Let us take a look at Samaw’el’s polemical arguments in his Ifḥam al-Yahûd.
The work is organized in nineteen ‘chapters,’ but they can again be organized into overlaying themes of arguments, which is indeed what Perlmann has done in his translation of the Ifḥam. The themes as we find them are:
- A return to abrogation
- Jesus and Muḥammad
- The claim to being the chosen people
- The Bible
- Composition of the Bible
- Jews on Islam
- Objectionable aspects of Jewish law; levirate, segregation
- Rabbanites & Karaites
- Epilogue: Sins and follies of the Jews
What Samaw’el attempts to do is to prove that in the Jewish tradition there is found examples on abrogation, and by forcing the Jews to accept that he (feels he) proves that the Torah might have been abrogated.
With that established he argues for the status of Jesus and Muḥammad, then for why the Jews are not chosen, for then to focus on the Bible and its composition, Jewish reflection on Islam, a discussion on Halachah (Jewish religious law) and issues within the law, moving on to the particulars of the Rabbanites and the Karaites, for then finishing off with the sins and wrongdoings of the Jews as a whole.
I will be presenting one part on its own, not going through all of the arguments, since that probably will be rather overwhelming in just one post. When I am done with the presentation of his arguments I will attempt to present you for the various Jewish responses, and then finally try to give some responses myself, some of his arguments being rather time-bound and having lost their actuality today.
The first focus is on his arguments for abrogation.
Samaw’el first introduces us for his base of arguments, which – he claims – is meant to convince the Jews of the principle of naskh, abrogation, based on their own scriptures and methods.
His way of arguing is based on a proposal, which then can either be accepted or denied. Here it is the question on whether there was a divine law before the giving of the Torah or not.
If they, the Jews, deny this, then they will also deny – according to Samaw’el – that God gave Noah a commandment, namely the one against murder (Genesis 9:6). Besides this point, he also points out the commandment to Abraham to circumcise the male children at the eight day.
Should the Jew admit that, yes, God did give divine commandments before the giving of the Torah, then he will ask them, whether it didn’t add something to those earlier precepts. In case the Jews answer that it (the Torah) didn’t add anything then it is meaningless, since it does not contain anything besides the already given legislation, and thus it cannot be of divine origin. But, he states, that would be the same as to not believe.
In case the Jews says that, yes, it did add something new, then – Samaw’el asks – does this new addition not prohibit what has was allowed before? In case they deny this, then they are found in fault, since the Torah added the prohibition against working on Shabbat, something which before the giving of the Torah was permitted. And furthermore, all addition in law has as its purpose to either allow what was prohibited before or prohibit what before was allowed. These examples, he states, are clear examples on Naskh, abrogation.
One could argue, he maintains, that one does not first forbid something, in order for later to allow it, since that would be like allowing the same thing that one forbids, and that would go against the nature of God (described as “the wise one”). But since He is commanding two things at two different points of time, this will not be a problem, only if it happened at the same time.
Then the case might be forwarded that the Torah forbade what had been forbidden, but not the other way around. That is, it is true that there was a law before, and that law prohibited murder, but murder had not since been allowed (relating to his two examples), but earlier it had been allowed to work on Shabbat, but after the giving of the Torah that became prohibited.
The obvious problem for Samaw’el here, because he does accept that this is a legitimate claim, is that if one holds that that is the case, then the Quran can only prohibit what earlier was allowed, but not allow what earlier was prohibited. This is based on the rationale that one who abstains from what is permitted is not per ce a violator, but one who does what he has been forbidden certainly is a violator, and since the Quran allow working on Shabbat, then that would be an encouragement to violate a commandment.
Samaw’el attempts to answer this by pointing out that something does not necessarily need to be prohibited for good. Rather, he explains, since working on Shabbat had been permitted for Abraham and other before him, and then prohibited, then it certainly is possible that it again would be allowed.
The reasoning behind Samaw’el’s argument here is that either a law is imposed for all times, having God being displeased with it in total, or it is not imposed for all time, and God only displeased for a certain amount of time, and since working on Shabbat was not prohibited for all time, then it holds that it is possible that it can be changed later.
Of course Samaw’el concludes from this that if a divine messenger, Muḥammad, would bring miracles and prove to be a prophet, then it would be possible that he would change what before was deemed illegal. Especially when – according to Samaw’el – a man brings clear proof that he is a prophet, then one should heed his message, which would be of reason, contrary the precept found in Judaism, such as cleansing impurities with ashes of the heifer, which in turn also would make the Kohen burning the heifer unclean (Numbers 19).
Since God is above any imperfection and criticism, and his messenger necessarily may speak a true message, then it stands for God to be able to change what He earlier has commanded, and Muḥammad, who is send by God, should be heeded, if one will not deviate from the truth.
Having dealt with the first approach to proving that abrogation also is part of the Jewish tradition, Samaw’el now continues with the next, relating to the matter of the red heifer, the cow having to be burned in order to use its ashes for purification, a process which would leave the one performing the burning impure himself. The problem, according to Samaw’el, is that since that process is needed in order to purify a person who has been in contact with a corpse, it is still not needed in order to allow the person to pray or carry holy texts, according to the Rabbinic tradition.
If this is explained with the fact that the ritual of the heifer cannot be done today, from the lack of the Temple, then Samaw’el’s answer – again in form of a new question – is whether the inability to perform the act also dispense it. Here, again, two answers are possible, either that yes, it does dispense it, which, he maintains, proves abrogation by reason of present circumstances, and thus proves his point, that laws and rules can be abrogated. In case that they answer in the negative, they basically admit that they are in a continuous state of impurity, so far as they have been in contact with a corpse, a tomb or the like. This is a build up for his coming point, being triggered by the strictness surrounding the menstruation of the woman, leading to a period on approximately two weeks, having the consequences that a man cannot touch her in that period, not even her husband, who has to sleep separate from her. The answer to this might be that it is a commandment from the Torah, which means that it has to be interpreted in its most strict sense, but if that is the case, then the case of a man having been in contact with a corpse has to be even more strict, since it demands the sacrifice and burning of an animal in order to purify him. And furthermore, should a non-Jewish woman being menstruating she won’t be considered impure, her touch not being shunned on the same level of that of a menstruating Jewish woman, even though nothing is mentioned about this in the Torah. And this leads to yet another example on abrogation.
The Jews might argue in return, that this is not based on the Scriptural text alone, but on the system of laws which constitutes the Oral Tradition. This, Samaw’el explains, is leading to the question of the Jewish sages, whether they are reaching their conclusions on human reasoning or whether they are divine tradition. As is the case, it would be stated that this is surely tradition going all the way back to Moses, which then will lead to Samaw’el asking how the sages then can reach different conclusions, since that would leave with a tradition which each of the disagrees will claim goes back to Sinai. This is contradictory in the eyes of Samaw’el, being an example on the Jews baseness, crediting God with contradictory commandments.
Samaw’el is aware that there is a principle of following the majority, when it comes to halachic decisions in Judaism, though he considers this to be the giving up of one of the sages’ tradition, or at least as consider the possibility of an error in his tradition, which would lead to the conclusion that he (the sage in question) cannot be trusted anymore, or – as a last consort – that the sages have agreed that one decision abrogates the other. And since there are many examples on sages being the minority in some cases, they are the majority and followed in others, this would have to lead to the acceptance of abrogation yet again.
His third argument over abrogation is focused on the Jewish prayers. This is introduced with the question on prayers and fasts, whether the prayers that the Jews are praying at his time (Samaw’el) are the same as those of Moses.
He presents us for a number of examples from the ‘Amidah, the main prayer prayed thrice daily, asking if any of these examples were prayed by Moses and the Jews of his time. The examples mentioned by Samaw’el of course cannot be said by Moses, since they mention the ingathering from the exile from the four corners of the earth, and the rebuilding of Jerusalem. Besides those two examples he also mentions the fast of Gedalyah, the fast of Tisha b’Av and others examples, which only can have been established long after Moses lived. If these examples still leave the Jews denying that there are talk about any abrogation, he will point to Deuteronomy 13:1 “Everything I command you that you shall be careful to do it. You shall neither add to it, nor subtract from it.”
His final argument on abrogation regards the first-born, who according to Exodus 13:2 is sanctified for God, but – Samaw’el points out – it was later changed so the Levites took the place of the first-borns of Israel, since they joined Moses when he came down from Mount Sinai and witnessed the worshiping of the gold-calf.
Based on all his arguments presented here, he conclude that the Jews cannot deny these arguments, leaving them only with admitting either that the Torah has been altered or that these are indeed proofs of abrogation.
 It is the same reasoning that can be found in medieval argument for God’s eternity. Nothing can be eternal if it has a beginning or an end.