While euthanasia has been widely practice even in the ancient times, opposition against mercy killing still continues until today. Saint Thomas Aquinas is one of the most vocal figures during the earliest times who believed in the sanctity of life. In fact, the saint argued that euthanasia violates the natural laws of life--survival. The ethical and moral beliefs of those countries and states in the US that openly practice euthanasia at present is founded on the basic tenet that suffering among living things whether humans or animals should not be tolerated.
However, before discussing whether euthanasia is morally good or bad, it should be noted that the constructs of mercy killing must be clearly defined. That is to say that while the principle of euthanasia applies to both humans and lower forms of animals like cats and dogs, the weight of the ethical issue is lopsided to the human aspect. The evidence: more laws and provisions have been drafted on human mercy killing as compared to that of the lower forms of animals. The only law perhaps in the US that gives attention to domesticated animals and perhaps endangered animals is the Animal Cruelty Act.
As Rene Descartes had argued, the only thing that separates humans from the rest of the animal kingdom is soul. Hence, the notion gives humans the license to kill lower forms of animals that are of less importance. But how do we know which is important or not? It is also interesting to note that the principle on the equality of life blurs that difference between humans and other animals. That is; if the equality of life should be followed, then no living organism has the right to take the life of other living organisms. Simply put, vegetarians cannot eat plants and animals if that should be the case. But the law of nature does not permit such. In a very harsh environment, it is a matter of eat-or-be-eaten construct--the very basic principle of survival and coexistence.
Animals slaughtered for food and tested in the laboratory so that humanity's chances of survival would improve are some of the aspects of the benefits of animal euthanasia. Further, euthanasia of domesticated r-selected species such as rats and cats are also used for population control.
However, in the human context there may be unrealized benefits and downsides. The potential benefits: on the side of the patient's family, hospital costs can be saved and rather expended to funeral cost and other household expenditures. Although some say that life is priceless, some doctors who recommend the family to remove the life support of the patient gives a realistic overview of the futile battle with death. On the patient's end, the benefit if such a term could be used, is to immediately end his or her pain and suffering from an incurable disease.
In the animal context, euthanasia can become very problematic when an attachment is formed between a pet and its owner. However, animal euthanasia is inevitable in certain respects because higher order of animals like human also requires a high protein diet to carry out their metabolic functions. The case is also similar to large mammal predators of the feline family. But the disadvantage of animal euthanasia has not yet been completely realized.
Perhaps the downside of euthanasia in the human context is the possibility that this act of mercy killing could be abused by authorized people. Pro-life individuals contend that everybody deserves the dignity to die. That euthanasia is a matter of deciding one's life in behalf of someone else's life violates the principles of having the right to die on your own.
It is this difference in the moral and ethical beliefs of humanity that have sustained the debate on euthanasia over time. Whether mercy killing should be sought or avoided is a matter of a case to case basis to some people. If one contends with an absolutist who believes that euthanasia is morally and ethically wrong, it is expected that he or she will never be open to the idea that euthanasia is a case to case basis and that there are situations that one could find mercy killing more humane and reasonable. He or she will surely fight to the end that euthanasia is wrong and, therefore, should not be sought.
But all of these justifications of mercy killing depend on the values that a man puts to the life of other people or organisms involved. Again, certain instances present itself to humanity that can make it difficult to avoid difficult choices such as euthanasia. For instance, slaughtering beef, pork, chicken and other types of meat to provide humans their daily nourishment of protein may certainly be difficult to avoid especially when the word survival comes into play. However, if a situation provides more options such as pet adoption and castration of animals to prevent death and further reproduction respectively, then it may be possible to lower the statics of euthanasia. Although if the approach on the perception of euthanasia is cultural, then there goes the saying "you can never argue with culture because you will never win."
Whether euthanasia is right or wrong, desirable or not than any other alternatives, still, again, depends on the constructs of the practice and how an individual values his or her ethical and moral beliefs of right and wrong. But over the years there has been the emergence of the taxonomy of euthanasia. This emerging taxonomy allows people to discuss which type of euthanasia is permitted and which crosses the boundary of killing someone in good faith and committing homicide. The categorization placed on euthanasia suggests there are instances in which euthanasia is "morally less objectionable." Garrard and Wilkinson contended that there are no reasons to not consider the legalities of passive euthanasia. In passive euthanasia, the life support of an individual is immediately cut because a negative quality of life that awaits such that the life of a patient is expected to be worse than his or her death. The main reason to cause death is for the best interest of the patient. In this case, withholding treatments means that the human body does not have the dexterity to continue because the treatment is too much to handle. Thus, the act of mercy killing is not just to intentionally kill because on perceive's that it is hopeless for the other to survive with their incurable disease. Garrard and Wilkinson have laid certain provisions that should be met in order to justify the means. Apprehensions towards passive euthanasia are reasonable because it is sometimes difficult to assess a patient's condition. However, if the reasons and constructs are well-defined, medical personnel should be less worried about the legalities of passive euthanasia.
Garrard, E. and S. Wilkinson. "Passive Euthanasia." Journal of Medical Ethics, 31(2005): 64-68. Print.