Key Difference: Essentialism states that any specific entity comes with a set of rigid attributes that define who or what it is. The theory states that each object, organism or anything that is in this world has a specific set of instructions and an essential reality behind them. Relativism runs on the opposite lines. According to this concept, there are no absolute truths only relative values. The truth changes depending on the beliefs and social norms. Relativism states that everything is subjected to change depending on perception and consideration.

Essentialism and Relativism are two concepts in belief. These concepts determine how things came to be and what they are. Both of these concepts are different from each other and refer to two different ways of looking at things. Essentialism is the belief that every entity has an essence that has made it what it is today. Relativism states that there are no absolute truths; that each thing is different in perception and consideration. The terms are popularly used in science and ethics. These terms are used to classify what is right and wrong.

Essentialism states that any specific entity comes with a set of rigid attributes that define who or what it is. For example: A dog would come with a set of attributes that would determine how he acts, behaves, looks, etc. The theory can be found in works of Plato and Aristotle and was known as Platonic Idealism. The theory states that each object, organism or anything that is in this world has a specific set of instructions and an essential reality behind them. They have an essence that determines what they are and what makes them up. According to Platonic Idealism, the essence of a thing/being is permanent, unalterable, and eternal.

The term is popularly used when dealing with ethics and is known as Ethical Essentialism. According to this theory all things have already been divided into right and wrong, what is morally correct and morally incorrect. However, each society or culture chooses to believe and change what is right and wrong. For example: According to Ethical Essentialism, human sacrificing is morally wrong; yet during the old civilizations it was considered as morally acceptable to sacrifice a human. This concept states that human sacrificing is morally wrong, even if the civilization chooses to accept otherwise.

Relativism runs on the opposite lines. According to this concept, there are no absolute truths only relative values. The truth changes depending on the beliefs and social norms. Relativism states that everything is subjected to change depending on perception and consideration. There are two popular types of relativism: Anthropological versus philosophical relativism. In anthropological relativism, the research is subjective when studying different cultures and beliefs of different societies and is not biased depending on their own views. In philosophical relativism, the data is interpreted depending on who studies it and what their views are. There are various other kinds of relativism that exist and are used in different fields of study.

Similarly, the term is also used when deal with Ethics. According to Ethical Relativism, all decisions cannot be classified in black and white; it has a lot of grey area. This theory states that the morality of actions depend on the culture that is currently doing it. The morality changes depending on the beliefs of the culture. Using the same example above; if the older civilization believed that it was morally correct to sacrifice humans then it was morally correct. However, now-a-days if human sacrifice is considered morally wrong; then it is morally wrong. 

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