A rabbi with whom I was discussing this topic was very concerned when I mentioned this point. "How can you say that the Torah and Chazal do not address this vital issue?" he protested. "You can't say that determining death is something that is just not in the mesorah!"
Well, it won't be the first time that this has happened. And greater people than me have pointed it out.
Rabbi Nachman Cohen, chairman of the Board of the Association of Orthodox Jewish Scientists, told me that Dr. Abraham S. Abrahams would often tell at AOJS conferences how he had once consulted Rav Shlomo Zalman Auerbach ztz"l about the halachos relating to cloning. "I'm sorry," said Rav Shlomo Zalman, "but the Torah just doesn't say anything about it." (see too this post.)
That's why I argued that in order to derive the Torah perspective on determining death, we need to look instead at traditional, albeit non-halachic, sources on what human life and identity actually means, rather than looking to make inferences about determining death from halachic rulings (which just can't be done). My friend Rabbi Dr. Eddie Reichman pointed out to me that others have made this claim in similar situations. Rabbi Ezra Bick, in an article in Tradition, discusses a critical question with IVF: is it the egg donor or the birth mother who is halachically considered to be the parent? As with determining death, there are those who seek to deduce the answer from various statements in the Gemara. And as with determining death, Rabbi Bick demonstrates that such inferences are unwarranted, and that the Gemara really does not contain any halachos from which we can resolve this novel, modern situation. He further points out that any attempt to derive the halachah from Chazal is hindered by the problem that Chazal did not realize that a baby develops from a woman's ova (they thought that it develops from the sperm). Instead, Rabbi Bick proposes, we need to draw guidance for a halachic conclusion from the general trend of non-halachic statements in Chazal:
Returning to the major question of the halakhic model of conception, is there any halakhic source sufficient to resolve it? The answer is no. I propose instead to attempt to discover the general conceptual framework of the Sages concerning conception...
The launching point for what I have done is the conclusion that no normal halakhic proof exists for deciding the question of maternity. Having accepted that as a starting point, I posited that it would be valid to use an entirely different method in order to reach a conclusion.
What does one do when there are no sources for a halakhic answer to a pressing question? Our usual answer is "hafokh ba, hafokh ba" - keep looking! There is always a source. But are there not dozens of halakhot and legal principles in the Talmud which have no apparent scriptural source? Are we to assume that there must have been a source, or that the Sages of the Talmud were granted a unique (prophetic?) ability to originate halakha? One would be hard-pressed to find a source for such a position. There are a limited number of specific instances where the Tosafot, for example, state that a particular talmudic halakha is based presumably on some scriptural text, although unknown. That is because the halakha in question strikes Tosafot as not being particularly self- evident, or even logical. In numerous other cases, however, the only source of a halakha is Reason, although it does not represent, strictly speaking, the only logical possibility. The Sages have certain conceptions of law and understanding of various concepts which underlay halakhic conclusions. Our topic is in fact a perfect example. If it is true, as R. Bleich claims, that the Sages consider birth to be the determinant of motherhood, what is their source? If sperm donation determines paternity without intercourse, or vice-versa (the question of paternity in artificial insemination), what are the (pre-Talmudic) sources?
Halakha is riddled with concepts that reflect the assumed conception of the Talmudic Sages on a particular topic. In our halakhic investigations, we attempt to base all our conclusions on the determination of the Talmudic concepts, because we accept implicitly the legal formulations of the Sages. Rarely does a contemporary halakhic discussion investigate the sources of Talmudic concepts. It is simply accepted that certain basic assumptions underlie many halakhic formulations, and we accept those assumptions if they are evinced in Talmudic halakha.
What then do we do if there is no Talmudic halakha relevant to the assumptions needed for a decision in our question? It appears to me that we are justified in trying to determine the Talmudic assumptions, the base conceptions of the Talmudic world-view, from other sources. This is not the same as the oft-rejected aggadic source for halakhic conclusions. To derive a halakha from a single aggadic source is misleading, as we cannot be sure what the intent or precise factual meaning of the aggada is. To use the aggada to determine a general approach of the Sages to a question, in order to determine what halakha must necessarily arise from that approach, is, although risky and lacking the certitude we are accustomed to expect in halakhic discourse, in principle as valid as what the Sages would have done in the first place had they faced the question we are facing today. Were there to exist absolutely no Talmudic guidance for our question, neither in halakhic or aggadic sources, in principle we would have to formulate for ourselves the proper way to understand the necessary concepts, in the same way that the Talmudic scholars did. I cannot imagine any serious Torah scholar being happy with such a situation; we depend upon direct Talmudic sources as a fish depends on water. Nonetheless, I believe it is a valid way to derive halakha; indeed, it is one of the bases for Talmudic halakha itself.
...If it is fair to derive philosophical concepts from the halakha, it must be because these underlying concepts are basic to the world-view of Torah and not only halakha in the strictly legal sense. There is a stricter level of logical rigor required in halakhic definition than in aggadic definition; hence it is risky going from less-well defined aggada to the strict domain of halakha, but it is not excluded in principle. If the Halakha has a world-view and a conceptual basis, which is the conceptual framework of the Sages, there may be cases where there is no other way to determine that conceptual basis other than to examine the wider framework as expressed in aggada.
This is completely different from trying to derive the halakha directly from an aggadic comment or story. Since the purpose of the aggada is not to decide halakha, the halakhic conclusion may be totally irrelevant and not necessarily accurate. However, the conceptual conclusion is not incidental to the aggada but directly implied by it, and if the same conceptual conclusion has halakhic ramifications, they are in principle valid. There are two problems here, first in determining the conceptual conclusion with the desired degree of precision, and then determining the halakhic ramification, which necessitates a further degree of specificity not always possible for philosophic concepts. The conclusion will be almost unavoidably tentative. In cases where direct legal analogy or derivation is non-existent, there may be no choice.
One of the basic endeavors of contemporary talmudic research is the attempt to uncover the conceptual models of halakhic conclusions. This consists not only in proposing a svara for a given halakha, but in formulating the second~layer conceptual assumption of the first-level svara. Unless this is a merely intellectual exercise, it implies that the underlying conceptual model has halakhic validity; i.e., that further halakhic conclusions may be derived from it. Students of modern talmudists - especially those of the Rav, Rabbi Joseph B. Soloveitchik - are familiar with this process; it is a daily exercise in advanced talmudic reasoning.
This then is our first assumption, that the halakha is based on conceptual models. Our second assumption is that the conceptual model is not in itself a halakhic statement. Hence, it is in principle not limited in operation only to the realm of halakha. One consequence of this assumption is that we could, on the basis of conceptions derived from the halakha, formulate a proper Jewish philosophy; i.e., derive aggada from the halakha. This, of course, was the basis for most of the Rav's philosophic endeavors, and in fact is, in his opinion, the most, perhaps only, valid way to discover the philosophy of Judaism. A second consequence is that in principle it would be possible to derive the conceptual model from the aggada. If the conceptual framework has applications in the halakha and the aggada, it may be derived, at least in principle, from either. Hence, eventually, in this way, we will reach halakhic conclusions based ultimately on aggadic source material.
- Rabbi Ezra Bick, "Ovum Donations: A Rabbinic Conceptual Model of Maternity," Tradition 28:1 (1993) pp. 28-45.
I believe that determining death is the exact same situation. Like IVF maternity determination, there is no halachic source sufficient to resolve it. Like IVF maternity determination, attempts to derive the halachah from Chazal are hindered by their mistaken beliefs about physiology (in IVF, with Chazal's lack of awareness of the existence of the ova, and in the case of determining the significance of the functioning of bodily systems, with Chazal's lack of awareness of the role of these systems). But there is a general trend of non-halachic statements in the Rishonim - from which we can derive a framework of values that can be translated to halachah - which is that human life (and the human soul) is defined by the mind. I already demonstrated how Ramban clearly presents this view, and I shall also demonstrate it to be found in other Rishonim.