Which one of the 13 principles does it contradict?
Anyone who is familiar with Ethical Veganism knows that at the root of the movement is the rejection of the “commodity status” of animals- the idea that animals can be owned or used for human purposes. Vegans consider man,too, to be an animal, and as one species in the animal kingdom, man has no right to "exploit other animals" for his own needs. This idea that man is just another animal is not a philosophy that just happened to take root amongst the masses. It is promoted in the highest echelons of Academia, and at the most prestigious universities in the country. And there is a payoff for those preaching this philosophy; the corollary of this idea is that man has no true bechirah, no free will; man is just another animal, albeit a smarter animal, yet guided by the same instincts that predetermine his choices in life, just like all animals.Therefore there is no moral imperative for one to work on himself, no absolute good and evil, just the predetermined path in life that mans animal instincts lead him along.
Yet the Torah tells us that man is not just another animal. Man alone has bechira, and the entire universe was created for man to exercise his bechira, his free will. Animals were created to provide food, clothing, and labor for man, the purpose of creation. And the Torah did not limit the use of animals to Avrohom, Yitchak, and Yaakov, and our other holy forefathers, although they certainly were able to elevate the animal to a lofty purpose, in their use of animals to further their serving Hashem on their exalted level. The Torah obligates every simple Jew to wear leather Tefillin on his arm, wool tzitzis on his body, place a mezuzah on his door, and read from a Torah made from animal hide. this is diametrically opposed to the adherents to the ethical veganism philosophy, who place man and beast on equal footing; the movement is antithetical to the core principles of the Torah.