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Note: Reader mail (rm) posts are exchanges with my readers that raise fundamental issues. I may improve language for clarity and amplify with Ed. Notes for the benefit of readers.

“Your post Understanding Conceptual vs. Data Modeling Part 1: Data Model - The RDM Is, the E/RM Isn't is well done. However, concepts and relationships can be perceived and modeled without formulating or specifying properties. Chen did that in his ER diagrams. And informally, everyone does it as a mental model every day. I suppose anyone can define conceptual modeling however they wish to.  But at its minimum and most abstract, which is what conceptual modelling is usually understood to be, it can be done without formulating or specifying properties.” --GR

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Ah, yes, after "well done" I expected a however :).

Of course they can be! Perceptions/conceptual models are not-scientific, which is why formalization is needed for database representation and manipulation. The question is: what is most useful for that objective.

I am currently working on version 2 of my Relationships & RDM series of posts and when I publish it you will see why we have a different perception/conceptualization that includes properties.

With respect to Chen specifically, see below.

Again, of course they can, but:

“... singular names, property terms and class terms correspond to common sense concepts of individual beings, traits or activities of individual beings and sets of beings who share some common traits or activities ... This three-fold distinction is an important part of our Western intellectual heritage and is deeply embedded not only in our thought habits, but also in our language. --Olson, R., MEANING AND ARGUMENT: ELEMENTS OF LOGIC

Emphasis mine.

 

Ed. Notes

1. And properties are fundamental for good reason, even though it is missed, as we explained in Understanding Conceptual vs. Data Modeling Part 4: Properties-object Modeling (PoM). 
 
2. Another angle on this from the forthcoming revision I mentioned above: “In our conceptual modeling approach relationships between entities within a group and between groups are collective properties of the group and the multigroup, respectively.”

3. As to Chen specifically:

“Chen did use properties -- he called them attributes. He understood both the importance and necessity of properties at the conceptual level. If E/RM is being used for conceptual modeling without properties (Chen's attributes), it is obviously being misused! I suggest everyone actually read Chen's Turing Award paper The Entity-Relationship Model-Toward a Unified View of Data (See especially Fig.1 on page 3). Anecdotal accounts of what E/RM is and how it should be used can be misleading, and dangerous.” --David McGoveran (was acquainted with Chen in the 1980s and early 1990s)