Theory – Definition, Types, Concept, Elements, and Examples


We explain what a theory is, its elements, and its types. Also, scientific theories, systems theories, the Big Bang theory, and more.

What is a theory?

Surely we often hear that someone has a theory, that they came up with a theory or that they are not convinced by certain theories. This is a common and colloquial use of the term, which does not always imply its fair and true meaning, but is often confused with another.

The word theory comes from the Greek word theaomai, “contemplate” or “look,” linked to theoros, “spectator,” and théatron, “place to see,” from which the term theater comes. Already in ancient times this word was used in a figurative sense, to refer to a speculative, intellectual gaze, as a synonym for “seeing beyond the obvious” and ended up being synonymous with lucidity and understanding.

Now, in a strict sense, theories are logical-deductive systems that serve as support for the scientific models through which we interpret and explain objective reality. Which means that a theory is a series of laws that account for a certain phenomenon in the universe, and that normally involve three elements:

  1. A set of proven hypotheses, which serve as a starting point.
  2. A field of application, that is, the things that the theory explains.
  3. A set of rules that allow valid consequences to be drawn from hypotheses.

As will be seen, when we talk about a theory, especially in the field of science, we are not talking about speculation, nor about one occurrence or possible explanation among many, but about a true logical framework of evidence, arguments and demonstrations that constitute a unified system. Contrary to what its popular usage suggests, a theory is the closest you can get scientifically to the truth.

In research, however, different results than those predicted by theory may be obtained (due to procedural flaws, among other reasons), which is why a distinction is often made between theory and practice. Thus, we speak of theoretical results to refer to those possible results, but that did not occur in reality. Obviously, we should not confuse them with the theory itself.

Types of Theory

Broadly speaking, we can distinguish three types of theories, which are:


that identify and detail the features of one or several events or phenomena under study. They seek to create an objective model that reflects the actions of nature.


that cover two or more different phenomena to find the correlation between them and determine the fundamental laws that contain their relationship. They are those that try to build cause and effect relationships.


that based on a cause and effect relationship already described and explained, they are dedicated to induction, that is, to the extrapolation and projection of possible phenomena or unsuspected links between phenomena. They seek to connect distant points in the matrix of reality.

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Scientific Theories

Scientific theories are those that are proposed as a set of principles or explanations to account for an observed phenomenon. To do so, they are based on the description of observable phenomena and the linking of proven hypotheses, according to the principles of falsifiability and demonstrability proposed by the scientific method.

More simply put, these are the theories that scientists have built, based on immense volumes of information obtained from the observation of reality, the recording and verification of different hypotheses, and finally the construction of a reasoning model. that gives everything verifiable meaning. Therefore, a scientific theory should never be confused with a hypothesis.

Scientific theories, as we said before, are the most refined and reliable form of knowledge that humanity has been able to build, through a rigorous method of verifications, evaluations and experiments. But this does not mean that they are absolute or irrevocable explanations.

Given that science is a field of knowledge in perpetual updating, it is always possible that new, more complex theories will emerge that supplant the current ones, as humanity gains more and more knowledge about the universe, and has more and better instruments to support it.

Systems Theory

Known as Systems Theory or General Systems Theory, it is a field of study that proposes a scientific approach to systems in general, in order to deduce laws and principles that serve to describe reality, always understood, of course, as a set of systems.

A system is a portion of reality, endowed with concrete limits, that has interrelated and interdependent parts whose sum is always greater than the sum of its parts. That is, the modification of one element of the system affects the other parts, in such a way that it can be studied and predicted.

In this way, a living being, a climatic mechanism or practically any section of reality that can be abstracted from the environment and evaluated according to the aforementioned can be thought of as a system. Seen this way, the general laws of systems apply equally to all of them.

Big Bang Theory

The Big Bang Theory is often called the cosmological model that is most valid and scientifically accepted today, that is, the best-supported set of scientific explanations that we have regarding the origin of the universe and its subsequent evolution.

Its name comes from English (Big bang, “big explosion”) and is due to the fact that, according to astronomical studies and the conclusions obtained from them, our universe was found 13.8 billion years ago completely concentrated in a single point.

At that time, a mysterious event known as a singularity took place, thus giving rise to all matter, space and time in the universe. Thus, a “big explosion” marked the beginning of time and the beginning of all things that exist.

The Big Bang Theory, in the strict sense, does not offer explanations about the way in which the universe began to exist, as much as evidence regarding its initial states of development and the long process of changes that took place from that remote moment until today: the continuous expansion of space, the formation of matter, etc.

Lamarck’s theory

Lamarckism or Lamarck’s Theory of Evolution is the formulation that the French naturalist Jean-Baptiste Lamarck (1744-1829) made of the Theory of Evolution at the beginning of the 19th century. Today this theory is considered obsolete, but at the time it constituted a revolutionary idea, since it contravened the creationism prevailing at its time with scientific thinking, even anticipating the British Charles Darwin by 50 years.

Lamarck’s vision assured that life was not created, nor was it immutable, but that it came from simpler forms, which over time had changed to adapt to their respective environments, thus giving rise to the biological diversity that we know today.

As evidence of this process, which according to Lamarck occurred gradually and imperceptibly, he cited the fossils known at the time, claiming that they were intermediate forms, halfway between the originals and the definitive ones, that is, between the primitive and those evolved or adapted to the environment.

Lamarckism can be considered a precursor to the theories of evolution accepted today, especially considering that at the time of its appearance few of today’s paleontological findings were known, and biology was unaware of many of the secrets about inheritance that Today they are common knowledge.

The theory of evolution

When we talk about the Theory of Evolution, as can be understood from the previous case, we are not really referring to just one, but to a set of postulations, studies, theories and scientific formulations around the origin of life and reason. of biological diversity. All of them, over time, converged into a single one, in force today, called the Modern Evolutionary Synthesis.

The central postulate of evolutionism is that living beings were not created by supernatural entities, but that all life always comes from a previous form of life.

Later, in a long chain of living beings dating back to primitive times, some traits were preserved and others eliminated. This occurred as different species of living beings, over time, competed with their peers and other species for access to food resources, living space, and the right to reproduce.

Quickly summarized, the Theory of Evolution explains the competition inherent in all forms of life, in which some feed on others, and understands it as a “natural selection” that favors the fittest species, that is, the best adapted. to the environment and the rules of biological competition, above the less suitable.

The first, thus, reproduce abundantly, and the second, on the other hand, become extinct, leaving with the passage of time only the suitable species, which will then be subjected to new pressures and a new selection, thus giving rise to new and new ones. species over the millennia. In this way, the most favorable genes are preserved from one species to another, while the least favorable ones are lost.

All life on Earth, therefore, is found on some branch of the immense family tree of species, at whose roots would be the last universal common ancestor (LUCA), a primordial species that, through of diversification and adaptation to its different competitive environments, gave rise to the different kingdoms of known life.

Hello, I am Sunny Yadav. I am a writer and content creator. Through my blog, I intend to create simple and easy to understand content that will teach you how to start your online journey!

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