What’s the relationship between a human’s intuitive sense of what’s moral and halachic mandate? There is a tendency in some circles to describe the Torah as though halakhah was the sum total of the guidelines Hashem gave us for behavior.
This is belied by a number of the mitzvos that require we follow some sense of “right” or “holy” that isn’t spelled out in behavioral terms. That we must know what “good” means beyond doing what is detailed through halachic methodology in order to obey them. For example “be holy, for I am Holy” which the Ramban famously tells us is an obligation not to be “disgusting with [what would otherwise be] the permission of the Torah”. By definition, the Ramban assumes there is a definition of “disgusting” that isn’t defined by halachic process. Or “and you shall do hayashar vehatov — the upright and the good” . Qedushah, yosher and tov are treated as givens, that a person is expected to know what they are before one can even begin to explore the halachic mandate.
One can accordingly translate HIllel’s famous words to the prospective ger, “That which you would loathe [if in their shoes] don’t do to others. Now go and learn” into “All of the Torah is an elaboration of natural morality. However, you would never figure out how to reach the right conclusions from those principles unless you go study Torah.”
It’s like saying that all of biology is inherent in Physics. Even that said, you would never be able to derive biology on your own. If we were to rely on our ability to build the system ourselves from the first principles we would quickly exceed human capacity; errors would necessarily be made That’s the role of halakhah, to allow us to work with notions closer to our question than the basic moral principle from which they derive.
Along similar lines is the mitzvah of “vehalakhta bidrakhav — and you shall go in My Ways”, which our sages elaborate (this version is from the Rambam, Hilkhos Dei’os 1:6) “Just as He is called ‘goodwilled’ (חנון), so too you must be goodwilled; just as He is called Merciful, so too you must be Merciful…” Hilkhos Dei’os, Chovos haLvavos — entire texts based on the notion that one must be a moral being.
The Rambam writes:
Moses prayed to God to grant him knowledge of His attributes, and also pardon for His people; when the latter had been granted, he continued to pray for the knowledge of God’s essence in the words, “Show me thy glory” ([Exod. xxxiii.] 18), and then received, respecting his first request, “Show me thy way,” the following favourable reply, “I will make all my goodness to pass before thee” (ib. 19); as regards the second request, however, he was told, “Thou canst not see my face” (ib. 20). The words “all my goodness” imply that God promised to show him the whole creation, concerning which it has been stated, “And God saw everything that he had made, and, behold, it was very good” (Gen. i. 31); when I say “to show him the whole creation,” I mean to imply that God promised to make him comprehend the nature of all things, their relation to each other, and the way they are governed by God both in reference to the universe as a whole and to each creature in particular. This knowledge is referred to when we are told of Moses,” he is firmly established in all mine house” (Num. xii. 7); that is, “his knowledge of all the creatures in My universe is correct and firmly established”; for false opinions are not firmly established. Consequently the knowledge of the works of God is the knowledge of His attributes, by which He can be known. The fact that God promised Moses to give him a knowledge of His works, may be inferred from the circumstance that God taught him such attributes as refer exclusively to His works, viz., “merciful and gracious, longsuffering and abundant in goodness,” etc., (Exod. xxxiv. 6). It is therefore clear that the ways which Moses wished to know, and which God taught him, are the actions emanating from God. Our Sages call them middoth (qualities), and speak of the thirteen middoth of God (Talm. B. Rosh ha-shanah, p. 17b)…Moshe’s ability to be the conduit for the Torah and the fountainhead for the halachic process was his being shown the morality inherent in how G-d made and runs the world.
The revalation of Hashem’s attributes was fulfilled in showing Moshe how He runs the universe. That revalation gave Moshe the ability to “walk in His ways”. But more than that, the Rambam writes later in that chapter:
By the mention of this attribute we are, as it were, told that His commandments, undoubtedly in harmony with His acts, include the death even of the little children of idolaters because of the sin of their fathers and grandfathers. This principle we find frequently applied in the Law, as, e.g., we read concerning the city that has been led astray to idolatry, “destroy it utterly, and all that is therein” (Deut. xiii. 15). All this has been ordained in order that every vestige of that which would lead to great injury should he blotted out, as we have explained.
As the Torah states
וַיֹּ֣אמֶר ה֔’ הִנֵּ֥ה מָק֖וֹם אִתִּ֑י וְנִצַּבְתָּ֖ עַל־הַצּֽוּר׃ וְהָיָה֙ בַּֽעֲבֹ֣ר כְּבֹדִ֔י וְשַׂמְתִּ֖יךָ בְּנִקְרַ֣ת הַצּ֑וּר וְשַׂכֹּתִ֥י כַפִּ֛י עָלֶ֖יךָ עַד־עָבְרִֽי׃ וַהֲסִֽרֹתִי֙ אֶת־כַּפִּ֔י וְרָאִ֖יתָ אֶת־אֲחֹרָ֑י וּפָנַ֖י לֹ֥א יֵֽרָאֽוּ׃
וַיֹּ֤אמֶר ה֙’ אֶל־מֹשֶׁ֔ה פְּסָל־לְךָ֛ שְׁנֵֽי־לֻחֹ֥ת אֲבָנִ֖ים כָּרִֽאשֹׁנִ֑ים וְכָֽתַבְתִּי֙ עַל־הַלֻּחֹ֔ת אֶ֨ת־הַדְּבָרִ֔ים אֲשֶׁ֥ר הָי֛וּ עַל־הַלֻּחֹ֥ת הָרִֽאשֹׁנִ֖ים אֲשֶׁ֥ר שִׁבַּֽרְתָּ׃
Hashem said: Here, there is a place with Me, and you shall stand on the boulder. When I pass my Glory by, I will place you in a cleft in the boulder and I will remove My “Palm” and you will see My “Back”, but My “Face” will not be seen.
Hashem said to Moshe: Carve for yourself two stone tablets like the first ones, and I will write on the tables the ideas which were on the first tablets which you shattered.
— Shemos 33:21-34:1
Natuaral moral law is expressed in halakhah. The connection is not self-evident, and in fact requires Divine Intellect to accurately get from “that which you loathe…” to the laws of making tea on Shabbos. But Hillel, the Ramban and the Rambam all tell us that our intuitive notion of right is in line with the principles of halakhah. It is from seeing Hashem’s creation that Moshe was prepared to carve the second luchos. And thus, where not contradicted by those non-obvious cases, we are required to follow natural morality. That’s qedushah, tov and yosher.