History of Animal Rights

• The history of the idea of animal rights has been a slow process from protection of the welfare of animals to broader expansion.  The first known law protecting animals in was passed in Ireland in 1635, and prohibited pulling wool off sheep and attaching plows to horses' tails.
• The German philosopher Arthur Schopenhauer was the first major Western philosopher to advocate animal rights, when he wrote that Europeans "awakening more and more to a sense that beasts have rights, in proportion as the strange notion is being gradually overcome and outgrown, that the animal kingdom came into existence solely for the benefit and pleasure of man" in the mid 1800s.
• Interestingly, the first European country to pass comprehensive animal protection laws was Nazi Germany. 
• Probably the most important contemporary philosopher who advocates increasing rights of animals is Peter Singer, who wrote Animal Liberation in 1975.
• Tom Regan wrote The Case for Animal Rights in 1983.

Arguments for Animal Rights

• Singer bases much of his argument in favor of animal rights on utilitarianism, the principle that the best decision leads to the greatest happiness for the greatest number of people.
• He rejects the idea that humans or non-humans have natural or moral rights, and proposes instead the equal consideration of interests, arguing that there are no logical, moral, or biological grounds to suppose that a violation of the basic interests of a human—for example, the interest in not suffering—is different in any morally significant way from a violation of the basic interests of a non-human. 
• He also argues that animals are capable of feeling pain. According to Singer, scientific publications have made it clear over the last two decades that the majority of researchers do believe animals suffer and feel pain, though it continues to be argued that their suffering may be reduced by an inability to experience the same dread of anticipation as humans, or to remember the suffering as vividly. In the most recent edition of Animal Liberation, Singer cites research indicating that animal impulses, emotions, and feelings are located in the diencephalon, a region well developed in mammals and birds 
• Regan argues that the crucial attribute that all humans have in common, he argues, is not rationality, but the fact that each of us has a life that matters to us; in other words, what happens to us matters to us, regardless of whether it matters to anyone else. In Regan's terminology, we each experience being the "subject-of-a-life." If this is the true basis for ascribing inherent value to individuals, to be consistent we must ascribe inherent value, and hence moral rights, to all subjects-of-a-life, whether human or non-human. The basic right that all who possess inherent value have, he argues, is the right never to be treated merely as a means to the ends of others. 
• Singer argued that failure to extend rights to animals merely because they lack reason would open the door to mistreating humans with severe disabilities.

Arguments Against

• One of the most common arguments against animal rights/vegetarianism is known as the Ben Franklin Defense. Franklin argued that since animals do not show mercy to each other, humans should not feel any obligation to them. According to Singer, Franklin was for many years a vegetarian, until one day, while watching his friends fishing, he noticed that some of the fish they caught had eaten other fish.  He then said to himself: "If you eat one another, I don't see why we may not eat you."
• Others argue that animals must be capable of understanding rights. Carl Cohen, a professor of philosophy, wrote that "rights holders must be able to distinguish between their own interests and what is right.  "The holders of rights must have the capacity to comprehend rules of duty governing all, including themselves. 

Modern Context: Factory Farming

Daniel Degrazia argued in this 2002 book Animal Rights: A Very Short Introduction that factory farming does more harm to animals than any other human activity.  He wrote:

Considering both numbers of animals involved and the extent to which they are harmed, factory farming causes more harm to animals than does any other human institution or practice.  In the USA alone, this institution kills over 100 million mammals and five billion birds annually.  American farm animals have virtually no legal protections.  The most important applicable federal legislation is the Humane Slaughter Act, which does not cover poultry - most of the animals consumed - and has no bearing on living conditions, transport, or handling.  Moreover, as Gail Eisnitz and others have extensively documented, the Act is rarely enforced.  Apparently, the US Department of Agriculture supports the major goal of agribusiness: absolute maximization of profit without hindrance.  This is not surprising when one considers that, since the 1980s, most top officials at USDA either have been agribusiness leaders themselves or have had close political and financial ties to the industry.