Question: Must one be a vegetarian according to Maran Ha-Rav Kook?
Answer: Maran Ha-Rav Kook wrote in "Kovetz Tzimchonut Ve-Ha-Shalom" – "Vegetarianism and Peace" – that vegetarianism is a future vision. Its importance is real, but not for today. Why not? Because it is impossible to skip stages (in human development). Some vegetarians explain that they do not eat meat in order to show compassion to animals. That is certainly important, but we first need to show compassion towards human beings, and we have not finished all of our obligations in this realm. Once we succeed in being merciful and righteous towards human beings, we will move on to animals. We cannot skip stages. We are not criticizing those who are vegetarians. If a person wants to be a vegetarian, he may do so, but it is impossible to define it as a mitzvah or even as a stringency. Someone once asked me: I am a vegetarian and I have decided to stop. Do I need a "Hatarat Nedarim" (annulment of vows), since someone who performs a proper custom a few times and wants to stop must perform a "Hatarat Nedarim"? I said that there is no need for a "Hatarat Nedarim," since vegetarianism is not a mitzvah or stringency. It is a good, compassionate, and a proper character trait for one who wishes, but it is before its time. An individual who desires to be a vegetarian is fine, but this cannot be – as Maran Ha-Rav Kook refers to it – a communal practice. Maran Ha-Rav Kook also warns in the same article that vegetarianism can actually be a hijacking of the feelings of compassion. This means that sometimes there are people who are cruel to other people, but because their Divine souls cannot bear this cruelty, and need to be pacified, they say: we will be vegetarians and be compassionate to animals. In fact, there were Nazis in the concentration camps who were vegetarians, and some evrn say that Hitler himself was a vegetarian!
Maran Ha-Rav Kook ate meat, as did our Rabbi, Ha-Rav Tzvi Yehudah. Among the letters of Maran Ha-Rav Kook is one he wrote to our Rabbi, when he (our Rabbi) was young and not eating meat. Rav Kook asked him: Why aren't you eating meat? You need to eat meat. It is not our level to refrain from doing so. You know that there are many cruel people in the world and many vegetarians who are cruel. Maran Ha-Rav further wrote: A Torah scholar, along with other things, needs to know how to slaughter animals. There are certainly Torah scholars who do not know how to slaughter, but it is good and proper. Please learn to slaughter (Igrot Re'eiyah vol. 3, letter 780). And in another letter (ibid. letter 784): Did you learn to slaughter? And another letter (ibid. letter 799): So, are you learning to slaughter? And finally, a letter (ibid. 839): I am happy that you learned to slaughter. Now that you learned, you need to do so. So, did you slaughter yet (see letters 852, 853 and 860)? Maran Ha-Rav Kook pressured our Rabbi so that he did not adopt the ideology that it is forbidden to slaughter or eat animals.
Not eating meat is a future vision. How do we reach this future? Slowly, in stages, through all sorts of preparatory Halachot which teach us that we need to respect animals, refrain from being cruel to animals, not to cause undue pain to animals, etc.