Business rules and rule-based systems

Business rules are quite popular these days, certainly the declarative specification of these things in computer programs in the shape of 'natural language' (yes, cool tools exist nowadays), so that core corporate decision logic (part of the corporate memory, so to say) is not hidden, but inspectable, maintainable and reusable. Hold on, say that again? What did we try to do back in the 80s (and some even earlier): try to build rule-based systems, using algorithms that I almost forgot, but I was quickly refreshed by the AI depot