The root of many problems is the flawed definition of "rule" in SBVR,
which differs from the sense that was intended in the formal logic
appendix. The SBVR definition is also at odds with the dictionary
definition of "rule" and includes some riders that seem a little
The intended meaning of "rule" in the formal logic appendix was the
dictionary meaning of the term. The definitive source (the ODE - Oxford
Dictionary of English) has the following:
Rule (core meaning)
"One of a set of explicit or understood regulations or principles
governing conduct or procedure within a particular area of activity."
Rule (main subsidiary meaning)
"A law or principle that operates within a particular sphere of
knowledge, describing or prescribing what is possible or allowable."
You will recall that when we tried to make such a definition explicit in
the revision of the formal logic appendix there was vehement opposition
from some members of the FTF, and we were obliged to indulge in the
unhappy compromise of using the term "logic rule" to mean the above
(although it is indeed the correct definition of "rule").
By the way, the ODE defines "logical" as:
"Of or according to the rules of logic."
(and, yes, it does dare to say "rules"!)
In contrast, here are the relevant SBVR definitions:
Definition: element of guidance that introduces an obligation or a
necessity Dictionary Basis: standard by which something is judged or
valued; criterion [MWUD (2B) 'rule'] Dictionary Basis: principle or
standard by which something may be judged or decided [determined] [NODE
'criterion'] Dictionary Basis: standard on which a judgment or decision
may be based [MWCD (2) 'criterion']
element of guidance
Definition: directive that is actionable, whose purpose is to advise or
inform with a goal of resolving a problem or difficulty, especially as
given by someone in authority
Necessity: No business policy is an element of guidance.
Definition: means that defines or constrains some aspect of an
enterprise General Concept: proposition
Note: This sense of 'means' (as in 'ends and means', rather than 'is
meant as') arises from the Business Motivation Model.
Note: Intended to assert business structure or to control or influence
the behavior of the enterprise.
Note: Its formulation is under the enterprise's control by a party
authorized to manage, control or regulate an enterprise, by selection
from alternatives in response to a combination of assessments.
Dictionary Basis: an official or authoritative instruction [NODE]
directive is actionable
Concept Type: characteristic
Note: 'Actionable' means that a person who knows about the directive
could observe a relevant situation (including his or her own behavior)
and decide directly whether or not the business was complying with the
directive. Dictionary Basis: subject to or affording ground for an
action or suit at law [MWUD 'actionable'] Dictionary Basis: a thing done
: DEED [MWUD (5a) 'action']
Note: The sense intended is: "It's actually something you can put to use
As you can see, SBVR effectively treats "rule" as a synonym of
"criterion". I fear that this is fundamentally incorrect. The ODE says
that a criterion is: "A principle or standard by which something may be
judged or decided." The ODE does not equate "criterion" with "rule", as
the SBVR definition implies.
For example, a bank may decide that one criterion for determining that a
customer should be treated as a Gold Customer is the length of time they
have held an account. Another criterion might be balance held in the
account, averaged over some period. The bank might then define a "Gold
Customer" rule that uses these (and probably other) criteria. In simple
cases, a rule may boil down to not much more than a single criterion,
but that does not change the fact that "rule" and "criterion" are
different concepts, and are clearly identified as such in the ODE. It's
hard to see what SBVR gains by attempting to muddle the two together.
Why not let "rule" simply mean "rule"?
A second problem is the use of "actionable" in the SBVR definitions. The
intent of SBVR was to provide business level descriptions, not
prescriptions for processing. It may well be that a rule necessitates
some actions at a machine level, but that should be outside the SBVR
scope. It's hard to see how alethic constraints fit with the SBVR idea
of "actionable". For example, how does one "action" something like "a
person is born in exactly one country"? A strict interpretation of the
current SBVR definitions would appear to disallow alethic constraints of
The dictionary justification quoted for "actionable" (and, by
inheritance, "rule" too) is also rather weird – I doubt that many
business rules are framed with legal action in mind.
A further problem is the demotion of a rule to just being a piece of
advice or information, rather than defining what must or must not be the
case. A rule may advise or inform, but that's not necessarily its
primary purpose, as claimed in the SBVR definitions.
In summary, the SBVR definition of "rule" could be paraphrased as "an
advisory criterion used to invoke a deed for which one could be sued",
which is very different from the ODE definition (and the common English
usage) of "rule". This SBVR meaning is NOT the meaning intended in the
formal logic section. Simply replacing "logic rule" by "rule" without
changing the SBVR definition of "rule" would therefore change the
meaning of the formal logic section.
A common-sense solution would be to change the term in SBVR from "rule"
to something like "SBVR rule", so that the term "rule" could be used
where necessary in its normal English language sense. In this case,
"logic rule" in the formal logic section could revert to just being
"rule" and no definition would be necessary since we would be using it
in its everyday sense. Where we can use ordinary English words in their
ordinary English sense it's hard to think of any reason why we should
not do so.