&gt; There is a very clear and obvious distinction between the plant and animal kingdoms.<p>Sure, but whether the things which make up that distinction have particular ethical significance is a different question. And I have yet to see any definition of sentience for which both of the following are true:<p>(1) It does, in fact, apply to all animals and no plants, and<p>(2) Most people would agree that it has ethical significance.<p>In fact, I haven&#x27;t seen any definition of sentience for which even (1) alone is true.<p>&gt; Like I said, even if it were true that plants feel pain the same as animals, one would still be compelled to go vegan, since animals &quot;kill&quot; more plants than people do by eating them directly.<p>That seems to a apply a utilitarian standard of ethics, not the categorical one which is usually in arguing that veganism is an ethical compulsion (under the categorical ethics usually applied to argue for veganism, recognizing plants as sentient would make eating either inexcusable, even if it were a survival necessity.)<p>Once you accept that its a utilitarian matter, determining that something is ethically demanded requires agreeing to a particular ethical calculus -- a method of aggregating utilities and disutilities experienced by different participants. And there&#x27;s an infinite number of possible functions that can be used, and they can support any possible conclusion.