In the previous post, I addressed Rabbi J. David Bleich's astounding claim that there is "no scientific reason" to reject spontaneous generation. He presents this as part of an attempt to show that there are multiple legitimate ways of addressing Chazal's statements about spontaneous generation without saying that they made a mistake. Rabbi Bleich presents another approach, which he describes as personally finding more plausible: that Chazal did not consider microscopic eggs to be halachically significant.
But while it may well be reasonable for a Posek today to rule that microscopic eggs are not halachically significant, there is overwhelming evidence against the claim that this is what Chazal themselves actually meant (which is what Rabbi Bleich claims). Let us consider the evidence, and assess Rabbi Bleich's claim that "there is nothing contrived or anachronistic" in this explanation.
First of all, the words of the Talmud say nothing about the eggs being halachically insignificant due to their small size. It simply states that these insects do not reproduce sexually (and, in the case of fish-worms, that they develop from the flesh of the fish). While it is not impossible that this could be a shorthand reference for something else, the burden of proof is certainly upon those who would make such a claim. Especially since, in Talmudic times, the entire world believed that lice spontaneously generate, it is highly unreasonable to state that when the Sages spoke of lice as not reproducing sexually, they intended a different meaning entirely.
Second, such explanations are inconsistent with the views of the traditional Talmudic commentators. Rambam, Rashba, Ran, Tosafos and others all explain the Gemara to mean that lice spontaneously generate from sweat or dust. True, it is not impossible that they misunderstood the nature of the Talmud’s ruling — indeed, I post that this occurred with Rashi's explanation of the Talmud's reference to "dolfins" as referring to mermaids. Yet in the case of mermaids, there was compelling textual evidence that the Talmud was referring to dolphins instead; here, no such evidence exists. Furthermore, Rabbi Bleich appears to generally adopt the approach of faithfully adhering to the views of the Rishonim and Acharonim, not claiming that they all misunderstood the Gemara. Is it not inconsistent for him to claim here that the Rishonim and Acharonim all misunderstood the Gemara? And what reason is there to believe that they misunderstood it?
Third, the eggs of head lice and body lice are not in fact microscopic; they are quite easy to see with the eye. Rabbi Bleich writes that we must therefore say that the Gemara is talking about a different type of lice than those that we find today. This is immensely problematic from both a scientific and rabbinic perspective. From a scientific perspective, there is no reason to believe (and every reason not to believe) that the type of lice to afflict humans has changed, or that the lice eggs themselves have suddenly gotten much bigger. (I don't even think that the Goldstone boson provides evidence for it.) From a rabbinic perspective, the Rishonim and Acharonim, all the way through to the Chafetz Chaim, all presumed that the lice discussed by the Gemara are the same as those that we find today. When does Rabbi Bleich believe that they started to get it wrong?
Fourth, the Gemara discusses other cases of spontaneous generation, including the spontaneous generation of mice from dirt (Sanhedrin 91a), and of salamanders from fire (Chagigah 27a). Here, the actual process is not microscopic and there is no way of explaining it away in such a manner. Clearly, Chazal believed in spontaneous generation - as did the entire world in antiquity. I pointed this out in my letter to Tradition, making specific reference to mice and salamanders, but even though Rabbi Bleich wrote a nine thousand word response to a one thousand word letter (!), he did not respond to this.
Thus, the approach which Rabbi Bleich personally finds plausible, non-contrived and non-anachronistic, is in fact entirely implausible, utterly contrived, and wholly anachronistic, as well as going against all the Rishonim and Acharonim and clear evidence from other topics in the Gemara.
Following is another objection to Rabbi Bleich's point, but it is more involved and technical, so feel free to skip it.
In my letter, I pointed out that when challenged with the phrase "God sits and sustains from the horns of re’emim to the eggs of lice,” the Gemara rejects the idea that there are eggs of lice, and says that there is a species called "eggs of lice" (I explain the intent of this in Sacred Monsters). But if the Sages were not denying the existence of lice eggs, why do they reject the simple meaning of the statement that speaks about God sustaining the eggs of lice, and resort to difficult explanations instead? Let them simply state that although lice do hatch from eggs, these are too small to be halachically significant! It therefore seems that they did not consider this possibility.
Rabbi Bleich responds by claiming that the Gemara's objection in any case requires reinterpretation: "even if the thesis of spontaneous generation is understood literally, there is no reason to presume that kinim arise spontaneously as mature creatures (emphasis added). Certainly, divine providence would perforce necessarily extend even to spontaneously generated kinim. If so, God’s providence would indeed be necessary... How then, does the cited dictum negate the assertion that kinim are the product of spontaneous generation?" He proceeds to claim that the Gemara's objection must be that the providence over the development of the lice can be visually perceived, to which it responds that it can only perceived with a different creature called "eggs of lice."
Yet, again, this is forcing a reading into the Gemara for which there is no evidence and which, for this reason, no Rishon or Acharon ever proposed. Furthermore, Rabbi Bleich's question from the conventional understanding of the Gemara's objection appears baseless. He asks that even spontaneously generated lice would be generated as infants rather than adults, and thus surely it would be obvious that providential care is required. But the point of the Talmud's objection is that the phrase speaks of eggs of lice, which shows that lice are generated from eggs laid by other lice rather than from sweat.