X: Medical research on animals should not be reduced in response to a concern for animals, because results of such research serve to avert human suffering  In such research a trade-off between human and animal welfare is always inevitable, but we should give greater weight to human welfare
Y: With technology that is currently available, much of the research presently performed on animals could instead be done with computer modeling or human subjects without causing any suffering
contradicts a premise on which X's argument relies