Philadelphia named for an incestuous relationship?

I’m back from the library, but I have no definitive answers. [ul][li]Philia can refer “fondness between lovers”, but that is a relatively late usage. Late compared to what, I don’t know. The Ptolemaic dynasty was late compared to, say, the time of Pericles. The original use of the word is to denote affectionate regard amongst family members, friends, etc.[/li][li]The word philadelphos meant brother-loving (in the non-incestuous sense) long before Ptolemy and Arsinoe. It was used in this sense by Xenophon among others.[/li][li]Philadelphia (the word, not the place) occurs in the Greek New Testament, in Romans 12:10 (among other places): “Be kindly affectioned one to another with brotherly love; in honour preferring one another;”[/li][li]Arsinoe II apparently was referred to as “philadelphos” in her lifetime. There are inscriptions bearing the name “Arsinoe philadelphos” that seem to imply she was still alive when they were made.[/li][li]Those biographers of William Penn who mention the subject at all agree that he probably named his city directly from the Greek roots, and not after the old-world cities of the same name. He was apparently a classicist as well as a biblical scholar, and so he was probably familiar with both the Greek word and the old-world cities. One biographer mentioned speculation that he may have been inspired by the “Philadelphians”, a kind of religious movement (?) that many Quakers belonged to.[/li][li]Both the Greeks and Macedonians were scandalized that full siblings would marry, even though half-sibling marriage was not uncommon in Macedonia.[/ul][/li]
My primary remaining question is whether or not Arsinoe was called “philadelphos” before she married her brother. As don Jaime said,

This makes me think the name “philadelphos” may have been bestowed on her because she showed devotion to one or more of her brothers long before she married Ptolemy.

Are you sure about that? This site, for instance, says she was:

The source the site uses is apparently The Columbia Encyclopedia: Sixth Edition. Now, I won’t claim that because the information that Berenice was Ptolemy I’s half sister appears in an encyclopedia it has to be true, especially since I don’t know what primary sources the encyclopedia has used, but I am curious as to what sources you have that claim she isn’t.

I spent a bit of time trying to find a site online that would specify who Ptolemy I’s and Berenice’s parents were (to see if they did indeed share a common parent), but without much luck. A site run by an organization called the “Princeton Economic Institute” gives some history on Ptolemy I (apparently as background on the coins of the time) and says:

But does not specify who Ptolemy I’s mother was, and doesn’t mention Berenice’s parents at all.

Interestingly, in an arcticle about Arsinoe II it also makes some claims about why she might have married Ptolemy II.

I’m not sure how accurate the above is in terms of Arsinoe II and Ptolemy II’s actual motivitations (and it doesn’t strike me as the most scholarly of sources, especially considering the grammatical errors), but I thought it was interesting nonetheless.

Amok,

My opinion is Ptolemy married Arsinoe to ensure no one else could. As his sister, and daughter of the previous king, she already had prestige in Egypt. She had to be married off to somebody trustworthy to ensure this power wasn’t used against him. Given the complicated marriage politics and the perfidity of their own half-brother Ptolemy Keraunos, Ptolemy II probably decided he was his own safest option. It could also have served to renew her Egyptian prestige, like this other one says, since she had been more important in Makedonia than Egypt for so long. And Ptolemy and Arsinoe could just be sexual deviants. We’ll probably never have the full answer. The flaw in all these arguments is the real chance that a disgusted populace would have revolted against Ptolemy and Arsinoe, negating whatever beneficial effect they were after.

I can’t remember what I cited for Ptolemy I and Berenike. I’m wanting to say Bevans, but I don’t think that’s right. I’ll have to look it up again. I do recall that their parents had different names.

Walter Ellis in “Ptolemy of Egypt” (1994) says contemporary acounts list Ptolemy’s parents as Lagos and Arsinoe and Berenike’s as Magas and Antigone. She came to Egypt as a lady’s maid to Ptolemy’s previous wife. A later commentary by Theokritos claimed she was a half-sister to give her family prestige and to help legitimize the full sibling mariages of the later Ptolemies.

Actually, he got the sig from the Oracle at IllaDelphi.

Makes sense. Thanks for the reference. I guess that would have made Ptolemy II and Arsinoe II’s marriage seem even more odd. As bibliophage already stated, it appears the greeks at the time were quite shocked by the marriage. Whether the common people of Egypt would have been, I’m not sure.