Gemara

3a (Rav Idi bar Avin citing R. Yochanan citing R. Yosi ha'Glili): If one transgressed any Lav of the Torah without an action, he is not lashed, except for swearing falsely, Temurah, and cursing someone with Hash-m's name.

3b - R. Yochanan (to a reciter of Beraisos): Do not include Temurah (among the exceptions), for his words do an action (they are Makdish an animal).

17a (R. Yochanan): If one intended to say "Temuras Olah," and mistakenly said "Temuras Shelamim", Temurah takes effect.

Sanhedrin 65a - Question: Why does our Mishnah mention both Ov and Yid'oni (regarding stoning), and the Mishnah in Kerisus teaches only Ov?

Answer #1 (R. Yochanan): Since one Lav forbids both of them, there is only one Kares (if one did both b'Shogeg in one He'elem, he brings only one Korban).

Answer #2 (Reish Lakish): Yid'oni is not Chayav Kares because it is done without an action.

65b - Question: Why does R. Yochanan consider bending one's stature to be an action, but not moving one's lips (blasphemy)?

Answer (Rava): Blasphemy is not considered an action because it depends on one's intention.

Objection (R. Zeira - Beraisa): Zomemim witnesses are excluded (from bringing a Chatas) because they do not do an action.

False testimony does not depend on one's intention!

Answer #1 (Rava): False testimony is different because it depends on voice.

Rejection: R. Yochanan considers voice like an action!

(R. Yochanan): If one used his voice to muzzle an animal (he shouted at it when it wanted to eat), he is liable;

(Reish Lakish): He is exempt.

R. Yochanan holds that moving one's mouth is an action. Reish Lakish disagrees.

Answer #2 (Rava): False testimony is different because it depends on what they (claimed to, but did not) see (i.e. inaction).

Bava Metzi'a 90b - Question (R. Yochanan - Mishnah): If one made Temurah, he is lashed.

Answer (Reish Lakish): That is according to R. Yehudah, who says that one is lashed even for a Lav without an action.

Shabbos 103a (Mishnah): If one writes two letters of any language he is liable, whether he used his right or left hand, whether he wrote the same letter twice or two different letters, even if he wrote two symbols.

R. Yosi says, one is liable for two letters due to Roshem (marking). They would write letters on the Kerashim to know how to pair them up.

Question: Why is he liable for writing with the left hand? This is abnormal!

Answer #1 (Abaye): The Mishnah discusses an ambidextrous person.

Answer #2 (Rav Yakov brah d'Vas Yakov): Our Mishnah is like R. Yosi, who obligates for two letters due to Roshem.

103b (Beraisa - R. Yehudah): Even if he wrote two identical letters and they are a word he is liable, e.g. Shesh, Tes, Rar, Gag, Chach.

110b (Mishnah): If one wrote two letters using ink, Sam..., or anything that marks, he is liable;

If he wrote with liquids, e.g. fruit juice... or anything that does not last, he is exempt.

Rishonim

Rambam (Hilchos Shabbos 11:10): If one writes the same letter twice and it is a word, e.g. Tat, Gag... he is liable. One who writes in any character set in any language is liable, even for two Simanim.

Rambam (17): Roshem is a Toldah of writing. If one made marks and forms on a wall or lacquer or similar matters, like artists do, he is liable for writing. If one erases it for a constructive purpose, this is a Toldah of erasing, and he is liable.

Magid Mishneh: In the Mishnah, R. Yosi says that one is liable for writing two letters due to Roshem, which is a Toldah of writing. Perush ha'Mishnayos says that R. Yosi holds that it is a separate Av, and the Halachah does not follow him.

Question (Bi'ur Halachah 240:5 DH Mutar): Writing two letters is proper writing. It is not just a Toldah! The Gemara inferred from R. Yosi's ruling that two letters is liable only for Roshem, that he obligates also for two scratches. Since the Rambam rules unlike R. Yosi, there is no source to obligate for Roshem. They wrote letters on the boards of the Mishkan! The Rambam says that an example of Roshem is drawing pictures; he does not mention mere scratches. In Halachah 10, he obligates for two letters only if they are a word. If he obligates for markings, all the more so for any two letters! All the Tana'im who exempt for Aleph Aleph must exempt Roshem.

Aruch ha'Shulchan (340:19): R. Yosi obligates one who writes two letters for Roshem. The Rambam says that Roshem is a Toldah. This shows that he rules unlike R. Yosi, who says that it is an Av. Also, R. Yosi obligates for any marks, even if they are not pictures. However, the Yerushalmi connotes that the Halachah follows R. Yosi. The Pnei Moshe says that the Rambam rules like R. Yosi, since he obligates for Roshem. This is wrong. The Rambam obligates only for pictures. Also, Perush ha'Mishnayos explicitly says that the Halachah does not follow R. Yosi!

Question: R. Yochanan says that contorting one's lips is an action, but he also says that swearing, Temurah, and cursing are Lavim she'Ein Bahem Ma'aseh!

Answer (Tosfos Bava Metzi'a 90b DH R. Yochanan): R. Yochanan said that it is an action only because he accomplished something, i.e. he caused the animal to thresh without eating. Likewise, R. Yochanan calls Temurah a Ma'aseh, because his words do something.

Avnei Nezer (CM 145): Reish Lakish exempts one who muzzles through voice. R. Yochanan challenged him from Temurah. It is easy to distinguish these! (Temurah makes Kedushah.) I answer based on the Ran (Sukah 14a), who permits one who vowed not to benefit from a spring to immerse in it, even if it is Gorem (causes) him to become Tahor. Why is it only Gerama? The Tevilah is Metaher! Rather, the water itself is not Metaher, just Hash-m decreed this. Similarly, if one intended to say "Temuras Olah," and mistakenly said "Temuras Shelamim", Temurah takes effect. It is not due to his Ko'ach (power), for he did not intend for this at all! Rather, it is a Gezeras ha'Kasuv. His words merely cause this. (Similarly, Yitzchak's Berachah to Yakov was the conduit for him to be blessed, even though he did not intend for him at all.) Tosfos (Eruvin 102a DH Lo) says that an Ohel (tent) through Lavud (we ignore gaps less than three Tefachim) is not considered an Ohel. I.e. it is a Gezeras ha'Kasuv; he only caused it. It is as if the Torah helped. We learn from winnowing (one throws grain, and the wind removes the chaff) that the Torah forbids to do Melachah with help of the wind. The same applies when a Gezeras ha'Kasuv helps.

Question: In Sanhedrin, the Gemara proved from muzzling that R. Yochanan holds that voice is an action, and asked why he says that blasphemy and Edim Zomemim have no action. Muzzling is different, for his voice accomplished something!

Answer (Tosfos): Really, the question was only regarding Edim Zomemim, for also they accomplish through their voice. Once the Gemara answered that it depends on voice, we retract from saying that it depends on intent.

Poskim

Shulchan Aruch (OC 306:11): One may buy a house in Eretz Yisrael from a Nochri on Shabbos, and sign and go to court.

Rema: This refers to the Nochri court, in their writing, which is only an Isur mid'Rabanan. Chachamim did not decree if it will inhibit settlement of Eretz Yisrael.

Shulchan Aruch (340:3): One who rubs out ink on a parchment or wax on a tablet, if there is in its place room to write two letters, he is liable.

Shulchan Aruch (5): One may make a mark with his fingernail on a Sefer, for this does not last.

Bi'ur Halachah (DH Mutar): The Bach and Taz questioned this from the Mishnah (110a). If one is liable for a marking that lasts, such a marking that does not last must be forbidden mid'Rabanan, like we say in that Mishnah about writing! The Bach forbids, and the Magen Avraham brings this. The Taz elaborated to defend the Shulchan Aruch, with difficulty. Eliyahu Rabah explains correctly that the Tur rules unlike R. Yosi, so one is exempt for Roshem. Clearly, the Rif, Rosh, Rambam and R. Yerucham hold like this, for they exempt one who wrote with his weak hand, unless he is ambidextrous, unlike R. Yosi. The Mechaber rules like this, but the Darchei Moshe is concerned for R. Yosi. If so, one who fears Shamayim should not mark with something that does not last.

Beis Yitzchak (2 YD Maftechos 31): One may not speak near a recorder (that makes a record, like a tape recorder). He causes Roshem, and this is like writing. If one scrapes wax off a tablet, he is liable for erasing. Likewise, one who writes on wax is liable.

Yabi'a Omer (4 YD 20:7): Why does Beis Yitzchak obligate? He does not do an act with his hands, only through his breath. This is not a proper action! He must hold that contorting the lips is a proper action, like Tosfos says. Hilchos Ketanos and Yehudah Ya'ale say similarly. However, Melachos of Shabbos must be like in the Mishkan. Since they did not write there with their mouths in the Mishkan, one is exempt!

Yabi'a Omer: Beis Yitzchak holds that even though there is no form of letters, this is like writing. Surely he obligates also for erasing, and if there are names of Hash-m, one is liable for erasing Hash-m's name. This is difficult, for many Poskim exempt on Shabbos for writing anything other than Ashuris (the characters used in a Sefer Torah), and forbid only mid'Rabanan! The Rema rules like them. Even according to the opinion that obligates for any writing, this is only for something that one who knows the language can read. No one can read the fine scratches on a record. Presumably, all exempt for writing. Perhaps Beis Yitzchak holds that the Rambam includes this in "if one made marks and forms on a wall or lacquer or similar matters, like artists do, he is liable for writing." However, if so, why does the Rambam exempt one who writes Aleph Aleph? This is not less than markings! Rather, the Rambam obligates only for pictures, like the Yerushalmi says. It seems that there is no Chiyuv mid'Oraisa, for this is not writing. There was nothing like this in the Mishkan.