Why the alignment gap always wins, unless you know where to look

ai-alignment
rlhf
learning-theory
When human feedback is subtly wrong on rare cases, learning the true objective takes exponentially many samples. A calibration oracle that flags the unreliable cases collapses that cost to polynomial.
Author

Madhava Gaikwad

Published

September 5, 2025

Landscape with the Fall of Icarus, after Pieter Bruegel the Elder (16th century). Public domain, via Wikimedia Commons.

Reinforcement learning from human feedback is the standard way to align a model. People compare model outputs, the comparisons train a reward model, and the model is tuned to score well on that reward. The whole scheme rests on the feedback being right. This paper studies what happens when it is not.

A compass that points wrong in some places

The setup is misspecified feedback. Human feedback is systematically wrong on certain kinds of input. A useful picture is a compass that points true almost everywhere but points the wrong way in a few specific regions. The problem is not random error, which averages out. It is consistent error in particular places.

Two numbers describe how bad it is. One is the fraction of contexts where the feedback is biased. The other is the strength of that bias. The trouble lives in the corner of the input space where both are nonzero.

The hard result

The paper proves a lower bound. Suppose two candidate reward functions agree everywhere except on the biased contexts. To tell them apart from feedback alone, any learning algorithm needs a number of samples that grows exponentially in the prevalence of the bias and the square of its strength. Rare edge cases with subtly wrong feedback create a learning problem that is exponentially hard. You can pour in data and still not know which objective you are actually optimizing.

This is the sense in which the gap always wins. The gap is the distance between what you optimize, a proxy built from human feedback, and what you actually want, the true objective. When the problematic contexts are rare and the feedback there is quietly biased, no amount of ordinary data closes that gap.

The way out

There is one escape, and it is specific. Suppose you have a calibration oracle, a way to identify where the feedback is unreliable. Then you can spend your limited questions on exactly those contexts. The paper shows that this collapses the cost from exponential to polynomial. You no longer need to find the needle by luck, because you have been told which haystack it is in.

The lesson is practical. Throwing more feedback at an aligned system does not help where the feedback itself is broken. Finding and targeting the broken regions does.

What is settled and what is open

The results are theoretical. The paper proves the lower bound and the oracle speedup. It invites collaboration on large-scale experiments and on building the benchmarks that would test these effects in practice.

Read the paper

Murphy’s Laws of AI Alignment: Why the Gap Always Wins (arXiv:2509.05381).