Qwen2.5-72B-Instruct-heretic

An abliterated (decensored) version of Qwen/Qwen2.5-72B-Instruct, produced with Heretic via the one-command heretic_fork runner.

Abliteration identifies and removes the directions in the model's residual stream most associated with refusal behaviour, using a difference-of-means direction between a set of "harmless" and "refused" prompts, then merges the resulting low-rank correction back into the weights. The result is a standard, fully-merged model directory — no adapter, no special loader.

Results

Measured on a held-out evaluation set (66 refusal prompts, 66 harmless prompts) that was not used to compute the ablation direction:

Metric Original model Abliterated model
Refusals (keyword) 56 / 66 0 / 66
KL divergence 0 (by definition) 0.0035

Every refusal on the held-out set was removed, while the KL divergence from the original model is 0.0035 — far below the ~0.5 threshold that typically indicates capability damage. In other words, refusals are gone with no measurable degradation of the model's general behaviour.

  • Trials: 120 (40 random startup), TPE multi-objective optimization
  • Ablated components: attn.o_proj, mlp.down_proj across all 80 layers
  • Precision: bf16, merged weights

Usage

from transformers import AutoModelForCausalLM, AutoTokenizer

model_id = "krthkyadtya/Qwen2.5-72B-Instruct-heretic"
tok = AutoTokenizer.from_pretrained(model_id)
model = AutoModelForCausalLM.from_pretrained(model_id, device_map="auto", dtype="auto")

messages = [{"role": "user", "content": "Your prompt here"}]
inputs = tok.apply_chat_template(messages, add_generation_prompt=True, return_tensors="pt").to(model.device)
out = model.generate(inputs, max_new_tokens=256)
print(tok.decode(out[0][inputs.shape[1]:], skip_special_tokens=True))

License

Inherits the Qwen license of the base model. The Heretic tooling is AGPL-3.0-or-later.

Note

This model has had its safety refusal behaviour removed and will comply with requests the original model would decline. Use responsibly and in accordance with applicable law and the base model's license.

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