His position is that humans tend to rationalize their behavior and in doing so justify our mistreatment of certain groups of animals with no thought or concern for their inherent right to life; rather in our selfishness we too often have little regard for their well-being and quality of life. In order to substantiate his position he drew parallels through various instances of how humans either assume animals do not have emotions and can not feel pain or disregard the truth believing the human race is somehow entitled to do as they please in the name of science or sport.
Drawing first on the experimentation of insects in the furthering of science Suzuki concedes that somehow that may be justifiable, but then further builds on the examples of experimentations on mice, rats, guinea pigs and other rodents to further both the medical and behavioral sciences and asks us to consider if this is the point at which the line should be drawn morally and ethically.
In further defense of his position he talks about how humans are conditioned to have little disregard for the other animals with whom we share the planet. Man at one point, hunted and fished to sustain his own and his family's lives. Somewhere we have gone beyond that. We hunt and fish now not just for survival, but for sport, sacrificing the lives of animals just for our own amusement and pleasure not out of necessity.