"sem" eða "og"?

Modern Icelandic differs from Old Icelandic (which I learned in school) in of course a number of ways, the vocabulary being especially changed (names for weapons and wounds are oddly enough less important these days). But I find myself continually stumbling over the fact that modern Icelandic has expanded the meaning of the word "og." That word has the same historic root as "and" in English, and indeed is still used in that way: it marks objects in a series (I bought eggs and bread and milk at the store). In that sense it signifies equality, that all the objects mentioned are equally important.

But modern Icelandic also uses "og" in places where English would use a subordinate conjunction, such as "that" or "which". For example, in English we would say, "A law was passed that makes it legal to hunt whales" but in Icelandic they say, "A law was passed and it is legal to hunt whales." There is an implied hierarchy there, based on which statement comes first, but really such a construction requires the readers/listeners to recognize the logical subordinate position of the subsequent phrase, even if there is no explicate linguistic marker signifying that relationship.

Old Icelandic used to mark this more clearly, through the use of the word "sem" (translated as "that"). When I speak modern Icelandic, I sometimes find myself saying "sem" when I ought not, just because my linguistic habitus wants to more clearly articulate which is the subordinate clause. But that really is so old school of me. Modern Icelanders can tell without anyone saying so.