Google DeepMind is calling for the moral behavior of large language models—such as what they do when called on to act as companions, therapists, medical advisors, and so on—to be scrutinized with the same kind of rigor as their ability to code or do math.

As LLMs improve, people are asking them to play more and more sensitive roles in their lives. Agents are starting to take actions on people’s behalf. LLMs may be able to influence human decision-making. And yet nobody knows how trustworthy this technology really is at such tasks.

With coding and math, you have clear-cut, correct answers that you can check, William Isaac, a research scientist at Google DeepMind, told me when I met him and Julia Haas, a fellow research scientist at the firm, for an exclusive preview of their work, which is published in Nature today. That’s not the case for moral questions, which typically have a range of acceptable answers: “Morality is an important capability but hard to evaluate,” says Isaac.

“In the moral domain, there’s no right and wrong,” adds Haas. “But it’s not by any means a free-for-all. There are better answers and there are worse answers.”

The researchers have identified several key challenges and suggested ways to address them. But it is more a wish list than a set of ready-made solutions. “They do a nice job of bringing together different perspectives,” says Vera Demberg, who studies LLMs at Saarland University in Germany.

A number of studies have shown that LLMs can show remarkable moral competence. One study published last year found that people in the US scored ethical advice from OpenAI’s GPT-4o as being more moral, trustworthy, thoughtful, and correct than advice given by the (human) writer of “The Ethicist,” a popular New York Times advice column.  

The problem is that it is hard to unpick whether such behaviors are a performance—mimicking a memorized response, say—or evidence that there is in fact some kind of moral reasoning taking place inside the model. In other words, is it virtue or virtue signaling?

This question matters because multiple studies also show just how untrustworthy LLMs can be. For a start, models can be too eager to please. Th...