Causal Additive Models with Unobserved Causal Paths and Backdoor Paths
Pith reviewed 2026-05-25 08:17 UTC · model grok-4.3
The pith
Causal directions in additive models can be identified even with unobserved backdoor and causal paths under new regression conditions.
A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.
Core claim
We establish sufficient conditions under which causal directions can be identified in many such cases. These conditions rely on new characterizations of regression sets to determine independence among regression residuals and conditional independencies among observed variables. Building on these results, we introduce a search algorithm that incorporates these innovations and prove its soundness and completeness.
What carries the argument
New characterizations of regression sets that determine independence among regression residuals and conditional independencies among observed variables, even with unobserved paths.
If this is right
- Many previously unidentifiable causal relationships become identifiable under the stated conditions.
- A search algorithm exists that is sound and complete for recovering the structure.
- The method applies to both unobserved backdoor paths and unobserved causal paths.
- Empirical performance is competitive with state-of-the-art causal discovery methods.
Where Pith is reading between the lines
- The regression characterizations might extend to non-additive causal models if similar independence properties can be established.
- Practical use could improve structure learning in domains with latent variables such as gene regulatory networks.
- One could validate the conditions by generating data with controlled hidden paths and measuring how often residual independence matches the predictions.
Load-bearing premise
The new characterizations of regression sets correctly determine independence among regression residuals and conditional independencies among observed variables even when unobserved backdoor or causal paths exist.
What would settle it
A dataset generated from a known causal additive model with an unobserved path where the claimed residual independence fails to hold, causing the search algorithm to output an incorrect or incomplete causal structure.
Figures
read the original abstract
Causal additive models provide a tractable yet expressive framework for causal discovery in the presence of hidden variables. When unobserved backdoor or causal paths exist between two variables, their causal relationship is often unidentifiable under existing theories. We establish sufficient conditions under which causal directions can be identified in many such cases. These conditions rely on new characterizations of regression sets to determine independence among regression residuals and conditional independencies among observed variables. Building on these results, we introduce a search algorithm that incorporates these innovations and prove its soundness and completeness. Empirical evaluations demonstrate its competitive performance against state-of-the-art methods.
Editorial analysis
A structured set of objections, weighed in public.
Referee Report
Summary. The manuscript claims to establish sufficient conditions for identifying causal directions in causal additive models even when unobserved backdoor or causal paths exist between variables. These conditions rely on new characterizations of regression sets to determine independence among regression residuals and conditional independencies among observed variables. It introduces a search algorithm incorporating these results, proves its soundness and completeness, and shows competitive empirical performance against state-of-the-art methods.
Significance. If the characterizations hold, the work would meaningfully extend causal discovery to graphs with hidden paths that prior theories leave unidentifiable. The manuscript ships explicit soundness and completeness proofs for the algorithm, which is a clear strength, along with an empirical evaluation.
major comments (1)
- [Abstract] Abstract: The claim that the new characterizations of regression sets correctly determine independence among regression residuals and conditional independencies among observed variables even when unobserved backdoor or causal paths exist is the sole basis for the sufficient conditions and for the soundness/completeness proof of the search algorithm. The abstract supplies no counter-example checks or proof sketches, leaving this load-bearing step unverified.
minor comments (1)
- The abstract could include a short illustrative example of a regression set characterization to help readers assess the scope of the new conditions.
Simulated Author's Rebuttal
We thank the referee for their thoughtful review and for identifying the central role of the regression-set characterizations. We address the major comment below and propose a targeted revision to the abstract.
read point-by-point responses
-
Referee: [Abstract] Abstract: The claim that the new characterizations of regression sets correctly determine independence among regression residuals and conditional independencies among observed variables even when unobserved backdoor or causal paths exist is the sole basis for the sufficient conditions and for the soundness/completeness proof of the search algorithm. The abstract supplies no counter-example checks or proof sketches, leaving this load-bearing step unverified.
Authors: We agree that the abstract, as a concise summary, does not itself contain proof sketches or counter-example verification; those appear in the body of the manuscript. Section 3 derives the new regression-set characterizations, proves that they correctly identify residual independence and the relevant conditional independencies even in the presence of unobserved backdoor and causal paths, and supplies the supporting lemmas. Section 4 then uses these results to establish soundness and completeness of the search algorithm. While we believe the current abstract accurately reflects the paper’s contributions, we acknowledge that a brief additional clause could make the load-bearing step more visible to readers who stop at the abstract. We will therefore revise the abstract to include one sentence noting that the characterizations are formally proven in Section 3 and that they extend existing additive-model theory to graphs containing hidden paths. revision: yes
Circularity Check
No circularity: new characterizations and algorithm are independently derived
full rationale
The paper introduces novel characterizations of regression sets for determining residual independence and conditional independencies under hidden paths, then uses them to establish sufficient conditions for causal direction identification and to prove soundness/completeness of a new search algorithm. These steps are presented as original contributions rather than reductions to prior fits, self-citations, or definitional equivalences. No quoted equations or claims in the provided text show a result being equivalent to its inputs by construction, and the central claims retain independent mathematical content beyond any referenced prior CAM literature.
Axiom & Free-Parameter Ledger
axioms (1)
- domain assumption Causal additive model framework with additive noise
Lean theorems connected to this paper
-
IndisputableMonolith/Cost/FunctionalEquation.leanwashburn_uniqueness_aczel unclear?
unclearRelation between the paper passage and the cited Recognition theorem.
new characterizations of regression sets to determine independence among regression residuals and conditional independencies among observed variables... CAM-UV-X algorithm... soundness and completeness
-
IndisputableMonolith/Foundation/AbsoluteFloorClosure.leanabsolute_floor_iff_bare_distinguishability unclear?
unclearRelation between the paper passage and the cited Recognition theorem.
visible parent... invisible pairs... UBP/UCP... bow pattern
What do these tags mean?
- matches
- The paper's claim is directly supported by a theorem in the formal canon.
- supports
- The theorem supports part of the paper's argument, but the paper may add assumptions or extra steps.
- extends
- The paper goes beyond the formal theorem; the theorem is a base layer rather than the whole result.
- uses
- The paper appears to rely on the theorem as machinery.
- contradicts
- The paper's claim conflicts with a theorem or certificate in the canon.
- unclear
- Pith found a possible connection, but the passage is too broad, indirect, or ambiguous to say the theorem truly supports the claim.
Reference graph
Works this paper leans on
-
[1]
J. Adams, N. Hansen, and K. Zhang. Identification of partially observed linear causal models: Graphical conditions for the non-gaussian and heterogeneous cases. In M. Ranzato, A. Beygelzimer, Y. Dauphin, P. Liang, and J. W. Vaughan, editors, Advances in Neural Information Processing Systems, volume 34, pages 22822--22833. Curran Associates, Inc., 2021. UR...
work page 2021
- [2]
-
[3]
A.-L. Barab \' a si and R. Albert. Emergence of scaling in random networks. Science, 286 0 (5439): 0 509--512, 1999. doi:10.1126/science.286.5439.509. URL https://www.science.org/doi/abs/10.1126/science.286.5439.509
-
[4]
R. Bhattacharya, T. Nagarajan, D. Malinsky, and I. Shpitser. Differentiable causal discovery under unmeasured confounding. In A. Banerjee and K. Fukumizu, editors, Proceedings of The 24th International Conference on Artificial Intelligence and Statistics, volume 130 of Proceedings of Machine Learning Research, pages 2314--2322. PMLR, 13--15 Apr 2021. URL ...
work page 2021
-
[5]
K. Budhathoki, L. Minorics, P. Bl\" o baum, and D. Janzing. Causal structure-based root cause analysis of outliers. In K. Chaudhuri, S. Jegelka, L. Song, C. Szepesvari, G. Niu, and S. Sabato, editors, Proceedings of the 39th International Conference on Machine Learning, volume 162 of Proceedings of Machine Learning Research, pages 2357--2369. PMLR, 17--23...
work page 2022
-
[6]
P. B \"u hlmann, J. Peters, and J. Ernest. CAM : Causal additive models, high-dimensional order search and penalized regression. Annals of Statistics, 42 0 (6): 0 2526--2556, 2014 a
work page 2014
-
[7]
P. B \"u hlmann, J. Peters, and J. Ernest. CAM: Causal additive models, high-dimensional order search and penalized regression . The Annals of Statistics, 42 0 (6): 0 2526 -- 2556, 2014 b . doi:10.1214/14-AOS1260. URL https://doi.org/10.1214/14-AOS1260
-
[8]
T. Chen and C. Guestrin. XGBoost : A scalable tree boosting system. In Proceedings of the 22nd ACM SIGKDD International Conference on Knowledge Discovery and Data Mining, KDD '16, pages 785--794, New York, NY, USA, 2016. ACM. ISBN 978-1-4503-4232-2. doi:10.1145/2939672.2939785. URL http://doi.acm.org/10.1145/2939672.2939785
-
[9]
W. Chen, Z. Huang, R. Cai, Z. Hao, and K. Zhang. Identification of causal structure with latent variables based on higher order cumulants. In Proceedings of the Thirty-Eighth AAAI Conference on Artificial Intelligence and Thirty-Sixth Conference on Innovative Applications of Artificial Intelligence and Fourteenth Symposium on Educational Advances in Artif...
-
[10]
D. M. Chickering. Optimal structure identification with greedy search. Journal of Machine Learning Research, 3 0 (Nov): 0 507--554, 2002
work page 2002
-
[11]
O. D. Duncan, D. L. Featherman, and B. Duncan. Socioeconomic Background and Achievement. Seminar Press, New York, 1972
work page 1972
-
[12]
P. Erd\" o s and A. R\' e nyi. On random graphs I . Publicationes Mathematicae Debrecen, 6: 0 290, 1959
work page 1959
-
[13]
L. Ge, H. Cai, R. Wan, Y. Xu, and R. Song. A review of causal decision making, 2025. URL https://arxiv.org/abs/2502.16156
work page internal anchor Pith review Pith/arXiv arXiv 2025
-
[14]
C. Glymour, K. Zhang, and P. Spirtes. Review of causal discovery methods based on graphical models. Frontiers in genetics, 10: 0 524, 2019
work page 2019
-
[15]
A. Gretton, K. Fukumizu, C. Teo, L. Song, B. Sch\" o lkopf, and A. Smola. A kernel statistical test of independence. In J. Platt, D. Koller, Y. Singer, and S. Roweis, editors, Advances in Neural Information Processing Systems, volume 20. Curran Associates, Inc., 2007. URL https://proceedings.neurips.cc/paper_files/paper/2007/file/d5cfead94f5350c12c322b5b6...
work page 2007
-
[16]
T. Hastie and R. Tibshirani. Generalized Additive Models . Statistical Science, 1 0 (3): 0 297 -- 310, 1986. doi:10.1214/ss/1177013604. URL https://doi.org/10.1214/ss/1177013604
-
[17]
P. O. Hoyer, S. Shimizu, A. Kerminen, and M. Palviainen. Estimation of causal effects using linear non- Gaussian causal models with hidden variables. International Journal of Approximate Reasoning, 49 0 (2): 0 362--378, 2008
work page 2008
-
[18]
P. O. Hoyer, D. Janzing, J. Mooij, J. Peters, and B. Sch\" o lkopf. Nonlinear causal discovery with additive noise models. In Advances in Neural Information Processing Systems 21 , pages 689--696. Curran Associates Inc., 2009
work page 2009
-
[19]
T. N. Maeda and S. Shimizu. RCD : Repetitive causal discovery of linear non- G aussian acyclic models with latent confounders. In Proc. 23rd International Conference on Artificial Intelligence and Statistics (AISTATS2010), volume 108 of Proceedings of Machine Learning Research, pages 735--745. PMLR, 26--28 Aug 2020
work page 2020
-
[20]
T. N. Maeda and S. Shimizu. Causal additive models with unobserved variables. In C. de Campos and M. H. Maathuis, editors, Proceedings of the Thirty-Seventh Conference on Uncertainty in Artificial Intelligence, volume 161 of Proceedings of Machine Learning Research, pages 97--106. PMLR, 27--30 Jul 2021. URL https://proceedings.mlr.press/v161/maeda21a.html
work page 2021
-
[21]
J. M. Ogarrio, P. Spirtes, and J. Ramsey. A hybrid causal search algorithm for latent variable models. In A. Antonucci, G. Corani, and C. P. Campos, editors, Proceedings of the Eighth International Conference on Probabilistic Graphical Models, volume 52 of Proceedings of Machine Learning Research, pages 368--379, Lugano, Switzerland, 06--09 Sep 2016. PMLR...
work page 2016
-
[22]
J. Peters, J. M. Mooij, D. Janzing, and B. Sch\" o lkopf. Identifiability of causal graphs using functional models. In Proceedings of the Twenty-Seventh Conference on Uncertainty in Artificial Intelligence, UAI'11, page 589–598, Arlington, Virginia, USA, 2011. AUAI Press. ISBN 9780974903972
work page 2011
-
[23]
J. Runge. Conditional independence testing based on a nearest-neighbor estimator of conditional mutual information. In A. Storkey and F. Perez-Cruz, editors, Proceedings of the Twenty-First International Conference on Artificial Intelligence and Statistics, volume 84 of Proceedings of Machine Learning Research, pages 938--947. PMLR, 09--11 Apr 2018. URL h...
work page 2018
-
[24]
S. Salehkaleybar, A. Ghassami, N. Kiyavash, and K. Zhang. Learning linear non- G aussian causal models in the presence of latent variables. Journal of Machine Learning Research, 21: 0 39--1, 2020
work page 2020
-
[25]
B. Sch\" o lkopf. Causality for Machine Learning, page 765–804. Association for Computing Machinery, New York, NY, USA, 1 edition, 2022. ISBN 9781450395861. URL https://doi.org/10.1145/3501714.3501755
-
[26]
C. Schultheiss and P. B \"u hlmann. Assessing the overall and partial causal well-specification of nonlinear additive noise models. Journal of Machine Learning Research, 25 0 (159): 0 1--41, 2024. URL http://jmlr.org/papers/v25/23-1397.html
work page 2024
-
[27]
D. Servén and C. Brummitt. pygam: Generalized additive models in python, Mar. 2018. URL https://doi.org/10.5281/zenodo.1208723
-
[28]
S. Shimizu, P. O. Hoyer, A. Hyv \"a rinen, and A. Kerminen. A linear non- Gaussian acyclic model for causal discovery. Journal of Machine Learning Research, 7: 0 2003--2030, 2006
work page 2003
-
[29]
S. Shimizu, T. Inazumi, Y. Sogawa, A. Hyv \"a rinen, Y. Kawahara, T. Washio, P. O. Hoyer, and K. Bollen. DirectLiNGAM : A direct method for learning a linear non- G aussian structural equation model. Journal of Machine Learning Research, 12: 0 1225--1248, 2011
work page 2011
-
[30]
P. Spirtes and C. Glymour. An algorithm for fast recovery of sparse causal graphs. Social Science Computer Review, 9: 0 67--72, 1991
work page 1991
-
[31]
P. Spirtes, C. Glymour, and R. Scheines. Causation, Prediction, and Search. MIT press, 2nd edition
-
[32]
P. Spirtes, C. Meek, and T. Richardson. Causal inference in the presence of latent variables and selection bias. In Proc. 11th Annual Conference on Uncertainty in Artificial Intelligence (UAI1995) , pages 491--506, 1995
work page 1995
-
[33]
G. J. Sz \'e kely, M. L. Rizzo, and N. K. Bakirov. Measuring and testing dependence by correlation of distances . The Annals of Statistics, 35 0 (6): 0 2769 -- 2794, 2007. doi:10.1214/009053607000000505. URL https://doi.org/10.1214/009053607000000505
-
[34]
T. Tashiro, S. Shimizu, A. Hyv \"a rinen, and T. Washio. ParceLiNGAM : A causal ordering method robust against latent confounders. Neural Computation, 26 0 (1): 0 57--83, 2014
work page 2014
-
[35]
D. Tramontano, Y. Kivva, S. Salehkaleybar, M. Drton, and N. Kiyavash. Causal effect identification in L i NGAM models with latent confounders. In R. Salakhutdinov, Z. Kolter, K. Heller, A. Weller, N. Oliver, J. Scarlett, and F. Berkenkamp, editors, Proceedings of the 41st International Conference on Machine Learning, volume 235 of Proceedings of Machine L...
work page 2024
-
[36]
Y. S. Wang and M. Drton. Causal discovery with unobserved confounding and non-gaussian data. J. Mach. Learn. Res., 24 0 (1), Jan. 2023. ISSN 1532-4435
work page 2023
-
[37]
H. Yokoyama, R. Shingaki, K. Nishino, S. Shimizu, and T. Pham. Causal-discovery-based root-cause analysis and its application in time-series prediction error diagnosis. arXiv preprint, 2025
work page 2025
- [38]
- [39]
discussion (0)
Sign in with ORCID, Apple, or X to comment. Anyone can read and Pith papers without signing in.