§1 The Nature of Truth

In critical thinking, we often argue about whether a claim is “true,” but we rarely stop to define what “truth” actually is. To be a Reasonable Person, you must understand that “truth” is not a singular, simple concept. It is a property of propositions that we verify using different logical and philosophical “tests” depending on the context.

1.1 The Importance of Definitions

Logic is the study of the relationship between statements, but if the terms within those statements are “fuzzy” or poorly defined, the logic fails.

• Lexical Definitions: These tell us how a word is commonly used (dictionary definitions).

• Precise Definitions: These are used in philosophy and science to reduce vagueness.

• The “Boundary” Function: A definition tells us what a thing is and, more importantly, what it is not. Without clear definitions, we fall into the Fallacy of Equivocation (Chapter 4), where the meaning of a word shifts mid-argument.

1.2 Necessary vs. Contingent Truths

Philosophers categorize truths based on how they are true. This distinction, often traced back to Gottfried Wilhelm Leibniz, is vital for knowing what kind of evidence you need to provide.

• Necessary Truths (A Priori): These are true in all possible worlds. You do not need to look at the world to know they are true; you only need to understand the definitions of the terms.

  • Example: “A triangle has three sides” or “$A = A$.”

  • Logical Status: Denying a necessary truth results in a contradiction.

• Contingent Truths (A Posteriori): These happen to be true in our world, but they could have been otherwise. They depend on the way the world actually is.

  • Example: “It is snowing in Ellensburg right now.”

  • Logical Status: To verify a contingent truth, you must use your senses or empirical data.

1.3 Theories of Truth: How We Test for Facts

How do we decide if a proposition “earns” the label of Truth? Philosophers use four primary frameworks:

A. The Correspondence Theory

This is the most “common sense” view. A statement is true if it corresponds to a fact in the external, physical world.

• The Test: “The cat is on the mat” is true if and only if there is actually a cat on a mat.

• Strength: It aligns with the scientific method and empirical observation.

B. The Coherence Theory

This theory argues that a statement is true if it fits logically within a larger system of beliefs.

• The Test: If you are told that a human flew across the room by flapping their arms, you reject it as “false” not because you saw them fail, but because it contradicts your coherent system of physics and biology.

• Strength: It is essential for checking internal consistency in complex systems of thought, like mathematics or law.

C. The Pragmatic Theory

Developed by American philosophers like William James and Charles Sanders Peirce, this theory suggests that “Truth” is what works in practice.

• The Test: If believing in a specific medical treatment leads to a cure and allows you to function, that belief has “cash value” or “practical truth.”

• Strength: It focuses on the real-world impact of ideas rather than abstract metaphysics.

D. Relativism and Postmodernism

• Relativism: The claim that truth is “relative” to a person (Subjectivism) or a culture (Cultural Relativism).

• Postmodernism: A skeptical movement (associated with thinkers like Michel Foucault) that argues “Truth” is often a “social construct” used by those in power to control those without it.

• The Critical Caveat: While it is true that perspectives vary, a Reasonable Person recognizes that “Absolute Relativism” is self-defeating. (If you say “There is no absolute truth,” is that an absolute truth?)

§1 Summary Table: Which Truth-Test Are You Using?