Relations, real and logical and so on

Banzelao Teixeira asked a question about relations: "Would you be explain to me the difference between relatio secundum esse and relatio secundum dici????" 

My reply:

not sure of the Latin.

literally, it seems to translate: "relation according to being", and "relation according to saying."

perhaps it is a way of talking about "real relation" and "notional relation" or perhaps "logical relation."  

i think you should try asking JD...

Here's Lonergan, Insight, p. 514 of the CWL 3 edition:

in any pair of correlatives, we can distinguish between a relation, its base, its term, and the converse relation, base, and term.

E.g. the relation 'father' has Abraham as its base, and Isaac as its term.

the converse relation 'son' has Isaac as converse base, and Abraham as converse term. 

relations may be notional, problematic, real or mixed.

they are notional if they are merely supposed, merely objects of thought.

they are problematic if their affirmation occurs in a description or in a provisional explanation.

they are real if their affirmation would survive in a definitive explanatory account of the universe.

they are mixed if one correlative is real, and the other is notional. 

The correlatives Ivo and Amish.

relation uncle has Ivo as base and Amish as term

converse relation nephew has Amish as converse base and Ivo as converse term.

Is the father-son relation the same as the uncle-nephew relation?

Or better: is uncle-nephew notional, problematic, real or mixed?

Going by the above, it would appear that uncle-nephew is real, as real as father-son; since the reality or lack of it depends not on causality but on the reality of the terms. In other words, it is not only efficient causal relations (father-son) that are real. There are many other types of real relations. Father-son would be a relationship of efficient causality (efficient cause – effect). Uncle-nephew would not be a relationship of efficient causality, or at least not directly so.

Internal and external relations. (517)

Internal: when the concept of the relation is intrinsic to the concept of its base.

External: when the base remains essentially the same whether or not the relation accrues to it.

Both internal and external relations survive in a definitive explanatory account of the universe. (518)