here is the list of the most famous ‘ism’ theories

• Absurdism.
• Agathism
• Agnosticism
• agnostic theism
• agnostic deist
• Anthropocentrism
• Chronocentrism
• Empiricism.
• Existentialism
• Essentialism
• Determinism
• dualism 
• monism
• Nihilism
• Optimism
• pessimism
• Pragmaticism
• Rationalism
• Realism‎ 
• Stoicism
• sentimentalism
• Universalism

Absurdism.

Absurdism is the philosophical theory, very similar to Existentialism and nihilism. they all share the belief that the universe is meaningless.
Proponents of absurdism like Albert Camus(Father of Absurdism) claim that humans are meaning-seekers, but they cannot find anything meaningful because there is no intrinsic meaning in the universe. and this conflict between the humans incessant desire and the meaningless world has made life absurd. Albert Camus gives as a final possible solution how humans may react to absurdism . . . instead of confronting the world in search of meaning, humans must understand the absurdity of the universe and rebel against the absurd Nature itself.
whereas nihilism argues that we must understand not only that there is no intrinsic meaning in the universe, but also that it makes no sense to try to construct our own meaning as a substitute or solution. Existentialism differs from nihilism and Absurdism because they belief individuals can create their own meaning in their lives.

Agathism

The doctrine that all things tend towards ultimate good, as distinguished from optimism, which holds that all things are now for the best.

Agnosticism

Agnosticism is the philosophical belief founded by the British biologist Thomas Henry Huxley, that the existence of God cannot be proven logically or scientifically (i.e. God is, inherently unknowable).
The followers of this philosophy neither believe in the existence of God nor argue that God does not exist. literally An agnostic philosopher is someone who neither believes nor disbelieves in the existence of a God.

agnostic theism

agnostic theism is the philosophical idea that even though the existence of God cannot be proven logically or scientifically, God exists or most likely god may exists .

agnostic deism

agnostic deism is a philosophy that believes in the existence of God . Agnostic deist believe that God created the universe everything correctly and accordingly and this God does not interfere the universe after creating it.

Anthropocentrism

anthropocentrism is a philosophical belief , that humans are the most powerful and superior of all creatures.

Chronocentrism

Chronocentrism is the idea that the present (right now is more important(impactful) than all of your past or the future.

Empiricism.

Empiricism is the philosophical theory that belief the source of human knowledge is observations and experience (i.e mainly gained through the use of the senses organs). Francis Bacon (the father of empiricism), john Locke, George Berkeley, and David Hume are some of the most famous empiricism philosophers

Existentialism

Existentialism is The philosophical belief, that life has no predetermined, predetermined purpose and meaning, and that we are the ones who can shape our destiny, personality, and values ​​the way we want. Essentially the essence of this philosophical idea is that although there is no intrinsic meaning in life, individuals have the freedom to create, shape and determine their own meaning in life.

some of the most existentialist philosophers are Søren Kierkegaard(considered as the father of existentialism), Jean-Paul Sartre(who is considered as the central figure of existentialism), Martin Heidegger, Karl Jaspers and Gabriel Marcel

Essentialism

Essentialism is the Contrary philosophical theory of existentialism, It is the philosophical belief that people and things have natural essence (innate meaning), with immutable constant collective properties derived from nature that make things the way they are. broadly speaking individuals existence to Essentialism is defined by thier natural essence whereas to Existentialism individuals existence is determined by indivisuals the way the give essence(meaning) to existence.

Determinism

a theory or doctrine that acts of the will, occurrences in nature, or social or psychological phenomena are causally determined by preceding events or natural laws.

dualism 

Dualism is a philosophical belief, founded by the French philosopher Rene Decartes , that human beings are composed of two separate entities mainly the mind and the body.

monism

Monism believes that all things in existence are part of the same unified oneness. Some monists call this God, believing that there is one God and that God is in all things. However, other monists call this unified oneness something else other than God, such as the Universe, the source, nature, or other names.

Nihilism.

Nihilism is a form of extreme pessimism , that believes , – life has no inherent meaning or value. fo a nihilist there is no reason to uphold moral principles for himself or anyone else. because Everything, including truth, is meaningless. it is also meaningless to try to construct one’s own meaning as a substitute or solution.

Optimism

optimism, the theory, in philosophy, that the world is the best of all possible worlds or, in ethics, that life is worth living. It is derived from the Latin optimum (“best”).

pessimism

Pessimistic describes the state of mind of someone who always expects the worst. A pessimistic attitude isn’t very hopeful, shows little optimism, and can be a downer for everyone else. To be pessimistic means you believe evil outweighs the good and that bad things are more likely to happen.

Pragmaticism

dealing with things sensibly and realistically in a way that is based on practical rather than theoretical considerations.

Rationalism

Rationalism is a philosophical theory that belief the reliable source of knowledge is only reason and logic. René Descartes  is considerea as the fother of modern rationalism.

Realism‎ 

realism, in the arts, the accurate, detailed, unembellished depiction of nature or of contemporary life. Realism rejects imaginative idealization in favour of a close observation of outward appearances. As such, realism in its broad sense has comprised many artistic currents in different civilizations

Reconstructivism is a philosophical theory holding that societies should continually reform themselves in order to establish better governments or social networks.

Stoicism

Stoicism teaches the development of self-control as a means of overcoming destructive emotions; the philosophy holds that becoming a clear and unbiased thinker allows one to understand the universal reason

Self-discipline is being strong or building calmness in the face of problems.

sentimentalism

Signs that someone is being sentimental with you may include nostalgic conversations, sharing meaningful memories, giving thoughtful gifts related to shared experiences, expressing deep emotions, and showing genuine concern for your well-being

Universalism

Universalism implies that it is possible to apply generalized norms, values, or concepts to all people and cultures, regardless of the contexts in which they are located