A Probabilistic Consensus-Driven Approach for Robust Counterfactual Explanations
For practitioners needing reliable explanations from black-box models, this method provides a flexible, tunable robustness control without retraining.
Counterfactual explanations often fail when models are updated. The authors propose a probabilistic consensus method using normalizing flows to generate robust CFEs, achieving superior robustness while maintaining other performance metrics.
Counterfactual explanations (CFEs) are essential for interpreting black-box models, yet they often become invalid when models are slightly changed. Existing methods for generating robust CFEs are often limited to specific types of models, require costly tuning, or inflexible robustness controls. We propose a novel approach that jointly models the data distribution and the space of plausible model decisions to ensure robustness to model changes. Using a probabilistic consensus over a model ensemble, we train a conditional normalizing flow that captures the data density under varying levels of classifier agreement. At inference time, a single interpretable parameter controls the robustness level; it specifies the minimum fraction of models that should agree on the target class without retraining the generative model. Our method effectively pushes CFEs toward regions that are both plausible and stable across model changes. Experimental results demonstrate that our approach achieves superior empirical robustness while also maintaining good performance across other evaluation measures.