A common question, and sometimes dilemma, of the Jew in the Diaspora is the extent to which we can and should acculturate into our host nation. Those who are halachically observant know to draw the line at celebrating Christmas and Halloween, despite the secularization of these days. But what about more innocuous things like New Year’s Day, or positive days like Thanksgiving? While most would agree that wearing distinctly Christian clothing, like a cross and collar, would be a violation of Jewish law, what about wearing generic “non-Jewish” clothing, like a white wedding dress or a bow tie?
In Parshat Achrei Mot the Torah tells us: You shall not copy the practices of the land of Egypt where you dwelt, or of the land of Canaan to which I am taking you; nor shall you follow their laws. (Vayikra 18:3)
The latter part of this verse, “nor shall you follow their laws” is the source for the prohibition of Chukat Akum, engaging in distinctly non-Jewish practices. But again, how do we measure what is non-Jewish?
The Torah specifically frames the prohibition of Chukat Akum in the context of the not copying the ways of the Egyptians and Canaanites. Therefore, perhaps one can argue that the scope of the prohibition should be limited to whatever the Egyptians and Canaanites were doing at the time.
Rashi, commenting on this verse, writes that the reason these two nations were singled out was because they were the worst of the worst. Not all the non-Jewish nations were bad, perhaps some were quite civil and pleasant. But Egypt and Canaan were really bad. The Torah therefore tells us to avoid acting like them. (See the Ramban on this verse who explains their specific ill behaviors.)
According to this read of the verse, the Torah outlawed following the ways of the other nations specifically because the other nations, those mentioned in the verse, were doing bad things. However the argument could be easily made that the Torah never meant to prohibit innocuous activity. In fact, this is the approach of the Ran quoted by the Rama in Shulchan Aruch Y.D. 178.
The Bechor Shor disagrees. The Bechor Shor writes that the reason the Torah listed the Egyptians and the Canaanites was not because they were any worse than any other nation. Rather, the Bechor Shor writes that those two nations were mentioned because they were the frame of reference for the Jewish people. Rather than a blanket statement about avoiding non-Jewish conduct, God sought to remind the people what non-Jewish conduct looked like. The Jews, having recently left Egypt, knew what it meant to dress and behave like an Egyptian. And the Jews would soon know what it meant to act like a Canaanite. These were examples of all other nations, and not examples of the worst other nations.
According to this alternate read of the verse, the Torah outlawed following the ways of the other nations regardless of any specific corrosive behavior. This is the opinion advocated by Tosaphot in Avodah 11a, against the approach of the Ran. (It is by no coincidence that the Bechor Shor was one of the Baalei Hatosaphot.)
As a postscript, it’s important to note that most halachic authorities tend to follow the opinion of the Ran on this matter.