Here are a few more observations on the term "tathagata" and the ways in which it is used, before we move on to other topics. I do not think that we should spend much time on it as there is already a thread where Tiltbillings and others discuss the meanings of "tathagata", see :viewtopic.php?f=23&t=218&p=1871&hilit=+tathagata#p1871
I first learnt of this from Bhikkhu Nanananda in his interesting book: Concept and Reality, in early Buddhist thought. Buddhist Publication Society. Kandy, Sri Lanka. 1986. This is a quotation from page 111 :
"The term "Tathagata" in its wider sense of the Perfect Man (uttamapuriso, paramapuriso, paramapattipatto, S.N. IV 399) is applicable to the Buddha as well as to the emancipated monk (vimuttacitto bhikkhu, M. N. I. 140, 486)".
Nanananda, a former lecturer in Pali at the University of Sri Lanka, had the advantage of reading the texts in the original Pali, while I had been reading English translations with their constant repetition of "The Tathagata", which it could be just as correct to translate, in many places, as "a tathagata".
The old PTS dictionary says, in its entry for "tathagata" page 296 :
" ...The context shows that the word is an epithet of an arahant ..."
Here are extracts from two interesting suttas :
" ... It is because he has fully awakened to these Four Noble Truths as they really are that the Tathagata is called the Arahant, the Perfectly Enlightened One. ..."
Bhikkhu Bodhi, Connected Discourses of the Buddha, page 1854.
Samyutta Nikaya. Part V Mahavagga. Chapter XII The Truths. III 23 (3) Arahants.
The next Sutta includes :
"At Savatthi. "Bhikkhus, whatever Arahants, Perfectly Enlightened Ones, in the past fully awakened to things as they really are, all fully awakened to the Four Noble Truths as they really are . Whatever Arahants, Perfectly Enlightened Ones, in the future will fully awaken to things as they really are, all will fully awaken to the Four Noble Truths as they really are. Whatever Arahants, Perfectly Enlightened Ones, at present have fully awakened to things as they really are, all have fully awakened to the Four Noble Truths as they really are". III 24 (4).
Lets try translating these passages in a slightly different way :
"...It is because he has fully awakened to the four noble truths as they really are that a tathagata is called an arahant, a perfectly enlightened one ..."
"... Whatever arahants, perfectly enlightened ones, at present have fully awakened to things as they really are, all have fully awakened to the four noble truths as they really are ..."
If you accept that there is more than one tathagata (at present) then the second passage is talking about tathagata's.
Best wishes, Vincent.