halacha - Is there a problem with lying?

Is lying per se forbidden? If not, are there circumstances under which (certain lies) are forbidden? On what grounds?

What about:

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  If you have a good enough reason to lie (e.g. for the sake of a mitzvah -- For example, could I say I was sick so as not to shake someone's hand?) -- or generally to avoid harm?

  
  


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  If the addressee were a minor?

  
  



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  If the addressee were not Jewish?

  
  

Answer

See Gemara BM 23b

For Rab Judah said in the name of Samuel:

In the following three matters learned men do conceal the truth:




1. In matters of a tractate {they ask know you this Massechet at your fingertip and by humility he says "No!" (Rashi)},


2. bed {If they ask if he has a sexuel intercourse, he can hive a negative answer, even if it is not true, by modesty (adapted from Rashi), If he comes later to the study because of Tevilat Ezra, he can give a false explanation to his delay},


3. hospitality {If they ask about the quality of the accomodation provided by its host, he can protect him against a large inflow of profiteers (adapted from Rashi)}.

What is the point [in this observation]? - Mar Zutra said: [It is important in regard to the question] of returning a lost article, [recognised] by sight: If we know that [the claimant] conceals the truth those three matters only we give it back to him, but if he does not speak the truth also in other matters we do not give it back to him.

See Yevamot 65b:

1. Rabbi Ile'a further stated in the name of Rabbi Eleazar son of Rabbi Simeon: One may modify a statement in the interests of peace; for it is said in Scripture, Thy father did command etc. so shall ye say unto Joseph: Forgive, I pray thee now, etc.{Yaakov do not order but they change in the interest of peace (Rashi)}


2. Rabbi Nathan said: It is a commandment; for it is stated in Scripture, And Samuel said: 'How can I go? If Saul hear it, he will kill me', etc. {G_d commanded him to change and to take a calf and to lie}



3. At the School of Rabbi Ishmael it was taught: Great is the cause of peace. Seeing that for its sake even the Ho One, blessed be He, modified a statement; for at first it is written, My lord being old, while afterwards it is written, And I am old. {Sarah spoken with disdain about Avraham}

The first Gemara enumerates current situations, the third case is also for reason of peace. The second Gemara gives examples of great people and G_d itself. You can see two examples of harm (Shmuel, see Nazir chapter 9, Mishna 5 "אָמַר לוֹ רַבִּי נְהוֹרַאי, וַהֲלֹא כְבָר נֶאֱמַר (שמואל א טז) וַיֹּאמֶר שְׁמוּאֵל אֵיךְ אֵלֵךְ וְשָׁמַע שָׁאוּל וַהֲרָגָנִי, שֶׁכְּבָר הָיָה עָלָיו מוֹרָה שֶׁל בָּשָׂר וָדָם", R Nehorai said to him: but does it not also say, and samuel said; 'how can i go? if Saul hear it he will kill me' [which shows] that he was in fact afraid of a human being?)