Is a Definition Just a List of Attributes?

If we look at a data model, is a definition of an entity type automatically produced by listing the attributes of the entity type?  If this were true then a data modeler would not need to produce entity definitions - he or she would simply need to identify and list a sufficient number of attributes.  I have actually heard data modelers being criticized by terminologists for doing just this.  The extent to which such criticism is fair or not is a separate discussion, but the question remains as to whether a list of attributes can suffice as a definition.

I do not think that a list of attributes is sufficient based on the recent discussions about concept systems in this blog.  No concept exists in isolation.  Every concept exists in some kind of concept system where it has relationships to other concepts.  At least some of these relationships and/or related concepts have to enter into a definition so that the concept being defined can be located properly in a concept system, which appears to be necessary for knowledge.

A list of attributes usually will not distinguish between those that are determining for the concept under consideration, and those which are not - some of which may be shared with other concepts.  Thus, just reviewing a list of attributes becomes a test of figuring out which ones are pertinent to a definition.  This surely defeats the practical aspects of definition.

It would seem therefore that something more than a list of attributes is required to produce a quality definition.  While many data modelers do produce quality definitions, it can be seen that the practice of data modeling may present the temptation to just assume that the definition of an entity type is provided by the attributes captured for it.  Of course, relationships and other concepts are present in a data model, but it will need another blog to answer the question of whether a data model has enough information to produce a definition based on entity types, attributes, and relationships alone.

On Roles, Attributes, and Definitions

Dave Hay commented on my post How Many Attributes Do I Have?  Dave notes that there is a difference between me and the roles that I play.  This is an important point that I struggled with previously.  Dave states "most of the examples are attributes of my role as a customer", meaning the examples I provided in my post.

"Role" is a term that gets bandied around a lot in data modeling.  In my previous post on Role vs. Relationship I argued that roles really refer to certain kinds of relationships.  However, Dave's point is one that I have heard on a lot of occasions and has to be taken seriously.

Let's state the question this way: is the attribute Customer Lifetime Value to Hardbitten Liquors an attribute of me, or an attribute of my role as a customer of Hardbitten Liquors?  And if the latter, just what do we mean by "role".

There is no doubt that I am an instance of a concept.  The concept is human being.  Further, Customer Lifetime Value to Hardbitten Liquors can be predicated of me, strongly suggesting it is an attribute I possess.  

But now let us think of the role that is being suggested in this discussion.  What is it?  Is this role "Customer of Hardbitten Liquors"?  If so, I would argue that this is a relationship between me and Hardbitten Liquors.  And if an entity type has attributes, and relationships do not, then we cannot say that a role has any attributes.

But suppose Dave is right and the role does have attributes.  It will have to be an entity of some kind.  What other thing could the role be - apart from "human being".  There is a possibility.  Suppose I only ever bought one bottle of Grandpa's Tipple from Hardbitten Liquors.  Then, my entire relationship with Hardbitten Liquors could be encompassed by this one event - the purchase of this one bottle.  Now, Purchase is an entity type, albeit non-material, so it can at least be a candidate for the role.

But can Purchase really be the same as role?  I do not think that an event can have an attribute such as Customer Lifetime Value to Hardbitten Liquors, which really refers to the individual customer.  And I do not think this can be true of any aggregate of instances of Purchase events either, supposing, for instance, that I buy one bottle of Grandpa's Tipple every week.  

So if role is not to be identified either with me or my purchases, what other entity types can it be identified with?  I need to do some more research to be able to answer that.  However, for now I am still going to stick with attributes like Customer Lifetime Value to Hardbitten Liquors as being an attribute of me.  So my original point provisionally remains: a concept can have a vast number of attributes and some methodology is needed to decide which ones to include in a definition.