About Definitional Rules: Rules Count!

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

Extracted from Rules: Shaping Behavior and Knowledge, by Ronald G. Ross, 2023, 274 pp, https://www.brsolutions.com/rules-shaping-behavior-and-knowledge-book.html

Definitional rules literally tell you what counts as an instance of a concept and what doesn't. Examples:

  • Does a tank top count as a shirt?

  • Does a prospect count as a customer?

  • Does a subsidiary's customer count toward a company's market share?

Ever wonder why different people can count the very same things and come up with different answers? Do you suspect key performance indicators (KPIs) you're going by aren't telling exactly the right stories? In referencing or applying a measure, how far might the truth have been stretched?

If you want to count anything precisely, you'll probably need definitional rules in addition to definitions. Come along on this short travel story and let's explore the matter together.

Personal Count of Cities-Visited

How many of the following cities have you visited? Count 'em up. I'll tell you my personal count at the end of the discussion.

The precision of your answer depends entirely on your definitional rules. Here are some questions you might want to ask about your personal city count.

  • If you connect flights in an airport but you never physically leave the airport, does that count as a city you've visited? For example, I have connected on same-day flights in and out of Singapore, but as a transient passenger I could not go outside customs. Does Singapore count for me?

  • If you are a passenger in a hired car without input about the route and you pass through a city without stopping or veering from the predetermined route, does that count as a city you have visited? For example, I have passed through Berlin on a chauffeured drive from Amsterdam to Dresden. Does Berlin count? (By the way we were mostly on the Autobahn after midnight, so the trip didn't take as long as you might think!)

  • If you were on a cruise ship that had an outbreak of a pandemic and you anchored at a port but could not leave the ship, would that city count? Luckily, I do not have a personal example of this case(!).

By the way, is Singapore a country or a city?! Better check the definitional rules on that!

The Freedom-of-Movement Rule

My daughter and I have had the same kinds of questions in a different travel game. We each keep track of the number of U.S. states and Canadian provinces we have visited. Like daughter, like father, we are both fierce competitors.

So, to resolve edge cases, we had to come up with a what-counts rule to go by. Rules help keep peace in the family(!) — just as for any other group or community of people. By the way, my personal counts for this state-and-province travel game are also at the end of this discussion.

Our solution was what we called the Freedom-of-Movement Rule. To say you have visited a state or province, you must have the opportunity (even if you don't necessarily take it) to move freely about. For the cities-visited game, the Freedom-of-Movement Rule would disallow counting Singapore and Berlin and any city where a quarantined cruise ship might have docked.

My daughter once drove us more than 50 miles out of our way in Minnesota to cross the border into Wisconsin so she could count that state. She just did a U-turn at the first legal opportunity. But Wisconsin counts for her — freedom of movement!

Actually, we were over the border for literally only 5-6 minutes. Do you think that's too short a time to count as a visit? What would your rule be for minimum length of visit? Do you think you should at least have to buy something (even if just gasoline)? Money talks of course. Or eat something? Or sleep a night there?

Here's another consideration. My daughter and I have mostly traveled by plane and automobile, seldom by train. Suppose you took a sight-seeing train trip across the continent, you ate and slept on the train, and never stepped off in some states or provinces. Would those count?!

Motivation Matters

The natural tendency in the city/state/province counts is probably to inflate. A higher number looks more impressive. But suppose I told you I was willing to finance your visits to places you've never visited. (By the way, I'm not.) Then you might be a little more conservative in your count. Motivation matters!

Or suppose the count is the crime rate in some place. You are a city official responsible for promoting your city to out-of-towners for tours, conventions, and conferences. You'd be tempted to discount the crime rate some, wouldn't you?!

My earlier visit examples and counts are all just games. Counts in business and government, however, are a serious matter. Want to be data-driven? If factual numbers matter to you, you'd better know the definitional rules!

Behavioral Rules and Definitional Rules

Behavioral rules can be specified without definitions and definitional rules, but such behavioral rules almost always prove vague and ineffective.

Consider a restaurant's (behavioral) No-Shirt, No-Service Rule. For it to be practical, you need a shirt definition to start with, then because of all the nuances of shirt, probably some (definitional) What's-a-Shirt Rule(s) as well.

Defining terms — and clarifying those definitions with definitional rules — is a fundamental necessity of rules for groups and communities of people. Ever hear of that little thing called 'terms and conditions'?![1]

My Personal Visit Counts

Here are my personal visit counts as of January 2022. They are actually the very same as in January 2020. I was planning many more visits in the intervening two years, but the pandemic, unfortunately, had other ideas.

My Personal Count of Cities: 29
My Personal Count of U.S. States and Canadian Provinces: 49 and 10, respectively

You might be curious which state I'm missing. The answer is Alaska, my planned 2020 trip a casualty of the pandemic. By the way, there are 10 provinces in Canada. Many (most?) Canadians have not been to all 10, so I do take a bit of pleasure in that particular count.


[1] For more about the two fundamental kinds of rules, refer to "The Two Fundamental Kinds of Rules," Business Rules Journal, Vol. 24, No. 6, (Jun. 2023),
URL: http://www.brcommunity.com/a2023/c120.html

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Standard citation for this article:

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Ronald G. Ross, "About Definitional Rules: Rules Count!" Business Rules Journal, Vol. 24, No. 8, (Aug. 2023)
URL: http://www.brcommunity.com/a2023/c124.html

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 BRCommunity.com 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 http://www.brsolutions.com/category/blog/. For more information about Ron visit www.RonRoss.info. Tweets: @Ronald_G_Ross

Read All Articles by Ronald G. Ross

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