Propositions and Claims, Belief and Knowledge

The fundamental building block of knowledge is a declarative statement, also known as a claim or a proposition. A declarative statement is one of 4 types of statements that also include exclamations, questions, and commands. Declarative statements are distinguished from the others in that they have truth value; they can be characterized as either true or false, or probably true or probably false.

The statement "Apples are on sale at the supermarket for .5€ a dozen" is declarative. It makes a claim about a state of affairs existing at the local market. It may be true or false. 

In contrast, the exclamatory statement "Holy cow, what a deal," the command "Go buy me a dozen," or the question "What's an apple?" cannot be called true or false. Our goal is to determine which of these declarative statements justifies our belief.

What does it mean to say, "I believe X."? 

If I believe the claim that apples are on sale for .5€ a dozen, it means that I expect to be able to buy apples for five cents a dozen if I go to the store. However, the command to buy some apples or the exclamation that I am happy about the opportunity, set up no such expectation.

What does all this all means for us? For any statement to even be considered as a candidate for belief, it must "assert some state of affairs that can be expected". Such statements are said to have cognitive content they convey something that can be known. "If the statement contains nothing to know then there is nothing there to be believe." 

Although all declarative statements presumably have cognitive content, not all actually do. This is not a problem if the lack of cognitive content is obvious, for example, the declaration "The square root of Wednesday is an odd number." This statement is stink of nonsense. 

There are other declarative statements, whose lack of cognitive content is not so obvious. This can be a problem, because such statements can fool us into thinking that a claim has been made that sets up an expectation, when in fact, no claim has really been put forward. These pseudo-declarative-statements are essentially meaningless claims or empty propositions.

Although meaningless claims are not valid candidates for belief, this does not stop many people from believing in them. The vague predictions made in the daily astrology column or the nebulous promises made by promoters of bogus health cures are examples of meaningless claims. Those who believe these empty propositions simply do not realize that what they have been told has no cognitive content. 

A way to tell if a statement has cognitive content and is a valid candidate for belief is the discernible-difference test described by Hall: "Statements with cognitive content make claims that are either true or false; and whether they are true or false makes a difference that can be discerned. That is why these statements offer something to believe and why there is no point in trying to believe a statement that makes no such offer".

In other words, a proposition that passes the discernible-difference test sets up an expectation such that the state of affairs, if the statement were true, is recognizably different from the state of affairs, if the statement were false.

The discernible-difference criterion can be applied to statements purporting to be predictions. A prediction is a claim to know something about the future. If a prediction has cognitive content, it will be clearly discernible in the outcome if the prediction was accurate or not.

The truth or falsity of the claim apples are on sale for .5€ a dozen will make a discernible difference when I get to the market. It is this discernible difference that allows the claim to be tested. Testing a claim on the basis of a discernible difference is central to the scientific method. 

Hall, in his book Practically Profound, explains why he finds Freudian psychoanalysis to be meaningless when examined in light of the discernible-difference test. 

"Certain Freudian claims about human sexual development are compatible with all possible states of affairs. There is no way to confirm or disconfirm either 'penis envy' or 'castration complex' because there is no distinguishable difference between evidence affirming and evidence denying these interpretations of behavior. Exactly opposite behaviors are equally predictable, depending on whether the alleged psychosexual stress is overt or repressed." 

The requirement of "cognitive content rules out all statements that are so loose, poorly formed or obsessively held (e.g., conspiracy theories) that there is no recognizable difference between what would be the case if they were so, and what would be the case if they were not." In a like vein, the Intelligent Design Theory carries no cognitive freight in the sense that no matter what life form is observed it is consistent with the notion that it manifests an underlying form specified by some intelligent designer. 

What then is knowledge? 

Knowledge can be defined as justijied true belief. Hence, in order for a declarative statement to qualify as knowledge, not only must it be a candidate for belief, because it has cognitive content, but it must meet two other conditions as well. First, it must be true (or probably true). Second, the statement must be believed with justification. A belief is justified when it is based on sound inferences from solid evidence. 

Prehistoric humans held the false belief that the sun moved across the sky because the sun orbited the earth. Clearly they were not in possession of knowledge, but suppose that there was a prehistoric person who believed correctly that the sun moved across the sky because of the earth's rotation. Although this belief was true, this individual could not be described as possessing knowledge. Even though they believed what astronomers ultimately proved to be true, there was no evidence yet to justify that belief. Without justification, a true belief does not attain the status of knowledge. 

These concepts are illustrated in the figure at the begining of this article.

From this it follows that erroneous beliefs or false knowledge fail to meet one or more of the necessary conditions of knowledge. Thus, an erroneous belief can arise either because it concerns a meaningless claim or because it concerns a claim that, though meaningful, is not justified by valid inferences from solid evidence.

Still, even when we have done everything right, by drawing the best possible inference from sound evidence, we can still wind up adopting erroneous beliefs. 

In other words, we can be justified in believing a falsehood, and honestly claim to know something, if it appears to be true according to logically sound inferences from the preponderance of available evidence. 

"We are entitled to say 'I know' when the target of that claim is supported beyond reasonable doubt in the network of well-tested evidence. But that is not enough to guarantee that we do know." 

Falsehoods are an unavoidable fact of life when we attempt to know things about the world based on observed evidence. Thus, knowledge based on the scientific method is inherently uncertain, and provisional, though less uncertain than knowledge acquired by less formal methods. 

However, over time, scientific knowledge improves, as it comes to describe reality in a progressively more accurate manner. 

It is a continual work in progress...