In my humble opinion this view is perhaps not in the best tradition of the Halakhah. For the issue involved here is that of when the benediction ("Who has sanctified us with His commandments, and has commanded us to recite the Hallel") is said, rather than the recitation of the Hallel itself and the circumstances that led to it.
We recite the general benediction including the formula "Who has sanctified (asher kideshanu)" before the performance of many mitzvot, such as the washing of the hands, putting on the tallit and tefillin, eating bitters at the Seder, sitting in the Sukkah, and lighting the Chanukkah candles. Some of these commandments are biblical in origin whilst others are the result of rabbinic enactment (takkanah).
It is with regard to the lighting of the Chanukkah candles, a mitzvah established by takkanah, that the Talmud (Shabbat 23a), seeks a source for the equality of rabbinical with biblical commandments.
How, the Talmud asks, can we say ve’tzivanu ("and He commanded us") as part of the benediction, when the entire commandment is only a rabbinic decree, and not part of the biblical revelation? Two answers are given. The first of these, offered by R Ivya, is accepted by Maimonides (Hil. Berakhot 11:3). R. Ivya cites Deuteronomy 17:11,". . . thou shalt not turn aside from the sentence which 'they shall declare unto thee, to the right hand, nor to the left" which commands us to obey our halakhic authorities in each generation and not to deviate from their commandments. Furthermore, this passage, in Deuteronomy 17, is preceded by "unto the judge that shall be in those days" (17:9), upon which the Sifre comments (as quoted by Rashi), "even if the halakhic authority in your generation is inferior to his predecessors, you are obliged to obey him!" Thus, a takkanah by the rabbis of our generation has the authority of the word of God as revealed in the Bible. In the same vein, the Talmud tells us (R.H. 25b) that Gideon in his generation is likened unto Moses in his generation, Samson to Aaron, and Jephtah to Samuel. One has to go no farther for an interpretation of the law than the contemporary authority. Maimonides is even more emphatic (Hil. Mamrim 2:1), saying that "You have no farther to go than the court of your generation."
There is a vast halakhic literature on the equality of takkanah with the word of God. The general attitude is best expressed by Nachmanides in his commentary on Exodus 21:6, where he explains that the word "God" is often used in the Torah to designate the halakhic authorities, because God sanctions their decrees and their decisions, and it may be considered as if He Himself decided them. (See, too, Sefer ha-Chinukh, no.496.) Consequently, when the rabbis in our generation tell us to read the Hallel on Yom ha-Atzmaut, it is as if God Himself commanded it.
However, there are specific sources regarding the benediction over the Hallel that deserve special study. We shall now proceed to examine them.
In Berakhot (14a) the Tosafot state that on Rosh Chodesh it is a minhag (custom) to read the Hallel. The opinion Machzor Vitri is quoted to the effect that since it is only a minhag, we do not recite the benediction. The point is further made that the benediction on a minhag is not regarded as a blessing in vain (berakhah le'vatalah), just as women may pronounce the blessing over mitzvot from whose observance they are exempt such as Lulav, or even tefillin.
In Sukkah (44b), the Tosafot discuss the problem of those benedictions pronounced on the second days of Yom Tov, which are observed only in the Diaspora. These days are observed only as a matter of minhag. They declare that ve’tzivanu cannot be recited, there being no specific "commandment" to observe them. They also point out that the sounding of the Shofar on the second day of Rosh Hashanah is a takkanah, thus requiring a ve’tzivanu blessing. Rabbenu Tam maintains that the complete Hallel is recited with the prior benediction when the redemption occurs to the entire people of Israel. Rabbenu Chanannel remarks, at the conclusion of this Tosafot passage, that if redemption occurs to a group, then that group recites Hallel without a benediction. This statement of Rabbenu Chanannel is somewhat out of context in Sukkah, but its relevance becomes more evident when we consider a statement by Tosafot in Taanit (28b), and again in Arakhin (10a), where Rabbenu Tam's opinion is cited as affirming the benediction on a minhag, such as the benediction before Hallel on Rosh Chodesh.
There are thus five cases, according to the Tosafists, in which the ve'tzivanu blessing is to be considered:
1. A mitzvah of the Torah, such as Tefillin, Lulav or Tzitzit, observed under circumstances prescribed by the Torah.
2. Observance of a mitzvah of the Torah in circumstances not prescribed by the Torah, e.g. women performing the mitzvah of Lulav (which is not obligatory upon them).
3. Observance of a mitzvah ordained by rabbinical edict (Takkanat Hakhamim), such as reciting the Hallel when this is prescribed by the Rabbis, for example on Chanukkah.
4. Observance of a mitzvah (ordained by rabbinical edict) as a minhag, in circumstances not prescribed by the Rabbis, which has been universally accepted, such as the recitation of the Hallel on Rosh Chodesh.
5. Observance of a rabbinical commandment in optional circumstances on a local or individual basis, such as a congregation saying the Hallel on a day they were delivered from a calamity.
There is no question at all that we recite the ve'tzivanu blessing in cases 1, 2, and 3. The question arises in case 4. Here Rabbenu Tam maintains that a benediction is pronounced, while the other Tosafists disagree. In case number 5, where local observance is pursued, Rabbenu Tam concedes that a benediction is not pronounced.
The issue under consideration is this: does a mitzvah ordained by rabbinical edict still remain a mitzvah when it is observed outside of its prescribed limits? Rabbenu Tam says yes, and though Rashi and other Tosafists disagree, halakhic practice has followed Rabbenu Tam who is supported by such decisors as the Rama, Mordecai, and Ashri (Shulchan Arukh, Orach Chayyim 422:2).
Note that not once in reference to the benediction has there been any mention of the nature of the circumstances contributing to the universal acceptance of a rabbinical mitzvah (in unprescribed circumstances). It is rather the performance of the mitzvah and the definition of its limits which are important.
The current objection to a benediction before Hallel on Yom ha’Atzmaut is that an "overt" or supernatural miracle is not associated with Israel's independence. The State of Israel, it is argued, is only a first step in the redemption; a genuine geulah has not yet been achieved. Assuming all this to be true, it is still irrelevant. For we have conclusively shown that once the Hallel is universally recited, irrespective of why it has been accepted, it requires a benediction. This is certainly true of the Hallel on Yom ha’Atzmaut even it we were to consider the Hallel reading then a universal minhag. Although the Hallel reading on Yom ha’Atzmaut is not a takanah of a Sanhedrin, it has most certainly received the sanction of our leading halakhic authorities, which is the equivalent of a takkanah (in view of Deuteronomy 17:9).
The basis of the argument concerning the nature of the miracle of Yom ha’Atzmaut is attributed to Rashes remarks concerning when the Hallel is to be said (Pesachim ll7a). He states that if, God forbid, a calamity befall Israel, we are to recite the Hallel upon our subsequent redemption, as is the case on Chanukkah. The statement "as on Chanukkah" is construed by some authorities to mean a miracle such as occurred Chanukkah, conforming to Rashi's commentary on Shabbat 21b: "for which miracle was it [Chanukkah] instituted?" However, these arguments seem to be taking Rashi out of context in view of what Rashi has stated in his commentary on the Siddur in connection with reciting the Hallel on Rosh Chodesh: "I do not recite a benediction on it, either when praying alone or with the congregation, because it is only a custom, and a custom requires no benediction . . . but I do recite the concluding benediction melekh mehullal ba-tishbachot." The implication is, clearly, that Rashi's objection to the benediction is based upon his agreement with the Tosafot, and not because of any reasons governing the reading of the Hallel itself.
My personal opinion is that Yom ha’Atzmaut is on par with Chanukkah, and it is improper to judge the value of a holiday on the basis of the miracles performed on that day. My opinion is based on Maimonides’ comments on the nature of miracles (Hil. Yesodei Torah 8:1): "The Children of Israel did not believe in Moses because of the miracles he performed, because he who believes only on the grounds of miracles possesses a baseness in his heart that perhaps the miracle is accomplished by magic or sorcery. Rather, all the miracles that Moses performed in the desert were performed because of necessity and not as proof of prophecy. It was necessary to drown the Egyptians, so the sea split and they sank in it; we required food, he brought Manna down on us; they were thirsty, he smote the rock, etc." Similarly, I think that if there would have been enough oil, there would not have occurred a miracle of Chanukkah. The miracle came about because of necessity. If there were no miracle associated with Chanukkah we would still recite the Hallel today because of our redemption at that time. If there would have been a necessity for an overt miracle during Israel’s War of Independence, I have no doubt that God could have and would have wrought it.
The article by Marvin S. Antelman presents a competent analysis regarding the pronouncing of the benedict on asher kideshanu. Nevertheless, I cannot agree with his conclusion that a benediction is to be pronounced before Hallel on Yom ha’Atzmaut.
Mr. Antelman states that the fact that the miracle of Yom ha’Atzmaut was not overt is irrelevant, "For we have conclusively shown that once the Hallel is universally recited irrespective of why it has been accepted, it requires a benediction" (italics mine). I must disagree with the statement that there is such a thing as a minhag to say the Hallel as such. In my article I have shown that the recitation of Hallel falls into two categories: 1) Hallel on Yom Tov recited as Shirah, and 2) Hallel on Chanukkah recited over an "overt" miracle. There is no Hallel without one or the other. Essentially Hallel consists of chapters 113-118 of the Book of Psalms, yet the mere recitation of these six chapters does not constitute Hallel any more than the recitation of any other six chapters in the Book of Psalms.
Thus, there are Jews who divide the Psalms into thirty portions, reciting one portion every day of the month. On the twenty-fourth day of the month, they recite psalms 113 through 118. Does that mean that they recite Hallel on the twenty-fourth day of every month?
It is also customary to recite the entire Book of Psalms on Rosh Hashanah. Does that mean that we recite the Hallel Rosh Hashanah, contradicting the talmudic statement that no Hallel is to be said on Rosh Hashanah?
Thus if we consider the miracle of Yom ha’Atzmaut insufficient reason to say the Hallel, there can be no minhag to recite Hallel as such, but merely to recite certain Psalms.
As to the minhag to recite Half Hallel on Rosh Chodesh, there the situation is different. Rabbi J. B. Soloveitchik in his Yahrzeit Sheur on 4 Tevet, 5717, explained the statement in Arakhin 10b, Rosh Chodesh, which is called moed, should require the recitation of Hallel. There is no prohibition to work on this day" as follows: A festival such as Passover possesses kedushat ha'yom (sanctity) because of: a) Musaf the additional-sacrifice offered in the Temple; b) Prohibition of work; c) Obligation to make the pilgrimage to Jerusalem; d) Special mitzvot such as matzah. All festivals have one or more of these qualities. Rosh Chodesh, however, is distinguished only by musaf and is thus a festival in the Temple only, where Hallel was recited as din (law) not minhag. The minhag to recite Hallel on Rosh Chodesh consists in extending the kedushat ha-yom from the Temple to Jewish communities outside its precincts, even as the minhag of Yom Tov Sheni Shel Galuyot means that we extend kedushat ha-yom to the second day, and does not mean that there is one minhag to eat matzah the second night of Passover, another to eat maror, a third to drink four cups of wine, etc.
As to the argument that there was no overt miracle because it was not needed, I do not believe that makes any difference halakhically. The reason given why no such miracle occurred is a matter of metaphysics. I would be rather inclined to accept the view that such a miracle did not take place because our generation is not worthy of one.