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  • Rabbi Dr. Benji Levy

Can a Moral Truth Ever Change?

(First published on aish.com on the 26th of June 2022).


Can a moral truth ever change or does morality need constant upgrading to be truly moral?

Where does our sense of right and wrong come from? Are moral truths unchanging or do they shift in time along with everything else? Here’s a thought: why not both?


Two champions of pre-Socratic Greek philosophy, Heraclitus and Parmenides, provide two archetypes for understanding existence. as I shared in a previous post. According to Heraclitus, everything changes, nothing is fixed, and the only constant is flux itself. According to Parmenides, change only appears to be real but, in truth, the world is as it is, was, and will be forever because time is an illusion.

Everything changes. Or nothing changes. Which one is it? I'm going to give you the quintessential Jewish answer: Both.

After all, one of the privileges of being Jewish is holding two opposing ideas simultaneously. That’s what we do.


Here’s an example: we have a duty to try leave the world a better place than we found it. Yet, we also recognize that there is a higher, essential reality that remains constant.

Or consider the Torah: it’s the moral and spiritual north star that has guided The Jewish People for thousands of years and is a blueprint for the world's creation.1 There's nothing more Parmenidean than that. And yet the very act of learning Torah is a dynamic, ongoing process. In each generation, in every situation, the law is interpreted and applied anew to changing realities. And yet we do not interpret and apply in any way we see fit. There are strictly defined guidelines, as these sacred texts are elucidated in accordance with sacred principles with great sensitivity. Similarly, we have an Oral Tradition, a living, breathing body of knowledge that is ‘not in heaven’ 2. And we understand that we each have our own personal ‘portion’ in Torah, including unique insights and perspectives that only we can locate, connect with, and share, resonating with our own experience.


If all of this sounds a little too abstract, then let’s turn our attention elsewhere for a moment.

We are all moral agents. Whether consciously thinking about it or not, we are governed by unbending principles. Even when we seem to be acting out of pure instinct, we are guided by ethical rules.

The point is not that we always know exactly what the right thing to do is. We don’t. And yet we don’t live as nihilists. When we fail to meet our ideals (as we often do), we feel pretty bad or try to justify our actions. You don’t feel like that unless you believe there is some true standard by which conduct can be judged.

So, Parmenides is right. Moral truth – what truly matters – is constant, unchanging, and eternal. Follow God’s commandments and don’t sweat the small stuff.

Not so fast.

In reality, if most of us were asked to give a detailed account of our moral principles, we’d struggle. ‘Treat others as you would want to be treated’ feels like a solid principle, yet does it apply when it comes to punishing a murderer? And most of us feel like it’s wrong to lie, but what if the lie will prevent greater harm?


There’s the ideal of perfect care that you can philosophize and theorize about, and there’s the messy reality, where you constantly need to make difficult choices.


Or consider a doctor who has to perform triage in a crisis situation. They’ll tell you it’s not so simple. There’s the ideal of perfect care that you can philosophize and theorize about, and there’s the messy reality, where you constantly need to make difficult choices. Sometimes in choosing to help here, you inevitably cause harm there. Or think of commanders on the battlefield having to make life and death decisions that the rest of us can barely comprehend.

What happens when our immutable moral truths just don’t make sense anymore?

The answer, of course, is that the real, imperfect, and fluctuating world of Heraclitus does not render our values worthless. Rather, it’s the rigorous testing of those values that truly make them meaningful 3.


For it’s precisely in the messy world of imperfect humans trying to do their best under challenging conditions that abstract values take on any tangible form. They become, in a concrete sense, true. It’s just that those truths aren’t always what you would expect to come up with sitting in the philosopher’s armchair.


For it’s precisely in the messy world of imperfect humans trying to do their best under challenging conditions that abstract values take on any tangible form.


So Parmenides is right. There are fixed absolutes. But this fundamental reality only becomes really real when it is tested out in the world. Otherwise, it’s just a thought experiment.

Eternal truth and eternal change go hand in hand to produce a moral reality.

Returning to Jewish tradition, there’s a reason you can pick a random page of the Talmud and see our most revered and brilliant sages talking about things like the theft of sheep or how to interpret a marriage contract. These aren’t just language games. Our greatest intellectuals, thinkers, and sages with immense spiritual power are rolling up their sleeves and doing the hard work of connecting the sublime to the very, very mundane, aiming eternal, unchanging principles at a moving target. This is the difference between pure academic philosophy and lived values.

And as the facts about the mundane world continue to change, in every generation, we need to apply our minds once again to the connection between moral truth and lived reality. And it’s hard work.


So what can two of the most famous sages in Talmudic discourse, Hillel and Shammai,4 teach us about living a meaningful life in an age of thermonuclear weapons, Artificial Intelligence and social media? A lot, actually. We have an ethical obligation to take the lessons handed to us by our teachers and apply them in creative ways to our contemporary conundrums.

And even within our tradition, we won’t always agree on the fine points of practical ethics. The great battle for truth between the students of Hillel and Shammai extends to the great minds of every generation. The principle is that, somehow, through ongoing disagreement, we help each other come closer to the truth. But that’s another Jewish mystery for another time.


  1. Midrash, Bereishit Rabba 1:1; Zohar 2:161a.

  2. Bava Metzia 59b.

  3. See Talmud, Shabbat 88b-89a where Moses argues that the Torah belongs to human beings (‘walkers’) not angels (‘standers’).

  4. These philosophical sparring partners, in many respects, mirror the Parmenides-Heraclitus dichotomy. The name Shammai comes from the Hebrew word shem which means ‘name’ and in mystical teachings this expresses the totality and essence of a thing. It also comes from the word sham, meaning ‘there’, the point of destination (related to the word shamayim, ‘heavens’). Shammai (almost) always took the strict position, perhaps reflecting a world in its ideal state. Hillel on the other hand, was, in some sense, a ‘realist’ – he took the world as it was and worked from there. In describing their respective paradigms, the Talmud relates how Shammai would eat every weekday meal in honor of Shabbat by setting aside any delicacies that he came across during the course of the week for Shabbat, unless and until something even better became available, in which case he would eat the original food. For Hillel, on the other hand, everything he did – however seemingly mundane – was for the ‘sake of Heaven’: he would eat what was available to him on any given day, in the faith that he would come across fittingly choice foods with which to beautify Shabbat when the time arose.

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