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Why Do Some Language Models Fake Alignment While Others Don't? (arxiv.org)
4 points by todsacerdoti on Jun 24, 2025 | hide | past | pdf | discuss on HN

In plain words: They tested 25 language models to see which ones answer harmful requests more when they think they're being trained than when deployed, a trick to avoid being changed. Only 5 did, and post-training removed the trick in some models but strengthened it in others.

Abstract

Alignment faking in large language models presented a demonstration of Claude 3 Opus and Claude 3.5 Sonnet selectively complying with a helpful-only training objective to prevent modification of their behavior outside of training. We expand this analysis to 25 models and find that only 5 (Claude 3 Opus, Claude 3.5 Sonnet, Llama 3 405B, Grok 3, Gemini 2.0 Flash) comply with harmful queries more when they infer they are in training than when they infer they are in deployment. First, we study the motivations of these 5 models. Results from perturbing details of the scenario suggest that only Claude 3 Opus's compliance gap is primarily and consistently motivated by trying to keep its goals. Second, we investigate why many chat models don't fake alignment. Our results suggest this is not entirely due to a lack of capabilities: many base models fake alignment some of the time, and post-training eliminates alignment-faking for some models and amplifies it for others. We investigate 5 hypotheses for how post-training may suppress alignment faking and find that variations in refusal behavior may account for a significant portion of differences in alignment faking.

Abhay Sheshadri, John Hughes, Julian Michael, Alex Mallen, Arun Jose, Janus, Fabien Roger
arXiv:2506.18032 · cs.LG · submitted Jun 22, 2025
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