Transparent Intelligence Publishing Transparent Intelligence Publishing

Making Machine Reasoning Open to Question: An Integrative Review of Causal, Neuro-Symbolic, Knowledge-Grounded, and Uncertainty-Aware Explainability

Review | Open access | Published: 15 March 2026
Volume 5, article number 83, (2026) Cite this article
You have full access to this open access article.
Download PDF
, ,
  1. Department of AI and Reasoning Systems, University of Lisbon, Lisbon, Portugal
  2. Department of Computer Science, Sultan Qaboos University, Muscat, Oman
  3. Department of Information Technology, University of Milan, Milan, Italy
117 Accesses

Abstract

Explainable artificial intelligence increasingly seeks to provide more than visualisations of feature importance or simplified descriptions of model outputs. For intelligent systems used in consequential settings, machine reasoning should be open to questioning, inspection, contextualisation, correction, and evaluation under uncertainty. This integrative review examines emerging approaches that may support this broader objective. It connects causal explainability and counterfactual reasoning with neuro-symbolic intelligence, knowledge-grounded inference, uncertainty-aware explanation, reliability evaluation, and human-centred interpretability. The review uses a structured integrative approach to compare how these paradigms represent causes, alternatives, rules, concepts, knowledge sources, inferential steps, confidence, and limitations. Causal and counterfactual approaches can support questions about mechanisms, contrasts, interventions, actionability, and recourse, but their conclusions depend on explicit assumptions, feasible alternatives, and appropriate causal evidence. Neuro-symbolic and knowledge-grounded approaches can make concepts, relations, rules, provenance, and intermediate reasoning more traceable, although symbolic structure or retrieved knowledge does not automatically ensure faithful, valid, or truthful explanation. Uncertainty-aware approaches can qualify predictions and explanations through uncertainty characterisation, calibration, confidence communication, robustness assessment, and human interpretation, but uncertainty estimates alone do not establish reliability. The synthesis indicates that no individual paradigm is sufficient. More defensible machine reasoning requires complementary evaluation of explanation fidelity, causal plausibility, knowledge validity, reasoning traceability, uncertainty communication, cognitive accessibility, contestability, and lifecycle accountability. Important research opportunities concern causal validation, feasible recourse, provenance governance, explanation uncertainty, hybrid-system evaluation, human-centred testing, and cross-paradigm assessment. The review contributes an integrated account of how machine reasoning may become not merely visible, but meaningfully open to question.

Explore related subjects
Discover the latest articles in related subjects:

Introduction

Explainable artificial intelligence has developed into a broad field encompassing interpretable modelling, post-hoc explanation, local and global analysis, visualisation, rule extraction, example-based explanation, and responsible-AI considerations. These approaches differ in what they expose, whom they address, and whether they aim to describe model behaviour, support understanding, enable oversight, or justify decisions. Consequently, explanation availability cannot be treated as a uniform property or as sufficient evidence that an intelligent system is trustworthy [1].

Many widely used explanation techniques illuminate correlations between inputs and outputs without revealing a complete inferential process. Feature attribution, surrogate modelling, decision rules, prototypes, and counterfactual examples may provide valuable access to model behaviour, yet each represents only a particular explanatory perspective. A system may therefore be locally explainable while its knowledge sources, causal assumptions, uncertainty, internal dependencies, or decision boundaries remain difficult to inspect [2].

Human explanation also differs from unrestricted technical disclosure. People commonly seek selective and contrastive answers: why one outcome occurred rather than another, what information mattered, what alternatives were possible, and how a decision could be challenged or changed. Explanations are consequently shaped by the recipient’s question, prior knowledge, practical objective, and social context. Machine reasoning becomes meaningfully open to question only when explanatory information supports such situated inquiry [3].

This review integrates emerging approaches that move beyond surface-level visibility toward reasoning that can be interrogated, contextualised, qualified, and criticised. Its central contribution is to connect causal, counterfactual, neuro-symbolic, knowledge-grounded, and uncertainty-aware explainability through shared concerns about reasoning transparency, explanation fidelity, traceability, human critique, and reliability. The synthesis remains evaluative rather than prescriptive: explanation design must be aligned with the intended domain, users, decisions, and validation requirements before it can contribute to trustworthy practice [4].

Emerging Paradigms for Reliable Machine Reasoning

Established explainability research provides an essential foundation for reasoning-oriented approaches. Model-specific and model-agnostic methods can describe global behaviour, individual predictions, feature influence, decision boundaries, representative cases, and extracted rules. Emerging paradigms should therefore not be understood as replacements for conventional explainability. Rather, they expand the object of explanation from predictive behaviour toward mechanisms, alternatives, structured knowledge, inferential relations, and limitations [5].

Deep-learning explanations illustrate why this expansion is necessary. Attribution maps, relevance propagation, activation analysis, concept methods, and visualisation techniques can reveal how neural models respond to particular inputs. Nevertheless, sensitivity to a feature does not demonstrate that the feature constitutes a causal reason, that the explanation reproduces the complete decision process, or that the same rationale remains stable under meaningful changes. Reasoning transparency requires additional evidentiary and structural support [6].

Reliable machine reasoning also raises a design-level question: whether an opaque model should be explained after prediction or replaced by an interpretable model when a sufficiently accurate transparent alternative is available. In high-stakes contexts, post-hoc explanation can introduce approximation errors and may provide an appearance of understanding without exposing the actual decision logic. Interpretability, explanation fidelity, and model selection must therefore be considered together rather than treated as interchangeable remedies for opacity [7].

Causal explanation, counterfactual questioning, neuro-symbolic reasoning, knowledge grounding, and uncertainty communication represent complementary responses to these limitations. They seek to expose mechanisms, possible alternatives, symbolic relationships, evidence sources, inferential steps, or limits on confidence. However, none automatically establishes dependable reasoning. Their contribution depends on validated assumptions, faithful traces, reliable knowledge, comprehensible communication, and opportunities for human challenge, correction, and oversight [8].

Review Scope and Integrative Analytical Approach

The review addresses six integrative questions: how emerging paradigms make reasoning open to question; how causal and counterfactual approaches support explanation, action, and critique; how neuro-symbolic and knowledge-grounded approaches support traceability; how uncertainty-aware explanation contributes to reliable interpretation; where these approaches can converge; and which research gaps prevent accountable use. Evaluation is treated as multidimensional because existing XAI assessment remains fragmented across fidelity, robustness, plausibility, usefulness, stability, and human-centred criteria [9].

The analytical scope includes peer-reviewed journal scholarship relevant to explainable machine reasoning, causal explanation, counterfactual reasoning, neuro-symbolic intelligence, structured knowledge, uncertainty communication, and trustworthy AI. Sources were retained when they supplied conceptual distinctions, methodological comparisons, human-centred findings, evaluation principles, or integrative implications. Narrow performance studies without a clear reasoning, explanation, reliability, or accountability contribution were excluded. This approach distinguishes explanation objectives and evaluation targets rather than assuming that interpretability has a single accepted meaning [10].

Evidence extraction focused on the reasoning question addressed, the explanatory function performed, the relevant assumptions, the potential human use, the major failure or overclaiming risk, and the required validation or governance process. The synthesis also distinguished fidelity from plausibility, explanation from justification, causal reasoning from associative prediction, structured knowledge from validated knowledge, and confidence from demonstrated reliability. These distinctions reflect the pragmatic principle that explanatory value depends partly on the user’s epistemic situation and practical purpose [11].

The synthesis proceeded through cross-paradigm comparison rather than quantitative aggregation. Each approach was examined according to what can be questioned: model behaviour, causal assumptions, alternatives, rules, semantic relations, knowledge sources, inferential steps, uncertainty, or institutional responsibility. Human–agent explainability was therefore treated as an interaction involving an identifiable recipient, task, timing, and decision context rather than as static information presented independently of use [12].

Table 1 summarises the integrative review logic used to connect causal, neuro-symbolic, knowledge-grounded, and uncertainty-aware explainability as emerging paradigms for reliable machine reasoning.

Table 1. Integrative Review Logic for Reliable Machine Reasoning: Review Questions, Analytical Scope, Inclusion Criteria, Exclusion Criteria, Evidence Extraction Categories, Paradigm Mapping, Reasoning-Transparency Dimensions, Citation Planning, and Review Boundaries

Review component

Core integrative question or purpose

Inclusion logic

Exclusion logic

Evidence mapped

Reasoning or explainability dimension addressed

Bias or limitation risk

Integrative review role

Problem framing

What makes machine reasoning open to question?

Work addressing explanation, reasoning, reliability, or critique

Work limited to predictive accuracy

Definitions and conceptual boundaries

Reasoning transparency and human critique

Overly broad use of “explanation”

Establishes the review’s central problem

Causal stream

How are causes, interventions, and assumptions represented?

Causal explanation, inference, graphs, pathways, and interventions

Associational interpretation presented as causality

Causal claims, assumptions, and validation needs

Causal plausibility and intervention reasoning

Causal overclaiming

Defines causal-questioning boundaries

Counterfactual stream

How are alternatives, actionability, and recourse addressed?

Contrastive, counterfactual, what-if, and recourse research

Alternatives lacking explanatory relevance

Feasibility, proximity, actionability, and consequences

Alternative-based explanation

Unrealistic or ineffective alternatives

Separates explanation from guaranteed recourse

Neuro-symbolic stream

How are learned and structured reasoning integrated?

Hybrid, symbolic, relational, compositional, and logic-based reasoning

Architecture descriptions without explanatory relevance

Integration points and reasoning traces

Structured reasoning and traceability

Assuming symbols ensure interpretability

Compares hybrid reasoning functions

Knowledge-grounded stream

What knowledge supports the inference?

Knowledge graphs, ontologies, grounding, provenance, and validity

Retrieval without reasoning or explanation relevance

Source lineage, semantic relations, and knowledge quality

Knowledge traceability

Treating retrieval as factual proof

Connects evidence sources with critique

Uncertainty stream

How are limitations and confidence communicated?

UQ, calibration, confidence, robustness, and uncertainty communication

Confidence values without reliability relevance

Uncertainty type, estimation, and interpretation

Qualified explanation and reliability

Miscalibration or user misunderstanding

Integrates uncertainty with explanation

Human-centred stream

Who questions the reasoning and for what purpose?

Human understanding, interaction, contestability, and trust calibration

Explanation evaluated only through technical availability

Audience, task, usefulness, and cognitive demands

Cognitive accessibility

Generalising across stakeholder groups

Connects technical explanations with use

Synthesis and boundaries

Where can approaches converge without overclaiming?

Evidence supporting complementary functions or identified gaps

Claims of universal sufficiency or readiness

Trade-offs, convergence opportunities, and research needs

Cross-cutting accountability

Normative inference beyond evidence

Produces the integrative contribution

Figure 1 illustrates the integrative analytical approach used to connect causal, counterfactual, neuro-symbolic, knowledge-grounded, and uncertainty-aware explainability as complementary routes toward machine reasoning that can be questioned.

Figure 1. Integrative Analytical Map for Questionable Machine Reasoning

Figure 1. Integrative Analytical Map for Questionable Machine Reasoning

Alt-text description:

An integrative review map showing causal explainability, counterfactual reasoning, neuro-symbolic intelligence, knowledge grounding, uncertainty-aware explanations, reliability, human critique, accountability, synthesis, and future research gaps.

Causal Explainability and Counterfactual Reasoning

Causal explainability seeks to move from statistical association toward accounts of variables, mechanisms, and interventions that may influence an outcome. Causal reasoning asks what would occur if a condition were actively changed, whereas causal inference concerns whether such effects can be identified from data under stated assumptions. Causal representation learning may support mechanism-sensitive reasoning and robustness across changing environments, but its conclusions remain dependent on identifiability, invariance, data adequacy, and domain knowledge [13].

A causal explanation should therefore make its assumptions open to challenge. It may refer to a causal graph, pathway, mediator, intervention, or structural relationship, but the presence of causal terminology does not prove that the represented relation is correct. Counterfactual explanation can strengthen questioning by showing how an alternative state relates to a different outcome, yet a generated alternative can remain associational, infeasible, or inconsistent with the underlying data-generating process [14].

Counterfactual methods commonly optimise several competing properties, including proximity to the observed case, sparsity of change, plausibility, diversity, stability, and actionability. Improvements in one property may weaken another. A very close counterfactual can depend on an immutable characteristic, while a plausible alternative can require several costly changes. Counterfactual quality must consequently be evaluated against the intended explanatory and decision context rather than through a single generic criterion [15].

Contrastive explanation addresses why one outcome occurred rather than a specified alternative, while what-if reasoning explores how predictions respond to hypothetical changes. These approaches can be cognitively useful because they correspond to common human questions, but they should not be conflated with intervention-based causal reasoning. Their validity depends on meaningful foil selection, realistic feature dependencies, temporal order, and an explicit distinction between model sensitivity and changes that would occur in the world [16].

Actionability concerns whether a proposed change can be performed, whereas recourse asks whether feasible action is likely to produce a favourable future result. A nearby counterfactual does not guarantee either. Recommendations may fail because of causal dependencies, institutional constraints, model updates, delayed effects, or environmental uncertainty. Responsible recourse therefore requires feasibility assessment, causal and consequential validation, monitoring, and an accountable process through which affected people can question ineffective recommendations [17].

Table 2 maps causal explainability and counterfactual reasoning approaches according to reasoning questions, explanation functions, assumptions, validation needs, accountability roles, and boundary conditions.

Table 2. Causal Explainability and Counterfactual Reasoning for Questionable Machine Reasoning: Causal Explanation, Counterfactual Explanation, Contrastive Explanation, What-If Reasoning, Intervention Reasoning, Actionability, Recourse, Causal Graphs, Causal Assumptions, Feasibility Constraints, and Causal-Truth Boundaries

Approach or concept

Core reasoning question

Explanation function

Potential use

Failure or overclaiming risk

Validation or assumption need

Human critique or accountability role

Integrative review role

Causal explainability

Which mechanisms are claimed to produce the outcome?

Connects explanation with causal structure

Mechanism-oriented interpretation

Association may be presented as causation

Explicit model, assumptions, and domain evidence

Enables challenges to the proposed mechanism

Extends explanation beyond sensitivity

Causal inference

What causal effect is identifiable?

Estimates effects under assumptions

Intervention and policy comparison

Confounding or misspecification

Identification strategy and sensitivity analysis

Exposes evidentiary premises

Disciplines causal claims

Causal explanation

What caused this outcome under the stated account?

Gives an outcome-specific causal justification

Decision and incident review

May imply excessive certainty

Causal definition, contrast, and evidence

Supports dispute over causes

Adds mechanism-sensitive critique

Counterfactual reasoning

What would happen under an alternative condition?

Compares actual and alternative states

Scenario exploration

Alternative world may be incoherent

Structural dependencies and temporal validity

Tests hidden dependencies

Supports alternative-based questioning

Counterfactual explanation

What must differ for the output to change?

Produces an output-changing alternative

Local explanation

Minimal change may be infeasible

Plausibility, stability, and causal consistency

Provides a concrete basis for challenge

Links explanation and possible action

Contrastive explanation

Why this outcome rather than the foil?

Selects differences relevant to a comparison

Human-centred explanation

Misleading foil selection

Explicit and meaningful comparison

Lets users define the relevant alternative

Aligns explanation with user questions

What-if reasoning

How does the model respond to hypothetical variation?

Reveals prediction sensitivity

Interactive exploration

Hypothetical values may violate dependencies

Realistic ranges and constraints

Supports probing of model behaviour

Offers exploration without causal proof

Intervention reasoning

What follows from actively changing a variable?

Represents action within a causal system

Planning and decision support

Downstream effects may be omitted

Valid intervention semantics

Enables scrutiny of recommended actions

Bridges causal explanation and action

Actionability and feasibility

Can the proposed change realistically be made?

Filters alternatives by controllability

Practical guidance

Social or institutional barriers may be ignored

User- and context-specific constraints

Prevents impossible burdens being shifted to users

Grounds counterfactuals in real conditions

Recourse

Will feasible action improve a future decision?

Converts explanation into consequential guidance

Response to adverse decisions

Outcome improvement may not persist

Prospective validation and institutional support

Supports remedy and appeal

Separates explanation from guaranteed benefit

Causal graphs and pathways

Which variables, edges, and mediators structure the account?

Makes relationships inspectable

Process analysis

Graphs may be incomplete or disputed

Structure validation and expert review

Allows challenges to nodes, edges, and omissions

Supplies a traceable causal representation

Causal assumptions

Which premises must hold?

Makes causal conditions explicit

Audit and sensitivity analysis

Hidden assumptions create false authority

Documentation and stress testing

Provides specific propositions to contest

Central condition of questionable reasoning

No causal-truth or recourse guarantee

What cannot be concluded from the explanation alone?

Defines interpretive boundaries

Responsible communication

Explanation may be mistaken for proof or remedy

Independent evidence and monitoring

Protects users from overclaiming

Preserves the review’s sufficiency boundaries

Neuro-Symbolic Intelligence and Knowledge-Grounded Inference

Neuro-symbolic intelligence combines statistical learning with structured representations or inference. Its architectures may connect neural perception with relational learning, constraints, rules, logic, or symbolic outputs. Because these combinations differ substantially, neuro-symbolic AI should be treated as a family of hybrid approaches rather than a single reasoning model. Its explanatory value depends on which component is exposed and whether the resulting trace corresponds faithfully to the system’s operation [18].

The prospect of combining adaptive learning with explicit reasoning has motivated descriptions of neuro-symbolic AI as a further wave of intelligent-system research. Symbols, concepts, and rules may make some intermediate operations easier to inspect, but their presence does not make an entire system interpretable. Neural representations, interfaces between components, and conflict-resolution mechanisms can remain opaque and require independent evaluation [19].

Neuro-symbolic designs also differ according to where structured knowledge enters the system. Logic may constrain learning, supervise representation formation, guide inference, validate outputs, or appear only in the final explanation. Compositional and relational reasoning can potentially support reusable concepts and explicit relationships, yet systematic generalisation and trace fidelity must be demonstrated rather than inferred from architectural labels [20].

Knowledge-grounded explanation introduces identifiable domain concepts, entities, relations, or evidence into predictive reasoning. Knowledge graphs can contextualise outputs through semantic paths and structured associations, making it possible to inspect which concepts or relations supported an explanation. Their usefulness nevertheless depends on knowledge coverage, relevance, integration quality, and the extent to which graph-derived paths accurately represent the model’s reasoning [21].

Ontologies, schemas, rules, and provenance records can strengthen traceability by identifying how knowledge was represented, sourced, and transformed. However, structured knowledge may remain incomplete, outdated, disputed, or incorrectly connected to a conclusion. Knowledge grounding should therefore expose source lineage, semantic commitments, and validity limitations rather than functioning as an automatic factuality guarantee [22].

Uncertainty-Aware Explanations and Reliability

Uncertainty-aware explainability qualifies what a model or explanation claims to know. Epistemic uncertainty concerns limitations in data, knowledge, or model specification and may sometimes be reduced through additional evidence. Aleatoric uncertainty concerns variability associated with the observed process or measurement conditions. These categories are conceptually distinct, although their practical separation can depend on modelling assumptions [23].

Deep-learning uncertainty can be estimated through Bayesian approximations, ensembles, predictive distributions, evidential methods, or related techniques. These approaches differ in computational demands, assumptions, calibration behaviour, and sensitivity to unfamiliar inputs. An uncertainty estimate should consequently be interpreted as a method-dependent output requiring validation rather than as a complete representation of all possible failure [24].

Interpretability and uncertainty can provide complementary information. An explanation may indicate which evidence influenced a prediction, while uncertainty may communicate how cautiously the prediction should be treated. Presenting these signals together may support faster calibration of reliance, but the effect depends on explanation fidelity, uncertainty quality, interface design, user expertise, and decision stakes [25].

Uncertainty communication should help users decide whether to accept, question, defer, corroborate, or seek another opinion. Raw probabilities or confidence labels may be insufficient when users cannot identify what is uncertain or what response is appropriate. Human-centred assessment should therefore test comprehension and decision behaviour rather than assuming that displaying uncertainty automatically improves judgement [26].

Reliability extends beyond confidence estimation. It includes dependable performance under intended conditions, calibration, robustness, external validity, monitoring, and appropriate responses to distribution change. Uncertainty quantification can support responsible decision assistance, but it cannot independently establish that a system is accurate, safe, fair, or operationally dependable [27].

Table 3 synthesises neuro-symbolic, knowledge-grounded, and uncertainty-aware explanation approaches, including reasoning traceability, knowledge provenance, uncertainty communication, reliability, and validation needs.

Table 3. Neuro-Symbolic, Knowledge-Grounded, and Uncertainty-Aware Explainability for Reliable Machine Reasoning: Symbolic Reasoning, Sub-Symbolic Learning, Knowledge Representation, Knowledge Graphs, Ontologies, Rule-Based Inference, Reasoning Traces, Knowledge Provenance, Uncertainty Quantification, Calibration, Confidence Communication, and Reliability Boundaries

Approach or concept

Core reasoning or reliability question

Knowledge, reasoning, or uncertainty function

Potential explanation role

Failure or overclaiming risk

Validation, governance, or monitoring need

Human critique or traceability role

Integrative review role

Neuro-symbolic AI

How are learning and structured reasoning connected?

Integrates neural and symbolic components

Exposes concepts or intermediate operations

Hybridisation may be mistaken for interpretability

Component and end-to-end evaluation

Enables cross-component inspection

Connects adaptive learning with explicit structure

Symbolic and rule-based reasoning

Which premises and rules produce the conclusion?

Applies explicit logic or conditions

Produces inspectable derivations

Valid logic may use invalid premises

Rule verification and domain review

Supports rule-level contestation

Strengthens formal traceability

Sub-symbolic learning

Which statistical patterns support the output?

Learns distributed representations

Supplies predictive inputs to structured reasoning

Internal representations remain opaque

Robustness and representation testing

Requires complementary explanatory access

Provides adaptive pattern recognition

Hybrid reasoning

How are conflicting reasoning modes reconciled?

Combines statistical and structured inference

Shows complementary evidence and constraints

Interfaces may conceal failure propagation

Integration and conflict-resolution testing

Supports scrutiny of component disagreement

Enables cross-paradigm convergence

Knowledge representation and ontology

Which concepts and relations define the domain?

Encodes entities, categories, properties, and constraints

Clarifies semantic assumptions

Categories may be incomplete or contested

Ontology governance and version control

Enables challenges to definitions

Grounds reasoning in explicit semantics

Knowledge graph

Which entities and paths support the conclusion?

Organises relational knowledge

Provides contextual evidence paths

Graph structure may be inaccurate or incomplete

Quality, coverage, and relevance assessment

Supports path-level inspection

Connects explanation with structured evidence

Knowledge provenance and validity

Where did knowledge originate, and is it appropriate?

Records source and transformation history

Enables evidence attribution

A cited source may not support the inference

Source authentication and correction workflows

Supports audit and correction

Links grounding with accountability

Reasoning trace

Which steps led to the output?

Records intermediate operations

Makes inference inspectable

Generated traces may be incomplete or post-hoc

Fidelity and reproducibility testing

Provides concrete points for challenge

Operationalises reasoning traceability

Uncertainty quantification

What uncertainty can the model estimate?

Characterises predictive limitations

Qualifies conclusions

Estimates may be miscalibrated

External validation and recalibration

Supports cautious interpretation

Adds epistemic qualification

Calibration

Does expressed confidence match observed performance?

Relates probability to empirical frequency

Makes confidence more interpretable

Aggregate calibration can conceal subgroup error

Contextual and subgroup monitoring

Enables scrutiny of confidence claims

Connects confidence with reliability evidence

Confidence and uncertainty communication

How should limitations be presented to users?

Translates estimates into decision information

Supports deferral and corroboration

Displays may confuse or falsely reassure

Human-centred interface testing

Enables appropriate questioning

Connects technical uncertainty with action

Reliability and robustness

Does the system remain dependable under intended and changing conditions?

Evaluates performance and stability

Communicates operating boundaries

Explanation may substitute for reliability evidence

Lifecycle testing and shift monitoring

Supports escalation and oversight

Establishes the no-reliability-guarantee boundary

Integrative Synthesis of Emerging Approaches

An integrative account begins with stakeholder needs. Different users may seek causal understanding, actionable alternatives, evidence provenance, reasoning traces, uncertainty, or opportunities to appeal. No explanation paradigm can satisfy these requirements without specifying the recipient, decision context, explanatory objective, and property being evaluated [28].

Trustworthy machine reasoning is therefore multidimensional. Causal plausibility cannot substitute for knowledge validity, and traceability cannot substitute for reliability. Similarly, calibrated confidence does not establish fairness or accountability. Emerging approaches are most defensible when treated as complementary resources within broader responsible-AI evaluation rather than as independent proofs of trustworthiness [29].

Convergence also requires lifecycle governance. Causal assumptions, symbolic rules, knowledge sources, calibration, and explanation interfaces can become outdated as data, environments, institutions, or users change. Validation should therefore continue through monitoring, incident review, provenance management, reassessment of uncertainty, and clearly assigned responsibility for correction [30].

Human trust provides an important but insufficient evaluation outcome. Explanations may increase confidence or acceptance even when they are incomplete, persuasive, or poorly calibrated. The objective should be warranted reliance: users should know when to accept system support, when to question it, and when to seek independent evidence [31].

Perceived explainability and causability can influence trust and acceptance, but subjective approval does not establish causal truth, fidelity, or technical reliability [32]. Visibility alone also fails to create accountability when users lack authority, expertise, or institutional mechanisms for challenge and remedy [33]. Explanatory access should therefore be proportionate to decision stakes and designed to support meaningful contestability rather than exhaustive disclosure for its own sake [34].

Table 4 presents the integrative synthesis of emerging explainability approaches, including cross-paradigm tensions, convergence opportunities, remaining gaps, and future research needs.

Table 4. Integrative Synthesis of Emerging Approaches for Questionable Machine Reasoning: Causal Reasoning, Counterfactuals, Neuro-Symbolic Intelligence, Knowledge Grounding, Uncertainty-Aware Explanation, Reliability, Human Critique, Accountability, Cross-Paradigm Tensions, Convergence Opportunities, and Future Research Priorities

Synthesis theme

Approaches integrated

Core integrative question

Evidence pattern

Tension or trade-off

Convergence opportunity

Remaining gap

Integrative review contribution

Causal reasoning and uncertainty

Causal inference and UQ

How uncertain is the causal account?

Causal claims depend on assumptions

Qualification may reduce apparent simplicity

Communicate assumption-sensitive uncertainty

Limited joint evaluation protocols

Frames causality as qualified reasoning

Counterfactuals and recourse

Counterfactual explanation and actionability

When does an alternative become useful guidance?

Proximity differs from feasibility and effect

Simplicity can conflict with realism

Combine constraints, causal effects, and uncertainty

Limited prospective validation

Separates explanation from guaranteed remedy

Causal and knowledge grounding

Causal models and structured knowledge

Can knowledge expose causal premises?

Knowledge can represent mechanisms and constraints

Structured knowledge may be wrong

Link causal assumptions to validated provenance

Maintenance and consistency gaps

Makes causal premises more criticisable

Neuro-symbolic traceability

Neural, symbolic, and hybrid reasoning

Is the reasoning trace faithful?

Symbolic components can expose steps

Neural dependencies may remain opaque

Validate traces across interfaces

Limited end-to-end fidelity evidence

Treats traceability as testable

Grounding and factual reliability

Knowledge graphs and provenance

Does the cited knowledge support the conclusion?

Grounding supplies identifiable evidence

More sources may increase noise

Jointly assess source quality and entailment

Weak user-centred evidence

Separates grounding from truth

Uncertainty and trust calibration

Explanation and uncertainty communication

Does information support appropriate reliance?

Signals may be complementary

More information may overload users

Adaptive communication by role and stakes

Limited long-term studies

Prioritises calibrated reliance

Hybrid reasoning and critique

Causal, symbolic, grounded, and uncertainty-aware approaches

What can users challenge?

Structured components create critique points

Technical detail can reduce accessibility

Layered and interactive explanations

Limited human testing

Defines questionability through challenge

Evaluation across paradigms

Fidelity, plausibility, grounding, calibration, and usefulness

Which criteria are shared or paradigm-specific?

Evaluation remains fragmented

Universal metrics erase distinctions

Modular evaluation profiles

Few shared protocols

Supports comparison without universal scoring

Reliability versus complexity

Multi-component reasoning systems

Do added components justify verification burdens?

Richer systems expose more assumptions

Complexity increases maintenance needs

Measure marginal explanatory value

Limited lifecycle evidence

Frames integration as a trade-off

No single-paradigm sufficiency

All approaches

Can one paradigm establish trustworthy reasoning?

Each addresses only part of the problem

Integration creates new failure interfaces

Complementary validation and governance

Mature integrated evidence remains limited

Establishes the review’s central boundary

Research Gaps and Convergence Opportunities

Causal explanation requires stronger validation of mechanisms, assumptions, and intervention claims. Counterfactual research also needs more realistic treatment of feasibility, temporal effects, institutional constraints, and uncertainty about whether recommended actions will succeed. Future work should connect causal modelling with participatory constraint identification, sensitivity analysis, and prospective recourse evaluation rather than relying primarily on geometric proximity [13].

Neuro-symbolic and knowledge-grounded systems require scalable evaluation that separates architectural structure from demonstrated interpretability. Research should assess whether reasoning traces are faithful, whether symbolic components improve critique, whether knowledge sources support conclusions, and whether provenance permits correction. Human-centred studies are especially needed to determine whether domain experts and affected users can understand and challenge these outputs [21].

Uncertainty research should extend from prediction uncertainty to explanation uncertainty. Attributions, counterfactuals, rules, retrieved evidence, and reasoning traces may vary across methods or model states even when the prediction is stable. Joint evaluation of fidelity, stability, calibration, communication, and downstream reliance could clarify when uncertainty-aware explanation supports appropriate decisions rather than additional complexity [25].

Cross-paradigm evaluation remains fragmented. Future studies should use modular profiles combining shared criteria, such as fidelity, robustness, usefulness, and contestability, with paradigm-specific criteria for causal validity, feasible recourse, trace correspondence, knowledge provenance, and uncertainty calibration. No universal reasoning-explanation metric is likely to capture all purposes. Foundation-model applications further require cautious study of generated rationales, grounding, source use, abstention, and accountability without assuming that fluent reasoning traces are faithful.

Conclusion

This integrative review connects causal, counterfactual, neuro-symbolic, knowledge-grounded, and uncertainty-aware explainability as emerging routes toward machine reasoning that can be questioned rather than merely observed. Causal assumptions and interventions, alternative outcomes, symbolic structures, knowledge provenance, uncertainty communication, reasoning traces, and human critique provide complementary forms of explanatory access, but none is sufficient alone. Reliable machine reasoning should be assessed through fidelity, causal plausibility, feasibility, knowledge validity, calibration, robustness, cognitive accessibility, contestability, accountability, and lifecycle validation. The resulting synthesis supports disciplined integration and future research rather than a universal architecture, certification mechanism, or deployment-ready prescription.

Acknowledgements

None

Conflict of interest

None

Financial support

None

Ethics statement

None

References

Barredo Arrieta A, Díaz-Rodríguez N, Del Ser J, Bennetot A, Tabik S, Barbado A, et al. Explainable artificial intelligence (XAI): Concepts, taxonomies, opportunities and challenges toward responsible AI. Inf Fusion. 2020;58:82-115.
https://doi.org/10.1016/j.inffus.2019.12.012
Guidotti R, Monreale A, Ruggieri S, Turini F, Giannotti F, Pedreschi D. A survey of methods for explaining black box models. ACM Comput Surv. 2018;51(5):1-42.
https://doi.org/10.1145/3236009
Miller T. Explanation in artificial intelligence: Insights from the social sciences. Artif Intell. 2019;267:1-38.
https://doi.org/10.1016/j.artint.2018.07.007
Markus AF, Kors JA, Rijnbeek PR. The role of explainability in creating trustworthy artificial intelligence for health care: A comprehensive survey of the terminology, design choices, and evaluation strategies. J Biomed Inform. 2021;113:103655.
https://doi.org/10.1016/j.jbi.2020.103655
Burkart N, Huber MF. A survey on the explainability of supervised machine learning. J Artif Intell Res. 2021;70:245-317.
https://doi.org/10.1613/jair.1.12228
Samek W, Montavon G, Lapuschkin S, Anders CJ, Müller KR. Explaining deep neural networks and beyond: A review of methods and applications. Proc IEEE. 2021;109(3):247-78.
https://doi.org/10.1109/JPROC.2021.3060483
Rudin C. Stop explaining black box machine learning models for high stakes decisions and use interpretable models instead. Nat Mach Intell. 2019;1(5):206-15.
https://doi.org/10.1038/s42256-019-0048-x
Gunning D, Stefik M, Choi J, Miller T, Stumpf S, Yang GZ. XAI—Explainable artificial intelligence. Sci Robot. 2019;4(37):eaay7120.
https://doi.org/10.1126/scirobotics.aay7120
Nauta M, Trienes J, Pathak S, Nguyen E, Peters M, Schmitt Y, et al. From anecdotal evidence to quantitative evaluation methods: A systematic review on evaluating explainable AI. ACM Comput Surv. 2023;55(13s):1-42.
https://doi.org/10.1145/3583558
Vilone G, Longo L. Notions of explainability and evaluation approaches for explainable artificial intelligence. Inf Fusion. 2021;76:89-106.
https://doi.org/10.1016/j.inffus.2021.05.009
Páez A. The pragmatic turn in explainable artificial intelligence (XAI). Minds Mach. 2019;29(3):441-59.
https://doi.org/10.1007/s11023-019-09502-w
Rosenfeld A, Richardson A. Explainability in human-agent systems. Auton Agent Multi-Agent Syst. 2019;33(6):673-705.
https://doi.org/10.1007/s10458-019-09408-y
Schölkopf B, Locatello F, Bauer S, Ke NR, Kalchbrenner N, Goyal A, et al. Toward causal representation learning. Proc IEEE. 2021;109(5):612-34.
https://doi.org/10.1109/JPROC.2021.3058954
Chou YL, Moreira C, Bruza P, Ouyang C, Jorge J. Counterfactuals and causability in explainable artificial intelligence: Theory, algorithms, and applications. Inf Fusion. 2022;81:59-83.
https://doi.org/10.1016/j.inffus.2021.11.003
Guidotti R. Counterfactual explanations and how to find them: Literature review and benchmarking. Data Min Knowl Discov. 2024;38(5):2770-824.
https://doi.org/10.1007/s10618-022-00831-6
Stepin I, Alonso JM, Catalá A, Pereira-Fariña M. A survey of contrastive and counterfactual explanation generation methods for explainable artificial intelligence. IEEE Access. 2021;9:11974-2001.
https://doi.org/10.1109/ACCESS.2021.3051315
Karimi AH, Barthe G, Schölkopf B, Valera I. A survey of algorithmic recourse: Contrastive explanations and consequential recommendations. ACM Comput Surv. 2023;55(5):1-29.
https://doi.org/10.1145/3527848
Marra G, Dumančić S, Manhaeve R, De Raedt L. From statistical relational to neurosymbolic artificial intelligence: A survey. Artif Intell. 2024;328:104062.
https://doi.org/10.1016/j.artint.2023.104062
Garcez AD, Lamb LC. Neurosymbolic AI: The 3rd wave. Artif Intell Rev. 2023;56(11):12387-406.
https://doi.org/10.1007/s10462-023-10448-w
Hitzler P, Eberhart A, Ebrahimi M, Sarker MK, Zhou L. Neuro-symbolic approaches in artificial intelligence. Natl Sci Rev. 2022;9(6):nwac035.
Tiddi I, Schlobach S. Knowledge graphs as tools for explainable machine learning: A survey. Artif Intell. 2022;302:103627.
https://doi.org/10.1016/j.artint.2021.103627
Hogan A, Blomqvist E, Cochez M, d’Amato C, de Melo G, Gutierrez C, et al. Knowledge graphs. ACM Comput Surv. 2021;54(4):1-37.
https://doi.org/10.1145/3447772
Hüllermeier E, Waegeman W. Aleatoric and epistemic uncertainty in machine learning: An introduction to concepts and methods. Mach Learn. 2021;110(3):457-506.
https://doi.org/10.1007/s10994-021-05946-3
Abdar M, Pourpanah F, Hussain S, Rezazadegan D, Liu L, Ghavamzadeh M, et al. A review of uncertainty quantification in deep learning: Techniques, applications and challenges. Inf Fusion. 2021;76:243-97.
https://doi.org/10.1016/j.inffus.2021.05.008
Tomsett R, Preece A, Braines D, Cerutti F, Chakraborty S, Srivastava M, et al. Rapid trust calibration through interpretable and uncertainty-aware AI. Patterns (N Y). 2020;1(4):100049.
https://doi.org/10.1016/j.patter.2020.100049
Kompa B, Snoek J, Beam AL. Second opinion needed: Communicating uncertainty in medical machine learning. NPJ Digit Med. 2021;4(1):4.
https://doi.org/10.1038/s41746-020-00367-3
Begoli E, Bhattacharya T, Kusnezov D. The need for uncertainty quantification in machine-assisted medical decision making. Nat Mach Intell. 2019;1(1):20-3.
https://doi.org/10.1038/s42256-018-0004-1
Langer M, Oster D, Speith T, Hermanns H, Kästner L, Schmidt E, et al. What do we want from explainable artificial intelligence (XAI)? A stakeholder perspective on XAI and a conceptual model guiding interdisciplinary XAI research. Artif Intell. 2021;296:103473.
https://doi.org/10.1016/j.artint.2021.103473
Kaur D, Uslu S, Rittichier KJ, Durresi A. Trustworthy artificial intelligence: A review. ACM Comput Surv. 2023;55(2):1-38.
https://doi.org/10.1145/3491209
Li B, Qi P, Liu B, Di S, Liu J, Pei J, et al. Trustworthy AI: From principles to practices. ACM Comput Surv. 2023;55(9):1-46.
https://doi.org/10.1145/3555803
Glikson E, Woolley AW. Human trust in artificial intelligence: Review of empirical research. Acad Manage Ann. 2020;14(2):627-60.
https://doi.org/10.5465/annals.2018.0057
Shin D. The effects of explainability and causability on perception, trust, and acceptance: Implications for explainable AI. Int J Hum Comput Stud. 2021;146:102551.
https://doi.org/10.1016/j.ijhcs.2020.102551
Ananny M, Crawford K. Seeing without knowing: Limitations of the transparency ideal and its application to algorithmic accountability. New Media Soc. 2018;20(3):973-89.
https://doi.org/10.1177/1461444816676645
Zerilli J, Knott A, Maclaurin J, Gavaghan C. Transparency in algorithmic and human decision-making: Is there a double standard? Philos Technol. 2019;32(4):661-83.
https://doi.org/10.1007/s13347-018-0330-6

Author information

Ana Silva, Mohamed Al-Farsi & Luca Moretti contributed to this work.

Authors and affiliations

Department of AI and Reasoning Systems, University of Lisbon, Lisbon, Portugal
Ana Silva

Department of Computer Science, Sultan Qaboos University, Muscat, Oman
Mohamed Al-Farsi

Department of Information Technology, University of Milan, Milan, Italy
Luca Moretti

Corresponding author

Correspondence to Ana Silva

Rights and permissions

Open Access The author(s) retain copyright. This article is licensed under the Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License. It may be shared and adapted for non-commercial purposes with appropriate attribution, an indication of changes, and distribution of adaptations under the same license. Third-party material may be subject to separate terms identified in its credit line. View the license at https://creativecommons.org/licenses/by-nc-sa/4.0/.

About this article

Cite this article

Vancouver
Silva A, Al-Farsi M, Moretti L. Making Machine Reasoning Open to Question: An Integrative Review of Causal, Neuro-Symbolic, Knowledge-Grounded, and Uncertainty-Aware Explainability. J Trustworthy Explain Intell Syst. 2026;5:83.
APA
Silva, A., Al-Farsi, M., & Moretti, L. (2026). Making Machine Reasoning Open to Question: An Integrative Review of Causal, Neuro-Symbolic, Knowledge-Grounded, and Uncertainty-Aware Explainability. Journal of Trustworthy and Explainable Intelligent Systems, 5, 83.
Received
13 November 2025
Revised
10 January 2026
Accepted
09 February 2026
Published
15 March 2026
Version of record
15 March 2026

Share this article

Easily share this article with others using the link below:

Making Machine Reasoning Open to Question: An Integrative Review of Causal, Neuro-Symbolic, Knowledge-Grounded, and Uncertainty-Aware Explainability
Scan to access
this article

Ready to submit?
Start a new submission or continue a submission in progress:
Submission Portal Author Guidelines

Follow this journal
Get notified of new updates and articles.