do we do with arba minim that come from countries on the other side of the world? Perhaps they should be held upside-down?
No less an authority than Rav Yaakov Ettlinger, famed author of Aruch LaNer and a university graduate, discussed this question. He suggested that it was more reasonable that they should be held in the normal position. Others, however, apparently disagreed.
To the modern reader, this sounds ludicrous. Australians are not "upside-down"! There is no absolute frame of reference!
This case exemplifies the challenge that I have faced many times in teaching the rationalist approach to Chazal. Very few people are able to appreciate that errors made by people in very different eras and cultures do not reflect any sort of stupidity. Most people think that if someone is alleged to have believed something that we today consider "obviously" wrong, then that person is being alleged to have been foolish. This can have two types of harmful consequences. Some will simply refuse to believe that people could have made such errors - and thus err. Others will accept that such errors were made, and will look down on those who made them - which is unjustified.
I always try to give examples of how intelligent people today can be wrong about things without it reflecting badly upon them. For example, I show people that they would believe certain incorrect things about animals, for the best of reasons. But in this particular case of the upside-down lulav, I can think of a better way to make my point. Take a look at the following map of the world (you can click on it to make it fill the window):
Most people will have part of their brain screaming that it's wrong, even though another part of their brain acknowledges that there's nothing objectively wrong with it. "North" is not "up"! Yet, despite the fact that we've been educated since children to know this, and we've seen pictures of the earth from space, it's still hard to come to terms with it sometimes. All the more so in times past would it have been challenging for people to internalize the idea that north is not up.
In earlier times, it was not foolish to believe that insects spontaneously generate, that the heavens are a solid dome, that the heart is the seat of the mind, or that God is corporeal. There is no reason whatsoever to look down on people who possessed such beliefs. If we can internalize that idea, then we can be more objective in our analysis of which such beliefs were actually held, and by whom.
(Hat-tip: Yaakov Yehuda)