In one word: No,
the goyim don’t say he converted. Here’s what we’ve got to go on:
Aristotle was reported by Chazal to have said: “I do not deny the revelation of the Jews, seeing that I am not acquainted with it; I am occupied with human knowledge only and not with divine” (Judah ha-Levi, “Cuzari,” iv. 13; v. 14).
” Of Aristotle himself Josephus has preserved (“Contra Apionem,” i. 22) a very interesting passage from the writings of Clearchus, the pupil of Aristotle, the authenticity of which is maintained by such authorities as Lobeck, Bernays, von Gutschmid (“Kleine Schriften,” iv. 578), and Theo. Reinach (“Textes d’Auteurs Grecs et Romains Relatifs au Judaisme,” 1895, pp. 10-12). This passage, prefaced by the remark of Josephus, is as follows:
FRAGMENT OF CLEARCHUS.
[Palestine]. These Jews are derived from the philosophers of India. In India the philosophers call themselves Kalani, and in Syria Jews, taking their name from the country they inhabit, which is Judea; the name of their capital is rather difficult to pronounce: they call it Jerusalem. Now this man, who had been the guest of many people, had come down from the highland to the seashore [Pergamus]. He was a Greek not only in language, but in soul; so much so that, when we happened to be in Asia in about the same places whither he came, he conversed with us and with other persons of learning in order to test our wisdom. And as he had had intercourse with a large number of sages, he imparted to us more knowledge of his own.”
In other words, Aristotle’s student, Clearchus, says that this Jewish philosopher was Greek “in soul”; or as we say nowadays “Soul Brothers”. This fragment is all that exists as far as goyische sources go. All it really proves is that Aristotle had (at least) one Jewish friend. “Being the guest of many people” (who were probably goyim) seems like a hint that this Jew didn’t keep kosher. Of course, it could be that being a guest didn’t involve eating, or maybe they got him kosher food.
The goyim believe the conversion of Aristotle to Judaism is an “urban legend”. My guess is that the claims were made in the middle ages in response to the Rambam and other Rabbanim praising Aristotle.
So where did the urban legend come from?
The following letter first appeared written in Hebrew. It does not appear to be a translation. The source does not say whether the original was written in Ancient Greek or Aramaic. Aristotle writing a letter to Alexander the Great in any other language is very problematic. It’s also very problematic to say that a Jew discovered this letter over a thousand years after it was written, translated it, and could never come up with the original. But here it is:
Aristotle: Born 384 -322 B.C.
Birth: Chalcidice, Greece. Death: Chalcis, Greece.
When the great philosopher Aristotle was old, he sent the following letter to his student, Alexander the Great:
All my life I delved into philosophy, to explain all natural phenomena in a logical manner. I wrote many books on these subjects. Finally, in the twilight of my life, I had the opportunity to engage in a conversation with a Jewish sage. It did not take me long, to recognize his great wisdom; and he led me to understand, how great is the Torah, that was given on Mount Sinai.
He taught me the inner depth of the Torah, providing me with many brilliant insights based on its teachings. I realized how foolish I had been for not realizing, how G-d can manipulate the laws of nature; and that much of what happens in the world, is directed by G-d.
Realizing all this, I decided to devote myself to exploring the wisdom of the Torah. It did not take me long to realize, that the Torah is based on true foundations, while the axioms of philosophy are purely arbitrary.
__________
Therefore, my dear student Alexander, if I had the power to collect all the books I have written, I would burn them. I would be embarrassed for any of them to survive. However, I realize that I do not have this power; my books have already been published, and have spread all over the world. I also realize, that I will receive Divine punishment, for having written such misleading books.
Therefore, my son, Alexander, I am writing this letter to tell you, that the great majority of my theories regarding natural law, are false. While nature does exist, G-d is the Lord of the universe, and He directs all things as He sees fit. I am telling everyone openly, that they should not waste time with my books. They should not look at them, or even touch them with their hands. It is sinful to waste time, on the false theories that I have espoused.
I feel, that I have saved my soul by admitting my error; I hope that I will not be held guilty for the past, since I acted out of ignorance. But now I have revealed to the public that I was mistaken, and that my heart aches for the time I have wasted, on my foolish theories. Those who waste time on my books therefore, will deserve to be punished.
The Jewish scholar with whom I spoke, showed me the book of Proverbs (Mishley), written by King Solomon, one of the greatest geniuses of all times. The scholar showed me, that in many places, King Solomon warned against wasting time on philosophical speculation.
___________
I feel sorry for my eyes for what they have seen, and my ears for what they have heard. I feel sorry for my body, for wasting its strength on such detrimental studies.
I know that you praise me, and tell me, that I am famous all over the world because of the books I have written. People speak very highly of me. But I wish I were dead, because of the misleading books that I have spread all over the world.
People who devote themselves to the Torah, will earn eternal life; while those who devote themselves to my books, will earn the grave. But I am prepared to accept upon myself, the punishment of them all.
____________
I did not write to you earlier, because I was afraid that you would be angry with me, and perhaps even harm me. But now, I have made up my mind to tell you the truth. I know, that by the time you receive this letter, I will already be dead and buried, because I realize that my end is near.
Your teacher,
Aristotle
_______________________
Gedaliah ibn Ya?yah, Shalshelet ha-?abbala, ed. Warsaw, 1889, pp. 139, 140, under the heading of ?akme Yawan;
From Wikipedia:
“The value of this work is, however, lessened considerably by the fact that the writer has included many oral narratives which he gathered partly in his home, partly in Salonica and Alexandria, and that he often lacks the ability to distinguish truth from fiction. For these reasons the book has been called “The Chain of Lies”; but Loeb has proved that it is more accurate than many have supposed it to be. The Shalshelet ha-?abbalah was published at Venice, 1587; Cracow, 1596; Amsterdam, 1697; Zolkiev, 1802, 1804; Polonnoye, 1814; and Lemberg, 1862.”