Mitzvah # 387 in the Sefer Hachinuch is not to go astray towards heresy and licentiousness. In that mitzvah, the Sefer Hachinuch writes the following line:
ענין לאו זה שנמנענו שלא ניחד מחשבותינו לחשוב בדעות שהם היפך הדעת שהתורה בנויה עליו לפי שאפשר לבוא מתוך כך למינות
The nature of this prohibition is that we are prevented from directing our thoughts to think about ideas that are contrary to the ideas that the Torah is built upon, because it is possible to come from this to heresy.
This seems to be saying that there is a prohibition of thinking about things that might lead to heresy, because they might lead to heresy. I.e. this mitzvah is designed to prevent one from reaching heresy. This implies that the intermediate step – thoughts about ideas contrary to the ideas the Torah is built upon – is not actual heresy. I.e. thinking things contrary to the Torah foundations may lead to heresy but is not itself heresy.
In the second Beiur Halacha (ד"ה הוא) R. Yisrael Meir Kagan quotes the Sefer Hachinuch about Six Constant Mitzvos, of which mitzvah # 387 is the sixth. In his quote for this mitzvah he writes:
ובכלל אפיקורסות הוא כל מחשבות זרות שהם היפך דעת התורה
And included in heresy are any foreign thoughts that are contrary to the view of the Torah.
This does not seem to be an accurate quote/paraphrase of the Sefer Hachinuch on two counts.
- The Beiur Halacha claims that these thoughts are themselves heretical, while the Sefer Hachinuch only says that they lead to heresy.
- The Beiur Halacha seems to include anything that goes against any Torah idea, whereas the Sefer Hachinuch only mentions things that go against the Torah's foundational ideas.
Did R. Yisrael Meir Kagan believe that the Sefer Hachinuch is in consonance with what he wrote? If yes, what is the explanation? If not, why does he claim that he is quoting/paraphrasing the Sefer Hachinuch when he is in fact expanding on the ideas mentioned in the Sefer Hachinuch?
ובכלל מינות הוא כל מחשבות זרות שהם היפך דעת התורה
It is thus possible that the Beiur Halacha's interpretation was influenced by the Chayei Adam, or he remembered the Chayei Adam's formulation instead of the Sefer Hachinuch's formulation, or he was actually quoting the Chayei Adam (he does say to look at the Chayei Adam who speaks at length about this "ועיין בח"א כלל א' שהאריך ג"כ בהם"). This third option is perhaps less likely because he says at the end of the paragraph that he took everything from the Sefer Hachinuch "כ"ז לקטתי מלשונו הנחמד בקצרה", and, moreover, in Shemiras Halashon (2:2) R. Yisrael Meir Kagan discusses this idea again, and he explicitly attributes this very line to the Sefer Hachinuch:
וכתב החינוך שבכלל מינות הוא כל מחשבות שהם היפך דעת התורה
Regardless, the question still stands – where did either the Beiur Halacha/Shemiras Halashon or the Chayei Adam derive this expansion from?
Interestingly, in the Aruch Hashulchan that contains footnotes with the rulings of the Mishnah Berurah that diverge with those of the Aruch Hashulchan, this Beiur Halacha is cited as follows:
ובבה"ל (ד"ה הוא) כתב דבכלל מינות ואפיקורסות הוא כל מחשבות זרות שהם היפך דעת תורה
I don't know if this was deliberate or not but as you can see they left out the "ה" in התורה so that now it reads דעת תורה (instead of דעת התורה as it was in the Beiur Halacha), which in contemporary times can have an entirely different connotation. (I.e it can be read as saying that anything that goes against Da'as Torah is heretical.) This would be an even greater expansion of the Sefer Hachinuch.
I looked through approximately 50 sefarim that quote the Beiur Halacha, Shemiras Halashon, or Chayei Adam, and not one of them noted this issue. In fact, one of them actually said "these are the words of the Sefer Hachinuch in his introduction..." but then just cited the Beiur Halacha:
ז"ל החינוך בהקדמתו שלא נתור אחר מחשבת הלב וראיית העיניים ולא תתורו אחרי לבבכם וגו' ואמרו חכמים אחרי לבבכם זו אפיקורסות עיניכם זו זנות ובכלל אפיקורסות הוא כל מחשבות זרות שהם היפך דעת התורה מובא בביאור הלכה סימן א