Re`eh #3: How can you tell if a prophet is false?

This is in response to a query by Dov, so here is my response.

There are two ways. First, you can tell by the message. If a prophet tries to tell you to serve avodah zara, this is explicit in the parsha that he is a false prophet, to be killed. Further, Chazal make a diyuk (you can see it in the Sifrei if you have it in your mikraos gedolos) that if a prophet tries to change the existing corpus of dinim diorayta, and this means on a permanant basis, not as a horaat shaah, temporary emergency basis, then he is a false prophet. If one the other hand the prophet tells you to do tshuva and to serve Hashem, he is probably a true prophet. (See Yirmiyahu 28:8, and see how this can be derived from there.)

Second, if he claims something will happen and it does not. The restriction on this is that if was something bad, Chazal say (in some opinions at least) that Hashem could change his mind if the people do tshuva, so this is a warning, and then the person is not a false prophet. A good example would be Yonah, who prophesied the fall of Ninveh, and they did tshuva and it was not destroyed. Yonah feared, though, that people would wrongly suspect him of being a false prophet (according to some, that is why he did not want to go to Ninveh in the first place).

However, if a prophet prophesies about good to come, Hashem will not retract (this on the basis of various psukim.) If you check out Yirmiyahu 28th perek, Yirmiyahu has a showdown with Chanania ben Azur, where Yirmiahu predicts doom and gloom as per usual, while Chanania predicts redemption. Yirmiyahu's statement to Chanania may very well be (and is, according to some meforshim) that Yirmiyahu cannot in this instance be shown false, since failure to occur might come as a result of tshuva, and as such he hoped Chanania's prophecy would come true. However, Chanania has much to lose, and his status as a prophet is as stake.

Specifically, look at psukim 8 and 9:

8: The prophets that have been before me and before thee of old prophesied against many countries, and against great kingdoms, of war, and of evil, and of pestilence.


That is, they, like I have said bad things.


9: The prophet that prophesieth of peace, when the word of the prophet shall come to pass, then shall the prophet be known, that the LORD hath truly sent him.'


In Hebrew:
הַנְּבִיאִים, אֲשֶׁר הָיוּ לְפָנַי וּלְפָנֶיךָ--מִן-הָעוֹלָם: וַיִּנָּבְאוּ אֶל-אֲרָצוֹת רַבּוֹת, וְעַל-מַמְלָכוֹת גְּדֹלוֹת, לְמִלְחָמָה, וּלְרָעָה וּלְדָבֶר.

הַנָּבִיא, אֲשֶׁר יִנָּבֵא לְשָׁלוֹם--בְּבֹא, דְּבַר הַנָּבִיא, יִוָּדַע הַנָּבִיא, אֲשֶׁר-שְׁלָחוֹ יְהוָה בֶּאֱמֶת.

That is, such a prophet can be subject to a test, for he prophesied good to come, which Hashem will not retract from.

Others, of course, explain these psukim differently.

The final caveat is that a person communication between Hashem and a prophet not intended for public consumption might not come true, if merits are decreased and it is no longer deserving. The idea is that Hashem will not play with the minds of the masses, offering them false hope only to dash it, so good in a public prophecy will not be undone, but in a private prophecy Hashem would. Thus, Yaakov was afraid when Esav approached with 400 men, even though he had a previous promise from Hashem, since perhaps his merits had been exhausted.

The above is all based on the Rambam.