Dualisms
Over the centuries many philosophers have seen a fundamental dualism. Most have invented their own names for this dualism. Not all have meant the very same things, but the great similarities allow us to collect all these dualisms into a chronological table, where similarities and slight differences become more clear.
Of course many have claimed to be monists. "All is One," they said, as they generally reduced the physical world to the ideal, or vice versa, or argued that the ideal and physical worlds were somehow both something else. But their underlying dualism was inescapable.
Many philosophers saw the need for the two sides to work together.

Immanuel Kant wrote

Gedanken ohne Inhalt sind leer.
Anschaungen ohne Begriffe sind blind.

Charles Sanders Peirce rewrote it as

If Materialism without Idealism is blind,
Idealism without Materialism is void.

With a nod to Kant and Peirce, we can say

Concepts without Percepts are empty.
Percepts without Concepts are blind.

And although Freedom and Values are not a Dualism, they too require one another and we can observe

Freedom without Values is Absurd (Existentialism).
Values without Freedom are Worthless (Positivism).

In Information Philosophy, we divide the world into three fundamental parts, the physical, the ideal (ideas are the same kind of abstraction as pure information), and the biological/human, a middle world of both ideality and physicality.
The ONE The MANY
Monism Pluralism
IDEALISM MATERIALISM
Being Becoming
Necessity Contingency
Plato's Divided Line
Theories (noesis)   Hypotheses (dianoia) Techniques (pistis)   Stories (eikasia)
Eternal Ephemeral
ESSENCE EXISTENCE
Universals Accidentals
Aristotle's Four Causes
Final Cause   Formal Cause Efficient Cause   Material Cause
Realism Nominalism
Intelligible Sensible
Form Content
General Particular
Absolute Relative
RATIONALISM EMPIRICISM
MIND BODY
a priori a posteriori
Certainty Probability
Intellect Tabula Rasa
Innate Learned
Analytic Synthetic
Kant's Transcendental Critique
Noumena Phenomena
Concepts/Thoughts Percepts/Senses
Categorical Hypothetical
Dialectical IDEALISM Dialectical MATERIALISM
Superstructure Base
Romanticism Positivism
Transcendentalism Pragmatism
Phenomenology Existentialism
Linguistic Analysis
Ideal Language Ordinary Language
Autonomy Mimesis
Deduction Induction
Theory Experiment
Consistency Correspondence
For Teachers
For Scholars

Chapter 6.3 - Dogmas Chapter 6.5 - Experiments
Part Four - Knowledge Part Six - Solutions
Normal | Teacher | Scholar