Auguste Comte, a French philosopher, presented the theory of The Law of Three Stages. He put forward this theory in his famous work ‘The Course in Positive Philosophy’ which was published in six volumes from 1830 to 1842.

This theory describes the evolution in the following two areas over the course of history.

1. Human intellectual development in three stages
2. Social evolution in these three stages

Comte believed that the human intellect (or style of thinking) has evolved in three stages in history. The main assumption of this theory is that human thought has advanced over the course of history such that human thought in each new stage has become more rational than the preceding stage.

These three stages of evolution of human thought are as follows:

1. Theological Stage
2. Metaphysical Stage
3. Positive or Scientific Stage

This is the first stage of human thought which is believed to have continued from the inception of human society to roughly 1300 AD. It is the earliest stage where people thought that all the natural phenomena are the product of divine or supernatural powers. People believed that everything in the universe is governed by divine forces. It was assumed that every happening is solely caused by divine forces. For example, when people faced a famine, they believed it is caused only by divine powers due to their bad actins which triggered the wrath of divine power. 

In this stage, the human intellect was restricted only to divine considerations. They generally lacked the ability to look into the rational considerations as causative factors for various things and happenings. For instance, they never thought that sowing seeds at the wrong time (season) of the year can also be a cause of the famine faced by them. Similarly, they never thought about many other causes for low agricultural productivity which are scientifically proven nowadays. Their thought revolved only around supernatural and divine power as a force of causation for anything.

The people had a strong belief in the divine power which they worshiped with utter respect. The theological stage was divided into the following three sub-stages depending upon the conception of divine powers in each stage.

1. Fetishism: In this stage, the people believed that divine powers are present in inanimate objects such as stones, trees, fire, volcano, sun, moon etc. People respected and worshiped these objects. This stage is also known as animism.
2. Polytheism: In this stage, people believed that there are many gods who provide different services, e.g., the god who provides food, the god who showers rain, the god who gives children to a married couple and so on. People worshiped different gods to get different benefits from them.
3. Monotheism: In this stage, people believed that there is only one God which is the creator and operator of everything in the universe. They started to worship only one God.

It is the second stage which is believed to have continued from 1300 AD to 1800 AD. In this stage, the intellectual level of human beings became more advanced as compared to the previous stage. The people started to think that different phenomena (that happen in relation to them or in their surrounding) are not only determined by the divine powers but also by certain rational factors. They believed that the events in the world are caused partially by divine powers and partially by rational factors. They realized that they have certain strengths and capabilities; and thus, they also have some control on happenings around them. In other words, they started to think that their actions can also influence different phenomena in relation to them or others. They started to take rational considerations into account for explaining a phenomenon. For instance, the famine at a certain point in history was assumed to have not caused only by the divine powers but also by some rational factors such as not using proper tools of farming, using bad quality or less quantity of seeds, not using natural fertilizers, climatic changes as a result of human activity, farming on infertile land, not sowing seeds or not watering them in proper timings of the year and so on. Therefore, they partially considered those rational factors and partially divine factors as causative factors for different phenomena.

It is the third stage that is believed to have started in 1800 AD and gained its full maturity in the onward period. In this stage, the intellectual level of people became highly advanced. The people adopted a purely scientific approach to look at the world. They started to believe that every event in the world operates purely on rational principles. Therefore, in this last stage, they discard those assumptions which cannot be proven scientifically; and thus, only accept those facts which can be proven scientifically.  

They seek scientific explanations for every phenomenon with the help of systematic procedures of inquiry such as experimentation, measurement, statistical evidence, observation, testing and verification. People tend to believe only in scientifically provable ideas and facts. Therefore, they value objectivity, accuracy, precision, and verifiability as pillars of true exploration. This stage continues and the scientific approach of human beings to look at the world is getting further refined over time.

Comte believed that human intellect is an agent of social change because the way people look at the world has an impact on the structure of their society. Therefore, the evolution in human thought over time also manifested its effect in the societal structure in these three stages in history. In other words, the evolution in human intellect in each stage also caused an evolution in their social organization in each stage.

Therefore, the law of three stages can also be understood as a theory of evolution of social organization in three stages. The characteristics of social organization in these three stages are as follows.

1. The family was viewed as the most important social unit by the people.
2. Priests were viewed as the leaders by the people, and they were the most influential people in society.
3. Comte termed this society as a military or monarchial society where God was viewed as the most powerful and at the top of the hierarchy of kings.
4. It refers to the ancient society where one’s family or kinship group was the most important social group for the people. People due to their hard faith in divine power viewed God as behind everything that happened to them. Therefore, they gave a lot of respect and value to priests and accepted them as their leaders. There was relatively less peace and order in societies in this stage because people would engage in combats against one another. They made groups of individuals and prepare them for the combats with other people. Society was ruled by these groups, or by an individual viewed as the King. In the hierarchy of rulers, God was at the top.

1. The state was seen as an important social entity by the people. People started to also think beyond their immediate groups such as family and thus, also gave importance to the collective wellbeing of the people in general. They started to view themselves and others as members of the state (as a common social group) and such that every member of the state deserves equal importance.
2. Churchmen and lawyers were viewed as leaders by the people. People started to realize the role of makers and definers of law for the stability and proper functioning of society. Therefore, the churchmen and lawyers received equal importance in society.
3. Comte termed this society as a legal society because the lawyers and policymakers had good control in society.
4. It refers to the society at the beginning of Enlighten era. The people were tired of the tyrannies of the monarchs and wanted to get freedom from them. They were motivated for this goal by the sensible people of the community which acted as lawyers to define to them the policies for harmony and prosperity of the society. In this way, laws and policies were valued by the people which became a basis for the operations of the state and thus, people started their journey towards democracy.

1. The entire human race is viewed as important by the people. Human thought broadened beyond their state and started to have good feelings for the entire human race irrespective of state, religion, language, race and other such factors. They started to see themselves and others as members of the entire mankind (as a common social group) and such that every member of mankind deserves equal importance.
2. Scientists are viewed as the leaders by the people. As scientists provide verified information in relation to different things and spheres of life which contribute to the betterment of people, they became the most influential people in society.
3. Comte termed this society as an industrialized society. The industry has a great hold in such a society because they provide for the needs of people as well as contribute to the economic growth of the society.
4. It refers to the modern society which is characterized by scientific and technological advancements. Scientific advancements contribute to the comfort and ease of life. Scientists are valued in this society because through their scientific inquiries, they contribute to the social as well as economic development of the society.