The following sentence, which is part of a presentation of the doctrine of structural holism and is translated from the french, does not seem quite to make sense to me:
"each one [of the members of a system] is the system itself considered in one of its members."
Is this sentence logically correct or not? And if not, what is exactly the problem?
Is it possible to express this sentence in the language of formal logic?
What is exactly the meaning of "is" in this sentence?
Is there some sort of vicious circle here? or a contradiction?
Addition: After reading the first answer and comments, I realize I have to give some more information, in order to allow a better understanding of the possible or intended meaning of the sentence, as well as of the main words it contains.
A system, in the sense of structural holism, is an ordered pair or set, like a dyad, triad, etc. A system is a whole, and its parts, or members, are something different from elements or individuals put together. They are individuals taken under a description, which means they are considered in their reciprocal relationship and interdependance within the system, as fulfilling complementary roles, like giver/receiver/object given, or killer/victim.
The quoted sentence is taken (slightly modified) from a book by Vincent Descombes, The Institutions of Meaning, Harvard University Press 2014, and belongs to a passage commenting an example borrowed from Peirce, "Cain kills Abel" :
"What we add when speaking of a dyad rather than of two individuals is the idea that we are considering these individuals as the members of a dyadic system. Each of them is a dyadic unit; therefore each of them is the system itself considered within one of its members. Each of them is a dyadic unit because each is taken under a description: we are not speaking of Cain tout court; we are speaking of him insofar as he is a murderer."