General point of epistemology

"Epistemology" is the study of knowledge. Many philosophers take it to be the investigation into the conditions for knowledge. Some think those conditions are largely psychological in nature.

When we speak of "knowledge" in Epistemology, we mean knowledge-that knowledge. We mean "propositional knowledge." Propositional knowledge covers a wide range of propositions, some mundane (like "You are wearing a hat right now") to scientific (like "The universe consists of X subatomic particles") to extramundane (like "God is the supreme creator of the Universe").

In analyzing such propositions, we map them to the definition of knowledge (provided below).

"Epistem-ology"

"Episteme" translates to, from the Greek, "knowledge." "-ology" means "study" or "reason" or "science" (it is derivative on "logos").

It's important to note that "knowledge-how" is related to the Greek "techne." These two classes of knowledge firmly exclude one another. I might know how to ride a bike without knowing any proposition about bikes nor might I even know what to tell you to help you ride one. This kind of knowledge is unrelated to the definition so given.

Knowledge is different from belief

Look, when someone says "I know that you are happy right now" they are saying something, raising the epistemic bar, so to speak, quite different from "I believe that you are happy right now".

If the former, you might be skeptical and ask for justification or you might say "No, no, the truth of the matter is thus."

If the latter, you very likely will not ask for justification. You might just brush it off with some cliche like "To each his own" or "So many heads, so many opinions."

In a word, knowledge is stronger than belief. It is essential that you understand their relation. Knowledge, knowledge-that in this case, presupposes belief. It is essential that you understand what "presupposition" means.

Knowledge presupposes justification, belief, and truth. In this way, in this sentence, we mean more-than-just plausible justification or evidence, genuine belief, true statements. Knowledge would not presuppose insincere beliefs, unconvincing evidence or falsehoods. Just think about it; that's silly.

What we mean when we say that we know

This issue here is NOT--I REPEAT NOT--just about predicating knowledge to someone. It is not just about saying "Oh he knows", though predication is very important and factors in. This is not just about watching TV and applying the definition to the people on the screen. It is the definition of knowledge, not just the grounds for ascription. Imagine someone you've never met before and will never meet. You have no character profile of this person. This person is faceless and has no identity but more or less can apply reason and thought. Think about the bare minimum this person can know, given the right resources and evidence and charitability.

Knowledge defined

S knows that p if and only if[INDENT] S believes that p (belief condition) if and only if[INDENT] S thinks that p is true

S acquires the belief that p in a causally appropriate way (normative principle of belief formation)
[/INDENT]S has evidence to believe that p (justification condition) if and only if[INDENT] Ceteris paribus, Any at least human rational being Sn would accept the evidence given

(Non-)evidentiary justification, E, is criticism-free
[/INDENT]p is true (truth condition) if and only if[INDENT] p is worthy of being asserted (normative operational principle and weak verificationist constraint on assertibility) if and only if[INDENT] p is consistent with reality (correspondence theory)

p coheres with a field of relevant beliefs (coherence theory)

p is pragmatically-constrained (pragmatic theory)
[/INDENT][/INDENT][/INDENT]Note: Consider the no-theory theory of truth in the definition of truth.

Other relevant definitions

"Objective" =def mind-independent

"True for" =def believes for oneself (non-knowledge context; idiomatic use of "is true"); more akin to "is genuine" or "prefers" ("That's true for me"-Translation: "I prefer it thus and so").

"Subjective truth" =def As is clear by "true for," this term is idiomatic; in some cases it is fruitful to point out that it is a contradiction in terms, if the person means to argue about "truth" in the knowledge-that or knowledge context sense)

"Subjective" =def mind-dependent (Whether or not the cat is on the mat is true does not depend purely on the status of my mind or your mind. Thus, there is a class of entities which can be true regardless of the status of one's or anyone's mind. (Refutation to "Global Relativized Truth"; not that anyone really assents to this bogus notion.)

"Inter-subjective" =def consensus (not convention or norm or nonvolitional agreement) That we all wear jeans is not an inter-subjective truth (this is a convention or a social norm); that we all more or less accept that the sky is blue makes this proposition an inter-subjective truth (though some of us may not be able to supply a scientifically convincing explanation at any given time).

"Statement" =def Stronger than grammatical declarative; or, as the joke goes, grammarians would be omniscient. ("The square root of my dog is pleased" or "The numbers are angry" or "God is a turnip every Wednesday at 8′o clock"-examples of nonsense, they are pseudo-statements, but nevertheless declarative-grammatical.) Record of a fact that stands the test of the logico-grammatical form.

"Proposition" =def That which is expressed by the statement. "Il pleut aujourd'hui" and "It is raining today" are both statements which express the proposition that it is raining. "p" in the literature is usually substitutable with logico-grammatical statements, and "p" is called a propositional variable.