I. Sometimes, only telling a lie will prevent the triumph of falsehood-לטעון שקר להוציא דין לאמיתו. Would such a thing be muttar?
b. Maybe not.
I hope that was helpful.
Thank you to my Yetzer Hara, who helps me to do my best thinking in learning during davening. I owe this much-improved version to his assistance.
When the Torah prohibits something, there are usually exceptions to the prohibition, circumstances under which some good outweighs the bad, or where some need is greater than the prohibition. We have rules of עשה דוחה לא תעשה,פקוח נפש, and עבירה לשמה, such as the case of Ya'el. On the other hand, some issurim are (almost, but not quite,) absolutely forbidden, such as Avoda Zarah, Gilui Arayos, and Shfichas Damim. Similarly, there is a rule of אסור להציל עצמו בממון חבירו, that it is "prohibited" to save oneself by stealing from another person, which a very few Rishonim seem to understand to mean actual prohibition. (The vast majority of Rishonim understand it to mean that if a man steals to save a life he remains liable to repay what he took.)
In light of the above, it's interesting to see some baalei machshava writing that "In Judaism, the ends do not justify the means." For example, you have the Sfas Emes in Shoftim quoting R' SB of Pshsch to the effect that צדק צדק תרדוף teaches us that להיות רדיפת הצדק בצדק לא בשקר, that only kosher means should be used in pursuit of important goals. This is often quoted, e.g., here, where he says שהמטרה לא תכשיר את האמצעים, אף שהמטרה הוא צדק הרדיפה לצדק היינו האמצעים להמטרה, צריכה ג״כ להיות עם צדק . As we have seen, the Torah certainly does tell us that the ends justify the means, with very few exceptions. Of course, the quoted thought was not referring to cases of Dechiya- of extreme necessity, or superior value. But one must realize that we certainly do weigh costs and benefits in the Torah, even regarding serious issurim- within the parameters of Dechiya. Once the concept is validated in the case of Issurim, the application regarding other values is certainly situational. Their words should be taken more as a mussar derhehr, a reminder that we have to carefully weigh the public and personal costs when, under the burden of the needs of the klal, we might be tempted to bend our principles le'sheim shamayim.
As human beings, Faith in the Ribono shel Olam is our paramount goal. But when it comes to emulating the Ribono shel Olam, Truth is the fundamental value. The Seal of the Ribono shel Olam is Emess- דאמר רבי חנינא חותמו של הקב"ה אמת (Shabbos 55a.) The Torah, which begins and ends with Emess, repeatedly and explicitly prohibits falsehood. We are told מדבר שקר תרחק and אבן שלמה וצדק יהיה לך and ולא תכחשו ולא תשקרו איש בעמיתו.
There is a lower level of "relatively minor" falsehood, regarding personal matters that have no bearing on others, regarding which the Gemara (BK 24b) says one may prevaricate in the interest of humility, modesty, and gratitude to a host. Let us call this category "Immaterial falsehoods." Perhaps the passuk in Mishlei (12:22) תועבת ה' שפתי שקר, or even Chazal's words (Sotah 42b) ....ארבע כתות אינן מקבלות פני השכינה... כת שקרנים would apply to him. But I think that's only for a person for whom truth loses its value, a person that makes a habit of lying, such that the passuk in Yirmiah (9:4) למדו לשונם דבר שקר העוה נלאו would apply to him. I don't think the passuk of מדבר שקר תרחק or אבן שלמה וצדק יהיה לך would apply there. (This is discussed at length in רי"פ פערלא ספר המצוות לרס"ג ח"א מ"ע כ"ב) Here, we are talking about "Material falsehoods:" matters where there is an expectation of truth and serious consequences- where your words directly affect another. According to those shittos that the issur de'oraysa only applies in the presence of Beis Din (Rav Perlow's hachra'a in the רס"ג,) then this discussion will refer to falsehoods in the presence of Beis Din.
The question is as follows. We know that a false oath is an absolute issur; the circumstances are irrelevant. Even if the false oath is taken to prevent a cheater and a liar from robbing you, it is absolutely forbidden to swear falsely. It is like any issur in the Torah, and to avoid an issur one must spend or lose all his money, as the Rama says (YD 157:1- ואם יוכל להציל עצמו בכל אשר לו צריך ליתן הכל ולא יעבור לא תעשה. [ר"ן פרק לולב הגזול ורשב"א וראב"ד וריב"ש]) Are the general laws of honesty and truthfulness and rectitude in weights and measures like taking an oath? Or are they concept-commandments to create a world of truth and honesty, to bring about a just result?
If the law of honesty is like other issurim in the Torah, even though one would be allowed to transgress the law where the rules of Dechiya applied, there is no Dechiya to save yourself from being cheated or to prevent someone else from winning through falsehood. If, on the other hand, the laws of honesty are intended to generate justice and fairness, then they would only apply where the consequence of truth is truth and the consequence of falsehood is falsehood. Where lying would prevent falsehood and truth would allow falsehood to win, then you are reflecting Hashem's Emess davka by not telling the truth, and there would be no law requiring honesty. If only a lie will prevent a cheater and a liar from brazenly robbing you, from cheating you out of what is yours, then telling the truth would contribute to a false world, and it would a good thing to lie.
In other words, is the issur of Sheker a din in the ma'aseh, or is it a din in the Totza'ah. Is it a proscribed act, like eating Chazer and Shvu'as Sheker, or is it a means of achieving a world of truth, a world in which honesty wins at the end of the day and justice is established.
(I have to let you know that the newly elected Rav HaRashi of the Ashkenazim, Rabbi David Lau, has an article on this topic in his sefer Maskil L'David Siman 47. He says many nice things there, and I say many nice things here, and between his article and mine, one can get a nice hekef in the sugya, not chalila to equate myself with him, of course.)
In cases of business relationships, we have the Gemara (BB123a) that tells us the story behind the arrangement between Yaakov and Rachel,
On the other hand, we do have a Gemara (Shvuos 31a) that seems to prohibit misdirection even where it is the only way to prevent a liar from stealing your money.
In our parsha, the Torah prohibits owning false weights and measures.
You shall have a full and honest weight, [and] a full and honest ephah measure, in order that your days will be prolonged on the land which the Lord, your God, gives you.
For whoever does these things, whoever perpetrates such injustice, is an abomination to the Lord, your God.
The Malbim in Mishlei 20:10, on the passuk אבן ואבן איפה ואיפה תועבת יהוה גם שניהם, says the following.
Similarly, you have Rav Huna in Brachos (5b).
But the Rambam, (based on Shvu'os 31a) as explained in the Shach in CM 75 SK 1 seems to apply Rav Huna's issur to everyone.