It is written in the SEP:
Identity is often said to be a relation each thing bears to itself and to no other thing (e.g., Zalabardo 2000). This characterization is clearly circular (“no other thing”)'.
The question is: what is circular here?
Deutsch, Harry and Garbacz, Pawel, "Relative Identity", The Stanford Encyclopedia of Philosophy (Fall 2018 Edition), Edward N. Zalta (ed.), URL = https://plato.stanford.edu/archives/fall2018/entries/identity-relative/.
It's circular because "no other thing" just means "no non-identical thing" which uses the identity relation that is to be defined.
Another way to define the identity relation is to say that it's the smallest equivalence relation (e.g., in the SEP entry on identity). That's also considered circular because it refers to all equivalence relations, including identity itself. (Definitions of this kind are called impredicative). Whether or not this kind of circularity is bad is another matter. You can read about it in the IEP entry on predicative and impredicative definitions.
We can see also Ludwig Wittgenstein's Tractatus :
5.5303 Roughly speaking, to say of two things that they are identical is nonsense, and to say of one thing that it is identical with itself is to say nothing at all.
The first sentence in the SEC entry has no bearing on identity. The basic, fundamental error is that self – identity is being cited as - ‘a thing onto itself’. Identity has nothing to do the structure of a ‘self’ as a ‘thing’.
We tend to stay where we feel comfortable, even if that does not provide us with a social status in our community. The experiences of belonging in a personal sense, often replaces belonging in a larger social sense. ‘Relativism’ – the distinction that ‘all things, experiences and values are relative’ – has, at it’s roots, the cultural legacy of identity we receive in the language we speak. Cartesian dualism, Machiavellianism, religious teachings and even gender, create our learned identity of a referential entity we call ‘my -self’. It is through our experiential attachments that we create connective values to our comfort and inclusive / exclusive needs.
Whether it be a collective or an individual connection, identity is a referential abstract containing statuses of inclusions and exclusions. We know ‘Who’ we are by experiences, connections to other social beings, and, by our sentient physical existence.
