Like a great many problematic and disputed concepts in society today, the idea of animal rights can be traced to the Enlightenment period in the seventeenth century.
During the Enlightenment, philosophers and political commentators put a tremendous emphasis on the idea of “natural rights” as an alternative to the traditional concept of natural law which had informed western civilization’s understanding of justice and virtue for almost two thousand years.
Within the framework of natural law, rights were essentially responsibilities one had to others according to the precepts of justice. That a man had a “right to work” was not primarily a description of something he was owed by others, but something he ought to do. And because working to support and feed his family was something a man ought do, it became incumbent on others not to interfere with his obligation.
With the advent of the Enlightenment, this notion of justice and right action got inverted: the right to work was no longer a precept of justice, but an entitlement. How such entitlements (like the “right to free speech”) was to be determined was not clear and, to this day, the origin and metaphysical foundation of “rights” (in the Enlightenment sense) remains highly contentious and debated.
One can see why this inversion was, in a sense, necessary and even inevitable: without the absolute foundation of God’s eternal law (which formed the basis of jurisprudence in western civilization) the human person and his exercise of reason became the sole arbiter of what was deemed rational or not. Without an external reference to an objective moral guide, the internal reasoning of the individual became the measure by which things were weighed up and evaluated.
It is the context of the natural law and natural rights dichotomy that we should examine the question of “animal rights.” It becomes immediately evident that there can be no coherent concept of “animal rights” in a system of thought rooted in the natural law: animals are of course incapable of taking on “responsibilities” and therefore do not have “rights”. This is not to say that animals shouldn’t be treated responsibly; rather, the benign and humane treatment of animals was not something an animal was entitled to, but rather something we were obligated to do because the human person, made in the image and likeness of God, was tasked in the Book of Genesis with the stewardship of the earth.
Once the metaphysical foundation of the natural law had been dismantled in the Enlightenment, the seventeenth century philosopher was confronted with the challenge of explaining why the human person was obligated to treat animals humanely. Consequently, the “natural rights” theory was extended to animals, because--in the Enlightenment context--it was the task of human reason to bestow reason upon everything within its grasp.
Everyone knows (and always had known) that treating animals with cruelty was wrong and somehow violated human conscience. But the philosophical basis upon which such cruelty is decried is going to be either, in broad strokes, derived from the traditional notion of the person as being made in the image and likeness of God, or from the Enlightenment notion of the animal made in the image and likeness of man.