What is rule-based explainability in AI?

Rule-based explainability in AI refers to systems where decisions are made using predefined, human-readable rules, allowing users to trace outputs directly to specific logical conditions. Unlike machine learning models that learn patterns from data, rule-based systems rely on explicit if-then statements crafted by developers. For example, a fraud detection system might include a rule like “if a transaction exceeds $10,000 and occurs in a foreign country, flag it for review.” Each decision can be mapped to the exact rules triggered, making the reasoning process transparent and auditable.

These systems work by evaluating input data against a set of rules stored in a knowledge base. Each rule consists of a condition (e.g., “user age < 18”) and an associated action or conclusion (e.g., “deny access”). When a query is processed, the engine checks which rules apply and executes the corresponding actions. For instance, a medical diagnosis tool might use rules like “if patient has fever and cough, recommend testing for flu.” Developers can inspect the rule set to understand why a decision was made, modify problematic rules, or add new ones. This approach is common in expert systems, compliance checkers, or applications requiring strict regulatory adherence, where traceability is critical.

The main advantage of rule-based explainability is its transparency: developers and users can validate logic without reverse-engineering complex models. However, scalability is a limitation. Writing and maintaining rules for dynamic or ambiguous scenarios (e.g., natural language processing) becomes impractical compared to data-driven ML approaches. For example, a rule-based chatbot handling customer support might struggle with nuanced queries not covered by existing rules, whereas an ML model could generalize better. Despite this, rule-based systems remain valuable in domains like finance or healthcare, where explainability is legally mandated, and errors in logic must be quickly identified and corrected.