Model Multiplicity: Opportunities, Concerns, and Solutions
Open accessAbstract
Recent scholarship has brought attention to the fact that there often exist multiple models for a given prediction task with equal accuracy that differ in their individual-level predictions or aggregate properties. This phenomenon---which we call model multiplicity---can introduce a good deal of flexibility into the model selection process, creating a range of exciting opportunities. By demonstrating that there are many different ways of making equally accurate predictions, multiplicity gives model developers the freedom to prioritize other values in their model selection process without having to abandon their commitment to maximizing accuracy. However, multiplicity also brings to light a concerning truth: model selection on the basis of accuracy alone---the default procedure in many deployment scenarios---fails to consider what might be meaningful differences between equally accurate models with respect to other criteria such as fairness, robustness, and interpretability. Unless these criteria are taken into account explicitly, developers might end up making unnecessary trade-offs or could even mask intentional discrimination. Furthermore, the prospect that there might exist another model of equal accuracy that flips a prediction for a particular individual may lead to a crisis in justifiability: why should an individual be subject to an adverse model outcome if there exists an equally accurate model that treats them more favorably? In this work, we investigate how to take advantage of the flexibility afforded by model multiplicity while addressing the concerns with justifiability that it might raise.
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If some Rashomon models predict positive and others negative for an individual, this provides a meaningful basis for contesting the decision.
“If some predictions are positive while others are negative, this provides a meaningful basis for contesting the decision, as argued by Black, Raghavan, and Barocas (2022) and formalized in the following theorem.”
From Explainable AI Isn't Enough! Rethinking Algorithmic Contestability (2026) · cites this paper as Black, Raghavan, and Barocas 2022
Non-epistemic values, such as fairness or interpretability concerns, can guide model selection in such situations.
“Indeed, non-epistemic values(Longino 2025), such as fairness or interpretability concerns, can guide model selection in such situations, an idea now widely discussed in the model multiplicity literature(Black, Raghavan, and Barocas 2022;Xin et al. 2022;Rudin et al. 2024;Meyer et al. 2025;Höltgen and Oliver 2025).”
From Explainable AI Isn't Enough! Rethinking Algorithmic Contestability (2026) · cites this paper as Black, Raghavan, and Barocas 2022
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Explainable AI Isn't Enough! Rethinking Algorithmic Contestability
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- Authors
- Black, E., Raghavan, M., & Barocas, S.
- Affiliations
- Carnegie Mellon University (US)
- Harvard University (US)
- Microsoft (United States) (US)
- Venue
- 2022 ACM Conference on Fairness Accountability and Transparency
- Publisher
- ACM
- Published
- 2022-06-20
- Pages
- 850-863
- OpenAlex
- W4283169532
- Cited by
- 85
- References
- 5
- Citations by year
- 2026: 23 · 2025: 24 · 2024: 26 · 2023: 10 · 2022: 1 · 2021: 1
- FWCI
- 13.94
- Type
- conference paper
- Language
- en
- Open access
- hybrid
- doi.org
- Licence
- Locations
- ACM Conference on Fairness, Accountability, and Transparency (FAccT) (publishedVersion, cc-by-sa)
- SSRN Electronic Journal (acceptedVersion)
- Funders
- Harvard School of Engineering and Applied Sciences
- Amazon Graduate Research Fellowship
- Microsoft Research
- Topics
- Social Sciences › Safety Research › Ethics and Social Impacts of AI
- Physical Sciences › Computer Science › Artificial Intelligence › Explainable Artificial Intelligence (XAI)
- Physical Sciences › Computer Science › Artificial Intelligence › Machine Learning and Data Classification
- Keywords
- model multiplicity, model selection, fairness, robustness, interpretability, justifiability, personalized prediction, algorithmic discrimination
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