Friedrich Nietzsche is a German philosopher who is best known for his ideas on the 'will to power' and the 'superman'.

Social constructivism is a theory in sociology and philosophy that states that knowledge is socially constructed, rather than being objective or absolute.

Empiricism is a theory in philosophy that states that knowledge is gained through experience, rather than through reason or intuition.

Rationalism is a theory in philosophy that states that knowledge is gained through reason, rather than through experience or intuition.

Idealism is a theory in philosophy that states that knowledge is gained through intuition, rather than through reason or experience.

Pragmatism is a theory in philosophy that states that knowledge is gained through action, rather than through reason, experience, or intuition.

Fallibilism is a theory in philosophy that states that knowledge is always provisional and subject to change, rather than being certain or absolute.

Foundationalism is a theory in philosophy that states that knowledge is based on a foundation of self-evident truths, rather than being provisional or subject to change.

Coherentism is a theory in philosophy that states that knowledge is based on a network of interconnected beliefs, rather than on a foundation of self-evident truths or on experience.

Skepticism is a theory in philosophy that states that knowledge is impossible, or that at least there is no way to be certain of anything.

Progressivism is a theory in philosophy that states that progress is inevitable, and that society is always moving forward.

Conservatism is a theory in philosophy that states that progress is not inevitable, and that society can regress, and that therefore it is important to preserve traditional values and institutions.

Liberalism is a theory in philosophy that states that progress is possible, but that it is not inevitable, and that therefore it is important to protect individual rights and freedoms.

Socialism is a theory in philosophy that states that progress is possible, but that it is only possible through revolution, and that therefore it is important to overthrow the capitalist system.

Liberalism is a theory in philosophy that states that progress is possible, but that it is only possible through gradual reform, and that therefore it is important to protect individual rights and freedoms.