Propositional knowledge is one of the most fundamental and widely discussed forms of knowledge in epistemology, the philosophical study of knowledge. It refers to knowledge of facts or truths, expressed in the form of propositions. A proposition is a statement that can be either true or false, and propositional knowledge involves knowing that a particular proposition is true. Understanding the nature of propositional knowledge is crucial for comprehending the structure of knowledge itself, as it is often considered the most basic type of knowledge.
In this essay, we will explore the nature of propositional knowledge, its key components, the challenges to its definition, and the various philosophical views surrounding it. We will begin by defining propositional knowledge and distinguishing it from other types of knowledge. We will also examine the traditional and modern theories of propositional knowledge, including the famous “justified true belief” (JTB) theory, and discuss the problems and critiques raised against it. Finally, we will look at some of the contemporary responses to these issues and the ongoing philosophical debates surrounding the nature of propositional knowledge.
1. Defining Propositional Knowledge
Propositional knowledge, often referred to as “knowledge-that,” is knowledge of specific propositions or statements. A proposition is an assertion that can be either true or false. For example, the proposition “The Earth orbits the Sun” is a statement that expresses a fact, which can be true or false. When we say that we know that the Earth orbits the Sun, we are referring to propositional knowledge.
To understand propositional knowledge more clearly, it is helpful to compare it with other types of knowledge. There are primarily three kinds of knowledge:
- Propositional Knowledge (Knowledge-that): Knowledge of facts or truths, such as “The sky is blue” or “2 + 2 = 4.”
- Procedural Knowledge (Knowledge-how): Knowledge of how to do something, such as knowing how to ride a bicycle or solve a math problem.
- Acquaintance Knowledge: Knowledge of something through direct experience or familiarity, such as knowing a person or a place.
Propositional knowledge is often considered the most straightforward and foundational type of knowledge. It is about knowing that something is the case. For example, “I know that Paris is the capital of France” expresses propositional knowledge. This form of knowledge is typically conveyed through statements or propositions and is central to many fields of human inquiry, including science, history, and everyday life.
2. The Traditional Account of Propositional Knowledge: Justified True Belief
The most widely accepted traditional definition of propositional knowledge is the justified true belief (JTB) theory. According to this view, for a person to know a proposition “P,” three conditions must be met:
- Belief: The person must believe that the proposition is true.
- Truth: The proposition must actually be true.
- Justification: The person must have sufficient justification or evidence to believe the proposition is true.
This view of propositional knowledge has roots in ancient philosophy, particularly in the work of Plato. In his dialogue Theaetetus, Plato examines the nature of knowledge and suggests that knowledge is belief that is both true and justified. The JTB account of knowledge was widely accepted for much of the history of philosophy, particularly in the early modern period.
To illustrate the JTB theory, consider the following example:
- Proposition: “It is raining outside.”
- Belief: You believe that it is raining outside.
- Truth: It is, in fact, raining outside.
- Justification: You have looked out the window and seen the rain.
If all three of these conditions are met, then according to the JTB theory, you know that it is raining outside. The belief is true, and you have a reasonable justification for believing it.
3. The Gettier Problem: Challenging the JTB Theory
Despite its widespread acceptance, the JTB account of propositional knowledge was challenged by Edmund Gettier in his famous 1963 paper Is Justified True Belief Knowledge? Gettier presented counterexamples where individuals satisfy the JTB conditions but still lack knowledge. These counterexamples, now known as Gettier cases, demonstrate that justified true belief is not sufficient for knowledge.
One of Gettier’s most well-known examples is the following:
Imagine a man, Smith, who has strong evidence for the belief that “Jones will get the job” because Smith has been told by the employer that Jones is the most likely candidate. Based on this evidence, Smith forms the belief that “Jones will get the job and Jones has ten coins in his pocket,” because he has seen Jones with ten coins earlier. However, in a twist of fate, Smith himself gets the job and also happens to have ten coins in his pocket. As a result, the proposition “Jones will get the job and Jones has ten coins in his pocket” is true, but Smith’s belief was based on a false premise, and the truth of the proposition was coincidental.
In this case, Smith’s belief was justified (he had evidence to support it), true (the proposition turned out to be correct), but not knowledge, because the truth of the belief was due to an accident or luck rather than a genuine connection to the evidence. This example led to a significant problem for the JTB theory, as it showed that justified true belief does not always equate to knowledge.
4. Responses to the Gettier Problem
The Gettier problem sparked widespread debate among epistemologists, and many attempted to revise or replace the JTB theory of propositional knowledge to address the challenges posed by Gettier’s examples.
a. No False Lemmas (NFL) Condition
One prominent response to the Gettier problem is to add the No False Lemmas (NFL) condition to the JTB account. The NFL condition asserts that for a belief to count as knowledge, the justification for the belief must not rely on any false assumptions or premises. In the Gettier example, Smith’s belief was based on the false assumption that Jones would get the job, which undermines the justification for his belief. By adding the NFL condition, the belief that “Jones will get the job and Jones has ten coins in his pocket” would not count as knowledge, because it relies on a false premise.
The NFL condition addresses some Gettier cases, but it has been criticized for being too restrictive or insufficient in addressing all possible scenarios of epistemic luck.
b. Causal Theories of Knowledge
Another response to the Gettier problem is to propose a causal theory of knowledge, which posits that for a belief to count as knowledge, there must be a causal connection between the belief and the fact that makes it true. According to this theory, knowledge requires that the belief is not only true and justified but also causally connected to the fact in the right way.
For instance, in the Gettier case where Smith mistakenly believes that Jones will get the job based on a false assumption, the causal theory would argue that the belief was not appropriately linked to the fact (that Smith himself got the job) in a way that guarantees knowledge. The causal theory focuses on the need for an appropriate causal relationship between belief and truth to avoid the epistemic luck found in Gettier cases.
c. Reliabilism
Another approach to resolving the Gettier problem is reliabilism, which suggests that a belief counts as knowledge if it is formed by a reliable process—one that tends to produce true beliefs over time. According to this view, if Smith’s belief that Jones would get the job was formed through a reliable process (such as a well-established hiring process), then it could still count as knowledge, even if it was accidentally true in the specific case.
Reliabilism emphasizes the reliability of the belief-forming process as a condition for knowledge, rather than focusing solely on justification or truth. This theory provides a potential solution to Gettier cases by shifting the focus away from the individual justification for a belief and onto the reliability of the cognitive processes involved.
d. Virtue Epistemology
Virtue epistemology is another approach that has been proposed in response to the Gettier problem. According to this theory, knowledge is not just about the relationship between belief, truth, and justification, but also about the intellectual virtues of the person who holds the belief. These virtues include traits like open-mindedness, intellectual courage, and intellectual honesty. For a belief to count as knowledge, it must be the result of the exercise of intellectual virtues, and the person must be actively engaged in forming and maintaining true beliefs.
Virtue epistemologists argue that the presence of epistemic virtues in the believer’s cognitive processes can provide a safeguard against the kinds of epistemic luck that lead to Gettier cases. A belief formed by an intellectually virtuous person is less likely to be the result of luck, making it more likely to qualify as genuine knowledge.
5. Conclusion: The Ongoing Debate on Propositional Knowledge
The nature of propositional knowledge remains a central issue in contemporary epistemology, with the Gettier problem continuing to stimulate philosophical debate. While the traditional JTB theory of knowledge was long the standard view, it has been shown to be inadequate in capturing the complexities of what it means to truly know something. The Gettier problem highlighted the role of luck in knowledge acquisition, leading to various responses, such as the No False Lemmas condition, causal theories, reliabilism, and virtue epistemology.
Despite the challenges posed by Gettier cases, propositional knowledge continues to be a cornerstone of epistemological inquiry. Philosophers continue to refine and develop new theories of knowledge in order to better understand the relationship between belief, truth, and justification, and to overcome the limitations highlighted by Gettier’s counterexamples.
Ultimately, the search for a more comprehensive theory of knowledge is an ongoing process, and it is likely that future philosophical work will continue to build on these debates, leading to a richer and more nuanced understanding of propositional knowledge.