Explainable vs Probabilistic Security: Why Auditors Care More Than Engineers

Understanding the critical differences between explainable and probabilistic security approaches and their implications for compliance.

January 15, 2026 Mark Ahearne, Founder & Director

The Fundamental Divide in Security Approaches

In the world of cybersecurity, two distinct philosophies guide how organizations approach threat detection and risk assessment: explainable security and probabilistic security. While engineers often favor the latter for its efficiency and accuracy, auditors and compliance officers prioritize the former for entirely different reasons.

What is Explainable Security?

Explainable security refers to security systems and processes that provide clear, understandable reasoning for their decisions and actions. When a security control blocks access or flags a threat, it can articulate exactly why that decision was made, citing specific evidence and logic chains. ISO 42001, the international standard for Artificial Intelligence Management Systems, establishes requirements for establishing, implementing, maintaining, and continually improving an AI governance framework within organizations, including explainability requirements for AI-driven decisions.

Probabilistic Security Approaches

Probabilistic security, on the other hand, relies on statistical models and machine learning algorithms to make decisions based on patterns and probabilities. These systems excel at identifying anomalies and predicting threats but often operate as "black boxes" where the internal decision-making process is opaque. The MITRE ATT&CK framework provides a comprehensive knowledge base of adversary tactics and techniques that can be used to understand and document attack patterns, helping organizations map probabilistic detections to known threat behaviors.

Why Auditors Prioritize Explainability

Auditors and compliance officers care deeply about explainability because their role requires them to validate that security controls are working as intended and that organizations can demonstrate accountability. Under frameworks like SOC 2, ISO 27001, and GDPR, organizations must prove that their security decisions are:

  • Auditable: Decisions can be traced and verified
  • Accountable: Responsibility can be assigned
  • Compliant: Aligned with regulatory requirements
  • Defensible: Can withstand legal scrutiny

The Engineering Perspective

From an engineering standpoint, probabilistic approaches offer superior performance. Machine learning models can process vast amounts of data, identify subtle patterns, and adapt to new threats faster than rule-based systems. However, this power comes at the cost of transparency.

Finding the Right Balance

The solution lies in combining both approaches. Modern security platforms should offer:

  • Explainable AI (XAI): Machine learning models that provide reasoning
  • Hybrid Approaches: Combining probabilistic detection with rule-based validation
  • Comprehensive Logging: Detailed audit trails for all decisions
  • Human Oversight: Escalation mechanisms for critical decisions

Key Takeaway: While engineers build systems for optimal performance, auditors ensure those systems meet compliance and accountability requirements. The most effective security programs bridge this gap through explainable, auditable, and performant solutions.

Related Insights

AI Accountability in Security

When AI makes security decisions, who bears the responsibility?

Read Article

Incident Response Playbooks

Why most incident response frameworks stop too early in the recovery process.

Read Article

Achieve Compliance with Explainable Security Solutions

Discover how IdentityFirst provides auditable, explainable security controls that satisfy both engineering excellence and compliance requirements.