Gemara

3b (Beraisa): Who is considered a Shoteh (lunatic)? This is one who goes out at night alone, spends the night in the cemetery, and tears his garment.

(Rav Huna): One is a Shoteh only if he does all of these together;

(R. Yochanan): He is a Shoteh even if he does one of them.

Question: What is the case?

If he does them like a lunatic, (all should agree that) even one suffices!

If he does not do them like a lunatic, even all should not suffice!

Answer: Really, he does them like a lunatic. (Nevertheless, there are other ways to explain these behaviors:)

Perhaps he spends the night in the cemetery so that Ru'ach ha'Tum'ah will rest on him;

Perhaps he goes out at night alone (to cool off) because he is overheated;

Perhaps he tears his garment because he is bewildered.

If he does all of them, this is like an animal that gored an ox, donkey and camel; it is Mu'ad to gore all animals.

Rav Papa: Had Rav Huna heard the following Beraisa, he would have retracted:

(Beraisa): A Shoteh is one who destroys what people give to him.

Question: Does Rav Papa mean that he would have retracted from saying that tearing his garment does not suffice by itself, for this is similar? Or, would he have retracted totally (and agreed with R. Yochanan)?

This question is not resolved.

Gitin 71a (Beraisa): Regarding Metaltelim we rely on gestures and facial expressions of a Cheresh and what he writes, but not for Gitin.

R. Shimon ben Gamliel says, this applies only to one who was deaf from birth, but if a hearing man became deaf, he writes (a Get) and witnesses sign it.

(R. Yochanan): Chachamim (the first Tana) argue with R. Shimon ben Gamliel. (They say that if a healthy man married and became deaf, he cannot divorce even if he can write.)

Support (Abaye - Mishnah): If a husband went deaf or insane, he may never divorce his wife.

Suggestion: It says never to include even if he can communicate through writing!

Rejection (Rav Papa): Perhaps R. Shimon ben Gamliel explains the first Tana. The Mishnah says 'never' to include even if he is very sharp.

Bava Basra 155b: A man sold his father's property during the year (at the end of which a Seris may sell his father's property, i.e. 18 or 20). Rava nullified the sale.

Suggestion: This shows that a sale during the year is invalid!

Rejection: We cannot learn from this. Rava saw that he was acting excessively foolishly; he freed his slaves.

Nidah 13b (Mishnah): If a Kohenes is insane... or went crazy, healthy women check and immerse her, so she can eat Terumah.

Question: One who went crazy is insane! (Why are they listed separately?)

Answer: She went crazy due to sickness.

Rishonim

Rambam (Hilchos Edus 9:9): A Shoteh is Pasul for testimony mid'Oraisa for he is exempt from Mitzvos. This is not only a lunatic who walks around naked and breaks Kelim and throws rocks. It is even one who went crazy and his mind is always erratic even in one matter. Even if he converses normally about other things, he is Pasul and is considered a Shoteh.

Kesef Mishneh: It is clear from the Gemara that we do not discuss one who does one of these matters once, rather, one who regularly does one. The Rambam adds one who went crazy. He understands that the Beraisa is not an exhaustive list. Rather, it gives examples; the same applies to anything that Shotim regularly do. This is why the Rambam did not list everything in the Beraisa.

Rosh Chulin (1:4): A Shoteh is one who goes out at night alone, spends the night in the cemetery, and tears his garment. A Beraisa teaches that it is one who destroys what people give to him. R. Yochanan taught that this is even if he does one of these things like a lunatic. The Halachah follows him.

Poskim

Shulchan Aruch (YD 1:5): A Shoteh is one who goes out at night alone or tears his garment or spends the night in the cemetery or destroys what people give to him. This is if he does even one of these like a lunatic. L'Chatchilah, we do not give to him to slaughter.

Beis Yosef (EH 119 DH v'Rabbeinu Simchah): R. Simchah says that one is not considered a Shoteh who cannot divorce unless he shows the Simanim in Chagigah. The Yerushalmi connotes that he must show all of them, unlike the Bavli. The primary sign is getting rid of all his property, like the man who freed all his slaves (Bava Basra 155b). Until we see this, we need not check him. We assume that he is a Pike'ach (sane).

Chasam Sofer (EH 2:2 DH Adayin): The Yerushalmi says that Rav Huna requires all of them, but it agrees that R. Yochanan requires only one! It seems that R. Simchah holds that it refers only to destroying one's clothing, which is a great lunacy.

Beis Yosef (121 DH v'Lich'orah): It would have seemed that only one who does one of the four things listed is a Shoteh. It seems that the Rambam explains otherwise because the first Beraisa listed only three things, and the latter Beraisa listed only breaking what people give to him. We must say that both of them only give examples. This is unlike R. Simchah.

Beis Yosef (DH uvi'Teshuvos): Regarding a Get, Rabeinu Avigdor wrote that if the woman did not do the things mentioned in Chagigah, she is like a Pikachas. The Maharik (19) said 'this connotes that the behaviors listed are not just examples. However, if she is exceedingly crazy like the matters listed (she is a Shotah).' The Rivash (468 DH Davar) says that one who willingly gets rid of all his property is a Shoteh, like the man who freed all his slaves.

Note: Our text (Bava Basra 155b) does not say 'all'. R. Gershom (top of the inside column) says that Rava considered him like a child because he acted foolishly, but had he brought two hairs the sale would be valid. The Gemara in Gitin (68b) says that a lunatic does not persist in only one absurdity. However, the Rashba (Megilah 15a DH Mah) says that we do not ask questions from Agados.

Shulchan Aruch (CM 35:8): A Shoteh is Pasul for testimony. This is not only a lunatic who walks around naked and breaks Kelim and throws rocks. If it even one who went crazy and his mind is always erratic even in one matter. Even if he converses normally about other things, he is Pasul and is considered a Shoteh.

Gra (14): If he is sometimes sane he is not (always) a Shoteh, like we find regarding Bar Shatya (Kesuvos 20a).

Igros Moshe (EH 1:120): It seems that one who is a Shoteh in only one aspect is considered a Pike'ach. Tosfos (Chagigah 3b DH Derech) holds that even if he does all three things, if he is a Pike'ach in other ways he is like a Pike'ach for those matters. The Rambam seems to say that he is a Shoteh. Perhaps he means that one who is a Shoteh in one aspect is assumed to be a Shoteh in every respect, but he agrees that if we see that he does things with Chachmah he is a Pike'ach. The Tevu'os Shor connotes that one cannot be a Shoteh only in some respects. We see such people. It is unreasonable to say that they are total Pikchim. It seems that the Rambam brought the definition of Shoteh regarding testimony because since lunacy exempts him from testimony, he is exempt from all Mitzvos. However, this does not mean that he cannot make Kinyanim or be a Shali'ach.

Sha'agas Aryeh (Hosafah b'Sof ha'Sefer Siman 2): Regarding testimony, the Tur and Acharonim cite the Rambam, but regarding Shechitah they and the Rosh bring the Simanim listed in Chagigah! They connote that the Simanim apply only to Shechitah.