Question: What is the business rules 'mantra'?

The traditional business rule mantra, a central idea of business rules, dates back to at least the mid-1990s. It is expressed in the Business Rules Manifesto (Article 3.1) this way:

Rules build on facts, and facts build on concepts as expressed by terms.

Perhaps not obvious in the statement is the insistence on declarative expression of business rules. When business rules are expressed declaratively, no meaning (semantics) is hidden in the sequence of the statements ("in between the lines"). Literally, you can read the statements in any order, and get the same meaning.

Liberating business rules from procedural means of capture and expression (e.g., processes, procedures, use cases, procedural languages, etc.) means that each statement can be validated on its own merit. It also produces the highest degree of reusability (for the business rules).

The importance of such independence is emphasized by the subtitle of the Manifesto: The Principles of Rule Independence.

What do you get when you express business rules declaratively? Encoded knowledge, or perhaps more accurately, know-how. The importance of capturing and retaining core business knowledge (know-how) is even more urgent today than when the Manifesto was written in 2002. It is emphasized by the heading of Article 3: Deliberate Knowledge, Not a By-Product (of requirements and IT development).

Additional Note: In early 2012, SBVR^[2] was revised to focus more directly on real-world language and concepts (always its original intent) . So the Mantra today would be more accurately expressed:

Business rules are based on verb concepts, as expressed by wordings. Verb concepts are based on noun concepts as expressed by terms.

Literally, you need nouns and verbs to write sentences. A good business rule statement, by the way, is always a sentence.

References:

[1] The Manifesto is free, only 2 pages long, translated into 15 languages. Have a quick look (or re-look!). No sign up required. Well worth your time.

[2] The OMG standard Semantics of Business Vocabulary and Business Rules. For additional discussion, see the SBVR Insider section on www.BRCommunity.com.

[3] For discussion, see 'Concept Model' vs. 'Fact Model' ... Where in the World Are the Instances? http://goo.gl/Oz6UA.