Understanding Theories of Truth

1. The Question of Truth

Before we dive into the theories, it's crucial to be clear about the question we are asking. We are not asking which specific statements are true (e.g., "Is the Goldbach Conjecture true?"). Instead, we are asking a philosophical question about the nature of truth itself: "What does it mean for any statement to be true?".

Philosophers have traditionally sorted theories of truth into two broad categories: those that see truth as a substantive, important property that statements have (often called "inflationary" theories), and those that see it as a much thinner, less mysterious concept ("deflationary" theories). We will begin with the two most prominent substantive theories.

2. The Correspondence Theory: Truth as a Match with Reality

The correspondence theory is perhaps the most intuitive and oldest theory of truth. Its central idea is that a statement or belief is true if it accurately reflects, or corresponds to, the way the world actually is.

To get a clear initial picture, please watch this short lecture segment.

As the video explains, the core of the theory can be stated as:

A proposition is true if and only if it corresponds to a fact.

This simple formulation, however, hides significant complexity.

• What are "facts"? The theory posits a category of entities in the world—facts—that serve as the truthmakers for propositions. For a simple proposition like "the cat is on the mat," the corresponding fact seems straightforward. But what about negative propositions ("the cat is not on the mat"), or general ones ("all cats are mammals"), or mathematical ones ("7 is a prime number")? The theory seems to require the existence of strange-sounding negative, general, or mathematical facts.
• What is "correspondence"? The relationship between a proposition and a fact is not one of simple identity. How does a linguistic or mental item (a proposition) "match" or "picture" a piece of the world (a fact)?

To give this theory more substance, especially in a way that connects to your background in logic, we can look at the "neo-classical" version of the theory.

This version of the theory holds that propositions are complex, structured entities, often having a structure that mirrors the sentences expressing them. For example, the proposition that Ramey sings is composed of the individual Ramey and the property of singing. It is true if and only if there exists a fact also composed of Ramey and the property of singing, arranged in the right way.

The correspondence relation, on this view, is a structural isomorphism between the proposition and the fact.

Connection to Realism: The correspondence theory is the natural ally of the semantic realist. It provides a perfect account of a verification-transcendent notion of truth. Whether a fact exists or not is a matter of mind-independent reality, not our ability to discover it.

3. The Coherence Theory: Truth as Internal Consistency

The coherence theory offers a radically different picture. It denies that truth is a relation between a proposition and the external world. Instead, it claims truth is a property internal to a system of beliefs or propositions.

Let's return to Huw Price's lecture for a clear explanation.

The slogan for this theory is:

A proposition is true if and only if it is part of a coherent system of propositions.

The key points are:

• What is "coherence"? Coherence is more than just logical consistency. A coherent system is one where the beliefs are mutually supportive and interconnected. For example, in a detective's web of beliefs about a crime, each belief (motive, opportunity, witness testimony) reinforces the others.
• Motivation: The primary motivation is often epistemological. As Price mentions, we can only ever check our beliefs against other beliefs. We never seem to have direct, unmediated access to the "facts" themselves. Coherence theory embraces this, making truth a matter of this internal checking process.
• The Main Objection: The most famous criticism is that a system of beliefs could be perfectly coherent and yet be entirely false—a well-constructed fantasy novel, for instance. The theory seems to cut truth off from the world entirely.

For a more detailed list of the standard philosophical objections, let's turn to the Internet Encyclopedia of Philosophy.

Connection to Anti-Realism: The coherence theory has a strong affinity with anti-realism. Both views are "internalist" in that they locate the conditions for truth within our systems of knowledge and belief, rather than in a mind-independent world. However, it's important not to equate them. Dummett's anti-realism, for example, focuses specifically on proof and justification rather than the more general notion of coherence.

4. Deflationary Theories: Truth as a Logical Device

The correspondence and coherence theories are "inflationary"—they treat truth as a deep, substantive property in need of philosophical analysis. Deflationary theories reject this entire picture. They argue that truth is not a substantive property at all.

This short video clip provides an excellent, non-technical introduction to this way of thinking.

The classic starting point for deflationism is the Redundancy Theory, often associated with Frank Ramsey. It is based on the simple observation that saying "P is true" seems to be just a more verbose way of saying "P".

For example:

"It is true that snow is white" has the same content as "Snow is white."

The predicate "is true" appears redundant; it adds no new content.

However, the truth predicate is not always redundant. This is where modern deflationary theories, such as disquotationalism, refine the idea. Consider a statement like:

"Everything the Pope says is true."

We cannot rephrase this as an infinite conjunction of everything the Pope might ever say. Here, the truth predicate is not redundant; it functions as a crucial logical device. It allows us to endorse or generalize over a potentially infinite list of propositions. For the disquotationalist, this is the primary function of the truth predicate. It's a tool for disquotation and generalization, not for naming a deep metaphysical property.

This view takes the Tarski biconditionals, such as:

...not as a starting point for defining a substantive property (as Tarski did), but as exhausting everything there is to say about the concept of truth. The concept is defined entirely by this logical role.

Connection to Realism/Anti-realism: Deflationism seeks to dissolve the traditional debate. If truth has no substantive nature, then the dispute over whether it's verification-transcendent (realism) or epistemically constrained (anti-realism) is a pseudo-problem. The entire debate, a deflationist would argue, rests on the mistaken "inflationary" assumption that truth is a property with a deep nature to be discovered.

Conclusion

Today we have surveyed the three major families of theories about the nature of truth. Each offers a profoundly different answer to Pontius Pilate's ancient question, "What is truth?".

Key Takeaways:

• Correspondence Theory: An inflationary theory holding that truth is a substantive relation between a proposition and a fact in the world. It is the natural partner for semantic realism.
• Coherence Theory: An inflationary theory holding that truth is a substantive property of a proposition's membership in a coherent system of beliefs. It has strong affinities with semantic anti-realism.
• Deflationary Theories: A family of theories that deny truth is a substantive property. Instead, "true" is seen as a logical device used for purposes like generalization. This view attempts to sidestep the traditional realism/anti-realism debate.

This lesson concludes the first module of our course. You are now equipped with a philosopher's toolkit containing some of the most fundamental distinctions and concepts in the field: metaphysics vs. epistemology, realism vs. anti-realism, and the major theories of truth.

Preview of the Next Lesson:

With these foundational tools in hand, we are now ready to begin our historical and philosophical investigation of logic itself. We will start by examining the thought of Immanuel Kant. His views on the nature of logic and judgment set the stage for the revolutionary developments that would follow, and his distinctions—particularly between analytic and synthetic judgments—became a central battleground for the philosophers who would create modern logic.