The reason these are false is that Classical Greek had more than one word for knowledge: there are essentially four words for different types of knowledge, and there are additional words having to do with the source or origin of the knowledge. As the title suggests, we will be considering three of them.
Doxia: Opinion or Statement, with the connotation of mere opinion. It is part of the word “orthodox”, with “ortho” meaning: straight. correct, or right. As in orthopedic ('leg straightener'), or orthodontist ('teeth straightener'). A less frequently used sense of doxia as 'praise' is preserved the the “Great Doxology.”
In English: Doxia corresponds to statements of either fact or opinion. For example: “green is a color” or “green is the best color.” Doxia is a type of knowledge that may or may not be the real case, that is, it may not correspond to what we can test by reason or measurement, or may include what cannot be tested.
Cognitively: this type of knowledge can be thought of as one type of memory. If someone asks you a question and you remember the answer, then that one example of doxia as knowledge. A piece of doxastic knowledge can be isolated, or unrelated to other knowledge. It can also co-exist with a contradictory piece of knowledge.
In Learning: Learning doxia is often referred to derogatorily as “regurgitation” in the sense that one memorizes (ingests) then demonstrates memorization (regurgitates). However, essentially all education begins by learning doxia, as the other types of knowledge occur within the individual.
In Argumentation: Staying at level of opinion or statements of “truth.” Or, considering everything to be a matter of opinion. Such as, “My opinion is as good as anyone else's.”
Episteme: Systematic or interrelated knowledge, or Understanding. Also, professional or practical skill. Episteme is a compound word in Greek, literally meaning: “to stand or erect upon.” It is constructed upon previous knowledge and can in turn be constructed upon itself, hence the systematic or interrelated nature. Classical philosophers referred to the understanding they gained from reasoning about it as episteme. For example, the Socratic Method is one that examines doxia through reasoning in dialog. Part of the word “epistemology”, with “logos” meaning speech, account, or reason.
In English: episteme corresponds to most of what is meant by the word “knowledge”. It is also the term that described professional skill, such as the practice of: science, law, and philosophy. It is the type of knowledge or understanding that would qualify someone as an expert witness in a court of law, for example. This knowledge may not already exist within the knower as doxia, but can be derived from the system of existing knowledge. Someone who is knowledgeable in the sense of episteme, can not only present a conclusion (which would be doxia), but can derive or explain the conclusion as well, that is, take someone through a process to gain episteme of their own.
Cognitively: episteme is much more complex and uses more than one type of memory. It involves agentic cognition (from “agent”), that is, the active use of and direction of thought. This thought utilizes skills in reasoning, already established system of related knowledge, and a general understanding of the situation or framework for meaning (a paradigm).
In Learning: This is the level where a student not only remembers the facts, but has developed an understanding. The knowledge has been internalized and can be considered in part, as a whole, and in relationship. It remains theoretical or abstract knowledge in many ways. The limitations of episteme can be seen in such contrasts as “knowing versus know-how,” and in “education versus experience.”
In Argumentation: Justifying statements and deriving conclusions using valid reasoning demonstrates some level of episteme. However, there is a difference between systematic knowledge and simply related knowledge. Merely giving a reason for a statement that is only another statement, whereas episteme is demonstrated in a way that someone could follow in constructing their own episteme. Often following such demonstrations requires a great deal of prior knowledge, skill, or even experience.
In the Republic, Plato uses the distinction between a doxastic cognition and an epistemic cognition as the justification for the statement that “philosophers should be rulers, or rulers philosophers.” The philosopher is better suited to rule because he uses epistemic cognition as the basis for judgment.
Gnosis: what enables recognition, an ingrained familiarity, experientially derived (as opposed to sensed), structural or irreducible “being” knowledge. The word gnosis is used to describe knowing someone, or knowing a landscape. It is a part of “diagnosis,” the process of recognizing an illness.
In English: there is no corresponding term. We can see echoes of it in notions like “hands-on experience,” but they fall short. Usually we are reduced to analogies, like the “difference between knowing the path and walking the path.” Or, “the map is not the territory.” Some aspects of an eye-witness refer to gnosis, such as recognizing a perpetrator. Yet, the circumstances may limit the process of gnosis, and this has been demonstrated to be susceptible to recognition of the suspect rather than the perpetrator. A better example in the use of gnosis is the practice of having a body identified by the next of kin.
Cognitively: Gnosis is outside of the range of agentic cognition. It is developed through an experiential process in the individual, but not directly through consciously directed thought. While derived from and related to experience, it is not simply sensory in nature. It isn't a memory of the senses, for example. This can be seen in the process of recognition. We are able to recognize people after dramatic changes, or written text that is fuzzy, scrambled, or misspelled.
In the general sense particular types of gnosis are related to particular regions of the brain. This can be seen in cases such as facial agnosia, where a brain lesion leaves someone unable to recognize faces. They still have the sensory data from looking at someone's face, but there is no recognition. It takes an epistemic process of deduction to determine who someone is. In general, gnosis is a type of meta-knowledge that is fundamental to who we are in the world.
In Argumentation: Difficulties in using gnosis in argumentation go back at least as far as Plato. Early dialogs that use dialectical reasoning to examine a matter of opinion or statements of definition (doxia), end without a firm resolution of whether what was examined was mere opinion or merely inadequately expressed. In later works Plato introduced the notion of Forms as a way to include aspects of gnosis.
When it appears in English, particularly when it is capitalized, Gnosis refers to a particular type of gnosis: the redemptive or liberating gnosis that was sought by the ancient Gnostics, and mentioned frequently in their scriptures. In these scriptures Gnosis is related to a particular mythological/symbolic framework. This reflects some kind of participatory view, an understanding that this framework was a vital (if not necessary) tool for attaining liberating gnosis. However, this framework does not exhibit the hallmarks of episteme, it isn't consistent, and has many variations—it just isn't systematic. What these stories reflect is efforts to express Gnosis in a way that might lead someone to their own gnosis to some limited extent.
We've all read gripping stories that made us feel like we were “there.” The Gnostic scriptures, as we have them, don't have the narrative qualities that might engage us as a modern reader. The New Testament, for example, is very terse. There are no rich descriptions of events, for example, just the bare bones. They are more in the line of “seeds” of a full narrative that a contemporary storyteller might give. We see this particularly in the Gospel of Thomas, where the longest story is only a few sentences. Yet, they are still stories, and the type of gnosis that they were seeking to lead one towards isn't gnosis of the scenes or of how the characters looked.
Gnosis is also developmental. One seeks it. One attains it. Yet, one already has it in some way, but it isn't manifest. In the Hymn of the Pearl there is the recognition of the truth of the letter (or call to awaken), because the letter was written in his heart.
Gnosis is also transformational. Descriptions of the transformation of the individual through attaining Gnosis in ancient texts include: rebirth, resurrection, redemption, liberation, and awakening.
Gnosis was not the goal of Gnostics, but rather the means. Gnosis was the path. As GRS Meade wrote:
They are now generally referred to in Church history as the Gnostics, those whose goal was the Gnosis,—if indeed that be the right meaning; for one of their earliest existing documents expressly declares that Gnosis is not the end—it is the beginning of the path, the end is God--and hence the Gnostics would be those who used the Gnosis as the means to set their feet upon the Way to God.