Claude translates and adapts a comment by Hagaon Rabbi Yitzchak Brand (concerning women’s wigs, but the same logic applies to other nonsense, like mechiras chametz, heter iska, grama machines and the like):
I have a method for identifying when a halachic ruling has gone wrong. Let me first illustrate it with a mathematical analogy, and then with a parable of Purim Torah.
The Mathematical Analogy
Back in school, before calculators existed, all arithmetic had to be done by hand — which meant errors were possible. But there was a way to check your work.
Say you multiply 34,567 by 67,458 and arrive at the answer 2,331,820,686. How do you know you haven’t made a mistake?
You add the digits of the first number: 3+4+5+6+7 = 25. Find the nearest multiple of 9 below that: 18. The remainder is 7.
Do the same for the second number: 6+7+4+5+8 = 30. Nearest multiple of 9: 27. Remainder: 3.
Now multiply those remainders: 7 × 3 = 21. Nearest multiple of 9: 18. Remainder: 3.
So the correct answer must have a digit-sum with a remainder of 3 when divided by 9.
Check the result: 2+3+3+1+8+2+0+6+8+6 = 39. Nearest multiple of 9: 36. Remainder: 3. ✓
If the remainder had come out differently, you’d know with certainty that there was an error somewhere — even without knowing exactly where. You’d have to go back and recheck every step.
The Purim Torah Parable
A learned Jew approached a simple man and claimed he could prove it was permitted to eat neveilah (non-kosher meat). The simple man asked how.
The scholar laid out the following chain of reasoning:
A) Slaughtering requires cutting the simanim (vital signs), but the Rov, or majority suffices — not all of them.
B) There is a rule that half (mechtzah al mechtzah) is treated as valid by mechitzos (partitions), so slaughtering only half suffices.
C) There is a rule of כל קבוע כמחצה על מחצה: “kavua” is treated like half-and-half so even slaughtering a small fraction is enough.
D) There is a rule that we do not concern ourselves with a minority, לא חיישינן למיעוטא, so even that small fraction can be disregarded, meaning no kosher slaughter is needed at all, and a neveilah is completely permitted!
The simple man replied: “I have not studied these topics — not the laws of majority simanim, not the laws of half-and-half, not kol kavua, nor the rule about ignoring minorities.
But there is one thing I do know: it is forbidden to eat neveilah!
If you have a clever argument permitting neveilah, there must be an error somewhere in your reasoning. I can’t tell you where the error is — but the conclusion is certainly wrong.”
That’s the mashal from Purim Torah.
The Application
Well, where does it say women should cover their heads? Not in the halachos of getting dressed, but in הלכות הרחקה מעריות.
Shulchan Aruch, Even Ha’ezer, Laws of Marriage, Siman 21: Introduction/Title:
“To distance oneself from forbidden relations, containing 7 paragraphs”
Paragraph 2: “Jewish women shall not go with uncovered heads in the marketplace — whether unmarried or married.”
“Unmarried” means divorced or widowed, as the commentaries explain.
Now, some authorities cite the Shiltei Gibborim as permitting the wig (sheitel). Others disagree with him, and the ruling follows the opposing view. Some say the Sh”G only permitted it in a private courtyard. Some say he was referring only to the wigs of previous generations, which were sparse as straw. Others hold the ruling follows the Sh”G, since the Rama and Magen Avraham rule accordingly, and there are even grounds to permit modern wigs — particularly since skin between the hairs is not visible.
When this is all laid out before the simple man, he says: “I don’t know who is right. I don’t know what the Shiltei Gibborim said or in what context he said it.
What I do know is that women’s wigs do not create a barrier before forbidden relations (geder erva), and perhaps one can argue the opposite is the case; they bring them ever closer.
If your argument concludes that wearing today’s wig constitutes distancing from impropriety, and that without the wig there is no such distancing but with the wig there is — that conclusion is certainly wrong. There must be an error somewhere in the argument. Go find it.”
The end.