The Two Fundamental Kinds of Business Rules Where They Come From and Why They Are What They Are

Ronald G.  Ross
Ronald G. Ross Co-Founder & Principal, Business Rule Solutions, LLC , Executive Editor, Business Rules Journal and Co-Chair, Building Business Capability (BBC) Read Author Bio       || Read All Articles by Ronald G. Ross

The SBVR[1] definition for rule is deeply embedded in formal logic, which deals with propositions.  In modal logic, propositions can claim different modes.  For business rules the two relevant modes are alethic and deontic.

  • Alethic rules are true 'by definition'.  As such they cannot be violated.  They are about how concepts, knowledge, or information are defined or structured.

  • Deontic rules are rules that can be violated.  They are rules about behavior, not concepts, knowledge, or information.  Deontic rules are really about people, what they must and must not do, even if their activity (and the rules) are automated.

Both kinds of rules are important, of course, but deontic rules — people rules — are especially so since, ultimately, businesses are about the activity of people.  This situation is very different than in the semantic web, for example, where it's all about only knowledge.

Under modal logic, every rule must therefore 'claim' one of two modes.  (In practice, the 'claim' arises naturally from the syntax of a rule statement or as a meta-property.)

  • Alethic implications (rules) are established by 'claiming' necessity.  Things are necessarily true.  A concept is what it is; says what it says.  That's just the way things are.

  • Deontic implications (rules) are established by 'claiming' obligation.  Behavior is 'obliged' to follow the rule.  But, of course, people don't always follow the rules so there can be violations.  Major difference.

So a rule 'claims' either necessity or obligation, which establishes what kind of rule it is.  Therefore the SBVR definitions for the two kinds of rule are:

  • Definitional rule:  rule that is a claim of necessity

  • Behavioral rule:  business rule that is a claim of obligation

Why doesn't the definition for definitional rule say "business rule" like the one for behavioral rule?  Because some definitional rules are not 'under business jurisdiction' (in other words, business has no choice about them).  Examples include the 'law' of gravity and all the rules of mathematics.  Those rules are simply universally true.

I recommend the following pragmatic definitions for business analysts.

  • Definitional rule:   a rule that indicates something is necessarily true (or untrue); a rule that is intended as a definitional criterion for concepts, knowledge, or information

  • Behavioral rule:  a business rule that places an obligation (or prohibition) on conduct, action, practice, or procedure; a business rule whose purpose is to shape (govern) day-to-day business activity
Synonyms:  Early in the development of SBVR, I introduced the terms structural rule and operative rule for the two kinds of rules, respectively.  That was before the full implications of modal logic became clear.  Since then the terms definitional rule and behavioral rule have become preferred, even in all internal SBVR discussion.  The synonyms, however, remain valid.

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[1]  For more information about SBVR see the SBVR Insider section on  return to article

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Standard citation for this article:

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Ronald G. Ross, "The Two Fundamental Kinds of Business Rules Where They Come From and Why They Are What They Are" Business Rules Journal, Vol. 15, No. 11, (Nov. 2014)

About our Contributor:

Ronald  G. Ross
Ronald G. Ross Co-Founder & Principal, Business Rule Solutions, LLC , Executive Editor, Business Rules Journal and Co-Chair, Building Business Capability (BBC)

Ronald G. Ross is Principal and Co-Founder of Business Rule Solutions, LLC, where he actively develops and applies the BRS Methodology including RuleSpeak®, DecisionSpeak and TableSpeak.

Ron is recognized internationally as the "father of business rules." He is the author of ten professional books including the groundbreaking first book on business rules The Business Rule Book in 1994. His newest are:

Ron serves as Executive Editor of and its flagship publication, Business Rules Journal. He is a sought-after speaker at conferences world-wide. More than 50,000 people have heard him speak; many more have attended his seminars and read his books.

Ron has served as Chair of the annual International Business Rules & Decisions Forum conference since 1997, now part of the Building Business Capability (BBC) conference where he serves as Co-Chair. He was a charter member of the Business Rules Group (BRG) in the 1980s, and an editor of its Business Motivation Model (BMM) standard and the Business Rules Manifesto. He is active in OMG standards development, with core involvement in SBVR.

Ron holds a BA from Rice University and an MS in information science from Illinois Institute of Technology. Find Ron's blog on For more information about Ron visit Tweets: @Ronald_G_Ross

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