(For other posts in this series, see here.)
The theory of evolution says that we are all connected in the tree of life. So humans are not only related to apes and other animals, we are also related to plants and even to the ‘lowly’ fungi. But no one is arguing that therefore we should stop eating vegetables too.
Clearly to survive we have to draw at least some lines as to what species we include within our moral community and what species we exclude. Such lines are necessarily arbitrary but need not be without some justification.
If we are going to use suffering as the measure of whether we are justified in killing and eating animals, then that implies that sentience is a key marker. But what level of sentience? Peter Singer and other animal rights philosophers argue that some level of sophistication of the nervous system is necessary to include the species within our moral compass. They draw the line at the nervous system of scallops, so that anything with an equal or more primitive nervous system than a scallop can be eaten. [Read more…]