"I will try to express myself in some mode of life or art as freely as I can and as wholly as I can, using for my defense the only arms I allow myself to use -- silence, exile, and cunning." -- James Joyce
Rape occurs in many animals, therefore…
Would anyone use this as an argument that human rape is therefore morally unproblematic?
If not, then there is no reason to think other arguments of the same form are valid either.