To what degree is the Old Testament anti-semitic?

Example:
Deuteronomy 28 (King James Version)

Note that verse 64 makes it clear that the reference is not to people who practice Judaism, but to descendants of the audience who practice any religion that is different from Judaism. It promises collective punishment of people based on their ancestry.

how in the world is that passage anti-semetic? (assuming you are defining "Semetic" as "Jews")

Is it not prejudiced to promise punishment of people based on their ancestry and based on them not following practices prescribed in the OT? The fact of not following those practices can take the form of absence of religion or any religion that differs from what is prescribed in the OT.

semites include pretty much every middle eastern tribe, including assyrians, etc. I wasn't sure if you were using the common usage, or the historical/anthropological usage.

But all that aside, the OT is Judaism (well, part of it). It may very well advocate prejudice, but it is from the context of being within the jewish faith. It is not inherently anti-jewish. It's like saying that Christ saying one must believe in him to enter into heaven makes the New Testament anti-christian :shrug:

Are you sure that the parts of the NT that command belief in Jesus aren't anti-Christian? I suppose it depends on how one defines "Christian." For example, in the following quote Jesus doesn't try to define the word "Christian", but he does identify only two things that -- in his opinion -- one must do "to inherit eternal life." If there's a third item that he omitted, then what is it? Are you sure that he would say that after the two things he identified, the one next in importance is believing in Jesus?

"Anti-Semitic" has had a well-established lexical meaning for over a century.

It has a possible compositional meaning: anti- + Semitic. "Anti-Semitic" would mean being opposed to Semites. If you're a linguist, that includes Ethiopians, Eritreans, and Somalis, not just Jews and Assyrians and Socotrans and Arabs. If you're an ethnologist, you have to slice-and-dice the Semitic speakers into groups, presumably, mostly based on some sort of substratum ethnic type. At least some ethnologists would exclude the African contingent because they need a convenient term for people living in the extreme SW of Asia (some include N. Africans, some don't--most N. Africans in the Maghreb are mostly Berber, almost-but-not-quite Semitic, per most linguists and certainly contra Qaddhafi).

"Semite" is a funny ethnonym, in any event. It's really best seen like "Aryan" used to be, a linguistic group.

However, "anti-Semitic" would be "anti-" Semites in general, not any specific group, if you go for the compositional reading. Again, for Gricean reasons, essentially because of the principle of maximality: say all you can. (So anti-European can't properly be construed to mean just "anti-Andorran".)

Oddly, there are a number of words in English that have clear, common lexical meanings and uncommon compositional meanings, but which are disputed and interpreted only or preferentially to have compositional meanings. (Sometimes you can describe both meanings as compositional, but not in a straight-forward manner: often there's a bit of of coercion, the linguistic kind, involved.) Usually the disputes are there not to enlighten, but to obfuscate, distract from the topic, and produce either confusion and shut down the discussion or provoke outrage and shut down the discussion, or at least change the topic. Both point to the etymological fallacy, and both use language not to communicate, but to forestall communication.

There's a lot of that kind of behavior in US and world politics. If conversation involves a speaker saying words in order to express his/her meaning as well as a hearer who has to employ good will in order to construe the most likely meaning (something Grice would probably agree with, in principle), then the reason is obvious: If you can wrest control of the process, you can wrest control of the conversation. Then you privilege yourself as speaker and yourself as hearer, and disenfranchise the other in the conversation. Even if you can't wrest control, you can still attempt a sufficiently plausible smear to make the other guy stop and defend himself. Power politics motivates this kind of lack of cooperation in discourse. (The other common kind is even less enlightened: People simply don't want to hear opinions that don't echo and reinforce their own. http://www.sltrib.com/opinion/ci_8964560 seems appropriate here.)

It would be an open forum like "Economy", "Education", "Justice", or "Poverty."

I mean the Amelekites, Canaanites etc were pretty much Semitic surely?

I see some potential difficulties with your analysis:

1. There are debates about whether or not a man anything like Jesus ever lived. What information from outside the OT do you have to substantiate the claim that there was in fact a genocide of Amelekites and Canaanites?

2. It seems that you are analyzing the word "anti-Semitic" as meaning hostility to anyone of a Semitic ethnicity, but that doesn't seem to be the ordinary meaning of the word, either as originally used or as it is used today.

Also, it might be worth noting that unless, for example, there are currently some communities of adherents of Judaism who stone a woman to death when she is caught in the act of adultery, the OT is not today accepted as a literal prescription for actual practice.

a simple reminder that Semites are not always Jews, and also one that whatever horrors are in the bible are pretty evenly distributed.

Not everything is intended to be detailed exegesis, nor is every topic worthy of it.

You would have to make a distinction between each meaning of the word "semitic". Which one are you using?

Throughout history, antisemitism has been directed against Judaism and its values. Not against all semitic people.

Antisemitism was another word coined for judenhass (Jew-hatred) by Wilhelm Marr. Marr wanted to replace judenhass with a word that would make Jew-haters sound less vulgar and even somewhat "scientific" (as if Jews were a race).

Hitler himself had no compunctions about welcoming (Semitic) Arab leaders to Berlin during World War II. Does that mean that Hitler was not an antisemite?

Actually, that's weaselly, even for me.

Try #2, for clarity: There's almost no chance that the Philistines were Semitic.

The Philistines were one of the groups that formed the Sea Peoples (aka "Peoples of the Sea", as though that makes things any clearer). There's a bit of controversy as to where the Sea Peoples came from.

Currently I think I buy Woodhuiser's analysis: They were a confederacy, with a number of European (yet not Indo-European) and Anatolian (at least partly Indo-European) groups represented. I don't recall hearing that any Semites formed the Sea Peoples, in his view.

I have heard, and currently reject, the view that the Israelitish tribe of Dan was among the Sea Peoples, part of the argument that either Dan migrated out early (and went elsewhere: Anglo-Israelism's take on the matter) or were Sea Peoples that were integrated into the Israelitish confederacy (i.e., they migrated in around the same time as the various Israelitish tribes, and may or may not have been Semitic). But in any event, Dan and the Philistines are distinct groups.