An internet filter is not a stringency.
It is a halakhic obligation.

Mikhshol — The duty to remove obstacles מִכְשׁוֹל

The foundational verse, its talmudic extension, and the codification of spiritual danger by the Acharonim.

The verse "Lo tashim damim be-veitecha" (Devarim 22:8) traditionally commands building a parapet on rooftops to prevent falls. The Talmud Bava Kama (15b) extends this to any mikhshol — not merely the physical. The Shulchan Arukh codifies the extension (Choshen Mishpat 409:3), explicitly forbidding keeping a dangerous dog unleashed even when neighbors do not actually complain.

The modern question therefore arises with unusual sharpness: is a device that involuntarily exposes one to inappropriate content a mikhshol? The Shla HaKadosh (Derekh HaChayim, Tochehot Mussar, Parshat Kedoshim) rules that sokana ruchanit — spiritual danger — is equivalent to sokana gufanit for this mitzvah. The position is upheld by the Minchat Chinuch and Mahari Halevi, and forms today's Acharonim consensus.

The Rambam systematizes in Hilchot Rotzeach u-Shmirat HaNefesh (11:4): anything whose presence in one's home constitutes a danger to life is positively forbidden, and the owner violates an asseh each day he fails to remove it. The language is unambiguous — this is not stringency, but a positive obligation renewed daily.

Sokana ruchanit — the Acharonim turning point

Extending mikhshol to the spiritual is no modern innovation. The Hafetz Hayim, in his introduction to Sefer Shemirat HaLashon, applies the principle to the auditory environment. The Chazon Ish (Yoreh Deah 7:11) extends it to the visual. The logic is sealed by the Shla:

This analysis establishes that an internet filter is the direct modern application of "Lo tashim damim be-veitecha". When a documented spiritual danger exists under our roof — and the 73% involuntary-exposure figure is documented by OFCOM, by Pew, by community reports — we are obligated to act. Not as additional piety; as mitzvah min ha'din.

Darka aharina — The alternate path דֶּרֶךְ אַחֶרֶת

The Bava Batra 57b sugiya and its application to contemporary technological choice.

The sugiya in Bava Batra (57b) treats a man who must cross a quarter where women launder at the river. The Gemara debates whether such exposure is bearable when unavoidable — and rules: if an alternate path exists and he nonetheless takes the first, he is called rasha. The wording is hard. The Gemara does not write that he "lacks piety" or "could do better." It writes rasha.

The Rashbam, ad loc., explains that the principle does not depend on intent or outcome — it depends only on the existence of the alternative. If the alternative exists and is not significantly more costly, refusing it is itself a transgression. The Tur (Even HaEzer 21) takes up this codification and extends it to choice of work environment, neighborhood, and — as modern Acharonim apply it — to technological choice.

The modern application follows rigorously. If a technological alternative exists — a filter, a restricted mode, a dedicated device — one is obligated to take it rather than "test one's will" by remaining exposed. The principle expressly prohibits the posture of "I'll resist by force of character." The Rosh, in his comments on the sugiya, is sharper still: force of character is not the way of halakha when a practical alternative exists.

The cost-benefit argument that once justified not requiring a filter — "it blocks too many useful things" — has become obsolete as filtering technology has matured. When the alternative exists, is accessible, and imposes no significant cost on professional or domestic life, refusing it falls directly under the sugiya's verdict.

Nisayon — Not placing oneself in trial נִסָּיוֹן

Sanhedrin 107a, the David HaMelech sugiya, and its application to digital environments.

The sugiya in Sanhedrin (107a) recounts that David HaMelech asked HaKadosh Baruch Hu why we say in the Amida "Elokei Avraham, Elokei Yitzhak, Elokei Yaakov" but not "Elokei David." The divine reply, in the Gemara's reading, is that the patriarchs were tested (nisayon) and held — David had not been. David asks for the trial. He receives it. And the Gemara concludes, in language that has become classic in mussar literature, that David regretted having asked.

The halakhic lesson drawn by the Rishonim and reaffirmed in the Mesilat Yesharim (chapter 9) is unambiguous: even the tzaddikim must avoid avoidable nisayon. Piety is not the seeking of trial — it is its prevention. The baal nefesh who deems himself above nisayon, and exposes himself voluntarily under pretext of self-testing, acts against halakha, not for it.

The modern application is plain. An unfiltered device, in 2026, is a distributed nisayon environment: algorithms optimize for retention — that is, for the content that holds the eye, in other words for the mikhshol. Even a responsible adult, even a baal nefesh, must configure his environment so as not to test himself unnecessarily. The filter is no admission of weakness — it is the strict application of Sanhedrin 107a.