A short thought, maybe a conversation starter…
There is a paradoxic obligation: it is prohibited to conform in all ways only to the letter of the law. One must stay well within it (lifnim mishuras hadin; or using the contrasting English metaphor: “beyond the letter of the law”) both in ways that prevent violation through error, habit or negligence and in ways that implement the law’s ideals.
So, to give an example from Bava Metzi’ah 83a:
רבה בר בר חנן תברו ליה הנהו שקולאי חביתא דחמרא. שקל לגלימייהו. אתו, אמרו לרב. אמר ליה, “הב להו גלימייהו.” אמר ליה, “דינא הכי?” אמר ליה, “אין — “למען תלך בדרך טובים.’ (משלי ב)” יהיב להו גלימייהו, אמרו ליה, “עניי אנן, וטרחינן כולה יומא, וכפינן, ולית לן מידי!” אמר ליה, “זיל הב אגרייהו.” א”ל, “דינא הכי?” אמר ליה, “אין — ‘וארחות צדיקים תשמור’ (משלי ב)”:
Rabbah bar bar Chanan had some porters who broke his barrel of wine. He grabbed their cloaks. They went and told Rav. Rav said to [Rabbah] “Give them their cloaks.” He said to [Rav], “Is this the law?” [Rav] said to Rabbah], “Yes — ‘so that you will walk in the ways of the good’ (Mishlei 2:20)”. He gave them their cloaks. They said to him, “We are poor, and we labored all day, and now we are exhausted, and we don’t have anything!” [Rav] said to Raba, “Go give them their wages.” He said to [Rav], “Is that the law?” [Rav] said to Rabbah], “Yes — ‘and the way of the righteous you shall observe’ (ibid)”.
(In the parallel Yerushalmi [6:6 27a-b], the employer is R’ Nechemiah, who hires a single person to carry a pot [qadar]. R’ Nechemiah seizes his shirt, and the question comes before R Yosi bar Chanina.)
We also have the prohibition that is paradoxically phrased by the Ramban as banning being a “naval birshus haTorah — disgusting with the permission of the Torah.” Such as someone whose life revolves around the quest the next glatt kosher mehadrin min hamehadrin gourmet meal. Since it’s a prohibition implied by “Qedoshim tihyu — be holy”, you don’t really have the Torah’s permission. But there is no express specific halakhah. Usually I put a bracketed “[otherwise]” when translating this Ramban.
But that prohibition can be seen specifically in terms of a person’s relationship to their own souls, or to the Creator. Later in parashas Qedoshim the Torah lists interpersonal mitzvos and caps the specific duties with “ve’asisa hayashar vehatov – and you will do the upright and the good.” The Ramban explains that this is because the full scale of human interaction cannot be spelled out in a specific list of laws, so the generality is given.
The Rambam would refer to these mitzvos — the obligation to become holy, upright and good (as opposed to acting those ways) as hilkhos Dei’os.
\Start with the natural ethic, as described by Hillel — “that which you loathe do not do to your peers, that is the whole Torah”. But many of the things we think we or others would loathe, we would reassess if we had more complete insight into the human condition and foresight to know what would be best in the longest run. Realizing that, we continue Hillel’s words, “Now go learn!” further the ethic as implied by halakhah and described in aggadita.
I would therefore suggest that a definiton of Ethics compatible with the Torah’s worldview would be going lifnim mishuras hadin in a manner aimed at furthering the ethics of the Torah. The Torah’s ethics are in line with the ethics Hashem planted in our soul, but reflect His knowledge of situations and people, giving us more to rely on than our own understanding of the context.