Several months ago, a person asserted to me that they thought chickens were unclean. For whatever reason, I chose to be open-minded about the assertion and go into the text.
As background information, the way that the rabbis have determined which birds they consider to be clean is largely based upon the practices of various Jewish groups throughout history. While this is understandable, this assessment alone cannot justify a practice in accordance with the Torah, as there are a multitude of things that have been practiced incorrectly by those who presume observance throughout history and even today. Need I bring up the whole reason for the exile, or need I bring up all of the problems with the rabbinic traditions?
When getting into the text, there is a noteworthy problem for us today. That is, neither Leviticus 11 nor Deuteronomy 14 list specifications as to how to discern which flying things are prohibited, but instead they provide a list of prohibited birds. This is distinct from how beasts, fish, and insects are dealt with, in that those groupings all have descriptions regarding discerning their status (such as "fins and scales" for clean fish).
If one has the foundation of their studies in conventional translations (especially when focusing on a single translation), one might assume that the identification of all of these different flying things are already known. Indeed, some of the animals specified do appear elsewhere in the TNK, such as nesher, which is fairly definitively "vulture" or "eagle" based upon its other uses and their contexts in the TNK. However, many of the words for different birds appear exclusively in Leviticus 11 and/or Deuteronomy 14 alone, with no other obvious corollaries.
One might assume that identification can be arrived at through the etymologies of the species names. The first problem with that is not all of them have obvious root words to them. The second problem is that even when we can assume a root form, we cannot always make a reasonable assumption as to what that description refers to. For example, ahzniyah seems likely to be related to the word oz, meaning "strength", but can we readily assume which bird is the "strong bird"? Likewise, chasiydah is related to chasiyd, which approximates to "pious", but how do we know which bird is the "pious bird"? We can make presumptions, but these presumptions may or may not be accurate. As a more relatable example, possibly, in English, there is a mammal (actually more than one) whose name is etymologically is formed from words meaning "the brown one". We could make a guess as to what this animal could refer to. We might guess correctly, or we might not. This is the problem with not having any sort of context to check it against.
When I presented a similar case to someone I know, a response was that chickens/etc would not seem to match any of the other unclean flying things in the text, so therefore they would be clean. There are multiple points against this that should already be apparent: First, we do not know what the ancient Hebrew word for "chicken" even was, so of course we would not identify any of the unclean birds as chickens. Second, we do not know what all (or even very many, for that matter) of the prohibited birds are in the text, so we cannot make any sweeping assessment regarding what would seem to fit. If we knew what all of the birds were with certainty, then we could make assessments through the comparison with that known list, but the fact is such that this knowledge does not reasonably seem to be available. Third, which is related to the second, filtering our understanding through what we learned from a conventional English translation regarding clean and unclean birds is not going to necessarily coincide with the actual Hebrew command. That is, if we "learned" from the English or otherwise presumed accuracy to certain dictionaries, then what we arrive at in terms of what "seems right" is not going to be inherently according to the Hebrew text. It is instead going to be what "seems right" according to what we read previously in the English, which was translated presumptuously. While I would certainly not assert that all English translations are inherently flawed in every single verse, as some seem to argue, it is certain that conventional translations and many dictionaries are willing to make complete guesses in regard to these identifications. They would rather have any answer, even if it is a guess, than no answer. Some of these guesses do not even coincide with other passages in the TNK. They are simply guesses. It would not seem reasonable to argue that our understanding of that passage dictates that chickens/etc are clean, because that understanding was likely based upon the guesses of those translators. Our understanding regarding the Hebrew is lacking, which is the whole point of this.
The Septuagint could possibly be looked to in helping to understand these passages and the species identifications. Indeed, some of the birds mentioned are translatable in Greek, such as the latter two birds of Leviticus 11:18, which read "pelican" and "swan". However, even if we rely on the Greek, several of the species names are still not readily translated. This basically leads us back to the same situation we were in before.
Ultimately, our current understanding of the bird prohibitions is lacking. Without there being more sources for context, or otherwise some sort of verifiable prophetic revelation, it would not seem reasonable to claim full knowledge of the distinction between clean and unclean flying things.
In regard to chickens and other galliformes, like turkeys, I do not think it reasonable to simply presume that they are clean. While it is possible that chickens/turkeys/etc are clean, we cannot say this definitively with the information we currently have. Therefore, I do not eat chicken, chicken eggs, or derived products because I do not know that chickens would be clean with certainty. The Torah has no obligation to follow modern classification systems of birds, so simply because quail and chickens are both considered galliformes, and quail is presumed to be permitted (update: the LXX does not necessarily support the quail claim, see here), this does not mean that chickens would not be unclean.
I would suggest caution as well, and giving concern and regard to the information presented. Is it worth things not being "as easy" in order to be cautious regarding obedience? I would say yes.
(By the way, in case you were still wondering, the answer to "the brown one" is "beaver" or "bear". This is just an example how impractical it is to simply use a species name's etymology to identify it. While an etymology is useful, without having any context, a certain identification is not likely to be arrived at.)
(From prior posting on Gr. 6/19/14, updated Gr. 7/9/15)
An updated posting is available here: Unclean Birds Part 2
