Knowledge and truth

Leap of faith
December 25, 2019
The ethics of truth – religion
February 12, 2020

In 1963, Edmund Gettier invented some cases of being justified to believe something that is in fact false. Gettier addressed the relation between justification and truth to prove that justified true belief is a questionable definition of knowledge. Since then, opinions about the precise nature of knowledge continue to differ.

Knowledge of truth and truth of knowledge

Reality is the whole of what ever existed and will ever exist; if reality would be only what is real now, then it would constantly change over time. Part of reality will always remain unknown as long as we have a future, to not speak of lost knowledge that will never be recovered. And even if we believe to fully know something, new discoveries may lead to new insights: knowledge is not of, but about reality. It is always incomplete, which is exactly the reason why we keep craving for more.

If epistemologists want to define knowledge, they need to take a position about the nature of truth, but many of them are not very clear about that. Truth theories root deeply in metaphysics. Roughly, there are five theories. The identity theory says that truth and reality are identical wholes.  Along this line, many thinkers hold that understanding of particular truths – if they exist at all –  depends on understanding the whole and vice versa, leading to the position that truth cannot be known, but only understood. Neither can it be explained, but only displayed. The correspondence theory says that a belief – formulated in a proposition – is true only if it corresponds to a fact. Truth is sought on the level of particular truths. The coherence theory says that a belief is true only if it supports a coherent system of beliefs. Here we see a return to truth as a whole, but at the cost of dropping the relation between particular truths and reality. The pragmatic theory, in the classic phrase of Charles Sanders Peirce, says that “truth is the end of inquiry.” The end is a level of knowledge satisfactory to the agent, who is then confident that her truth is guaranteed not to conflict with subsequent experience. The four theories mentioned this far hold that ‘truth’ is somehow important, they inflate truth, like a balloon. The one theory opposing these is the deflationary theory of truth. that denies any metaphysical status of truth, see also The Metaphysics of truth.

Charles Sanders Peirce (1839 – 1914) as pictured by

I hold that truth is not identical to reality: ‘Truth’ expresses the truth value of our representations of reality. These representations are not necessarily correspondent or coherent propositions or sentences.  Our focus on propositions or sentences is a consequence of a need to store and share knowledge. But knowledge can also dwell in the mind in various other ways, for example as mental pictures, scents, sounds, etc.

Truth itself cannot be known, because it doesn’t exist as a being. If we should insist on calling truth an entity, it could only be the set of all particular truths, that is, of all true relations between reality and our representations of it. In that case, we would need a norm to classify every single one of these relations as an element of the Set of All Truths. The problem is that there is only one possible norm: truths will have to be true to make it into the Set of All Truths; here we enter on a path of regression.  

But let’s take a look from the bright side as well: within the Set of All Truths there would be no room for contradiction; truth would have to be a consistent whole because all members of the Set of All Truths satisfy the same condition for membership: being a true representation of some reality. If ‘the whole of knowledge’ would be essentially true, it would be a subset of the Set of All Truths, that is: the part of the quest for truth we completed. This knowledge would necessarily be a consistent whole also. Consistency is a metacondition also for truth, and thus for reality itself. But we cannot know if reality is consistent, we can only believe it is, implying that if we make truth an essential quality of knowledge, knowledge continues to rely on belief.

Wilfrid Sellars (1912 – 1989)

Part of the problem is what Wilfrid Sellars calls ‘the myth of the given’, the view that the ‘building of knowledge’ rests on rock-solid foundations of truth. However, to serve as a foundation, the ‘given’ must have inferential relations with the rest of knowledge, which is contradictory, since in that case it will no longer be ‘given’. If somebody sees a tomato for the first time, how could she call it ‘red’ if she had no – acquired – concept of red?

Still another argument comes from the historical development of knowledge. No doubt adherents of historical scientific paradigms believed that what they held was true knowledge, see Thomas Kuhn’s The Structure of Scientific Revolutions. Suppose we take ‘true’ as a condition for our present knowledge, and this knowledge becomes obsolete in the future, in that case, we would have been incorrect in defining what we know today as ‘knowledge’. It is modern arrogance to believe that knowledge is ever definite, but the more serious problem is that we need a definition of knowledge that holds across time. After all, many philosophers have eternalist views: reality is everything that ever existed or will exist; therefore, we need an eternalist definition of knowledge also.

Equally discomforting for believers in absolute truth is our failure to know when we have reached it. Even if we do possess true knowledge, we may still be unsure about its truth value. In short, the search for truth is a journey that can never reach its goal, unless that goal is the common effort of humanity for consensus. While truth is one of the qualities of knowledge, it is not an essential quality: knowledge is not always true. There would be no problem there if truth were seen as a secondary quality of knowledge. For a fruit to be an apple, it doesn’t have to be sweet, but its sweetness does make it more valuable to us.

Belief and knowledge

How to distinguish knowledge from – mere – belief? The essential quality of knowledge is that it necessarily requires access to facts, while belief doesn’t. If we flip a coin, there are two possibilities to know its final position: one is direct observation, to take a look, the other prediction, to combine other facts that we have access to – initial position, number of flips. To count as knowledge, direct observation requires fact-supported assertion, unless we go for radical interpretation: interpretation of observations directly from a set of beliefs.  This may include the belief that we are competent observers. Such a set of beliefs is known as an agent’s doxastic state.

Jennifer Nagel, professor of philosophy at the University of Toronto

Jennifer Nagel holds that knowledge is not a kind of qualified belief, but essentially different from belief. Knowledge, she says, is a mental state resulting from the desire of the agent to know, to be “latched on to the truth.” This position is essentially pragmatic, where distinguishing knowledge from belief depends on the agent’s confidence that she has reached her “end of inquiry”.  But first, confidence is a belief and thus knowledge will continue to depend on belief; second, how is the agent supposed to check that she is “latched on to the truth”? Nagel alternately uses “latched on to the truth” and “latched on to facts“.

But ‘truth’ and ‘fact’ should not be conflated, see also Knowledge and facts. Facts are not given aspects of reality, but representations of reality. Truth is a formal quality of facts. Other qualities of facts are practical usefulness, reliability across time, intelligibility, explanatory power, predicational power, etc. Simply put: knowledge is based on representations – whether or nor propositionally formulated -, truths are the formal truth values of representations. Yet we may well ask ourselves – as mankind – why truth is so important to us after the above-mentioned qualities of knowledge have been reached – most likely a serious case of truthopathy.

Justification and belief

Noam Chomsky (1928)

All humans have competences to create beliefs, either inborn or acquired. If we claim to know that before the boss and his wife left, there were five people in the room, we assume to be competent to distinguish a room’s inside from its outside, to conceptualize ‘people’ to not count in an accidental chimpanzee sitting there, to be able to count at least to three and to logically deduce that adding up the boss and his wife to that will make five people. Convincing evidence by Noam Chomsky and others shows that these fundamental competences are universal among humans; they are our basis to establish truths and they help to distinguish knowledge from belief by logically connecting representations.

Accounts by Donald Davidson and others claim that all beliefs are formed using the above mentioned elementary observational and logical competences. and therefore are radically true. Consequently, beliefs cannot qualify as knowledge if arguably formed against competent judgment. But radical interpretation doesn’t support belief; it rather relies on belief. Combining the ideas of Davidson and Nagel: if we classify radical belief as a kind of knowledge, then this kind of knowledge depends on the agent’s confidence that she is a competent observer. As said in the previous section, this confidence is part of our set of beliefs, that may be explicit or tacit, strong or weak, but all are part of our doxastic state and therefore influence our cognitive processes.

Reasons to believe something we call justification. This is not ‘to justify’ –  as an activity – but ‘being justified’ – as a state of affairs. Should belief be possible without any kind of justification, then it would be meaningless for the truth content of the belief: the belief being true would be a matter of luck. However, all our belief is justified from other beliefs – doxastically justified – be it from background knowledge, from experience, from an educated guess, from mindset, from faith, from superstition or from a gut feeling. All of these may be reasons for a belief only subconsciously as well. We are unable to perfectly exclude half-forgotten knowledge or vague prior beliefs from our thinking. We can neither ensure that a belief is strictly rational, nor that it is strictly irrational; the agent’s doxastic state can be ruled neither in nor out. Therefore, doxastic belief is an unreliable form of justification.

Justification and truth

Some mention ‘appropriate’ as a desirable quality of justification. What does appropriate justification mean? If we have some gut feeling about how a flipped coin will land, it would be appropriate doxastic justification in the sense that it is about the expected position of the coin. Let’s assume that we believe to have seen the coin to land heads up. To some, this already is sufficient reason to call their belief justified, even though gut feeling adds nothing in the sense of explanation. But apart from sense perception, also memory, prior knowledge, and subconscious logic are far from trustworthy. A belief to be justified requires a conscious linkage of the belief to facts. Accidently true belief isn’t knowledge.

I distinguish between two kinds of knowledge: knowledge-of and knowledge-about. Knowledge-of, sometimes also called acquaintance or radical knowledge is to know that something exists. Knowledge-about, or propositional knowledge, is connecting knowledge-of to other knowledge by way of propositions or sentences. Distinguishing between these two calls for precision. When a teacher points at her board and says “This board is white”, she might not be demonstrating knowledge-of, but knowledge-about. Knowledge-of would be: “This is a white (square, smooth) object.” Calling the object ‘board’ however would be knowledge-of only if she refers to the shape or the material of the object. In that case “This board is white” is a true proposition corresponding with the fact that there is a board that satisfies the quality of being white. Once she refers to its function as writing-board, she inherently tells why it is there, linking it to the whole of reality: board writing, classroom, school, teacher, students, career, economy, world.

We use elements of knowledge-of in more complex propositions to construct knowledge-about. bringing together knowledge of facts to support our belief. This we call propositional justification. It comes in two types, ex ante and ex post, since propositional justification may either precede or follow direct observation.

First picture of a black hole Wednesday, April 10, 2019, by Event Horizon Telescope

An example of justification ex post is a situation where nobody ever even dreamed of black holes until an unidentified black spot is surprisingly seen on a picture of the universe. The absence of propositional justification would not withhold people from knowing of a black spot somewhere in a picture of the universe. Then experts rush in to give explanations about its origin, nature, position, etc. Justification is ex post in all cases where agents radically know a phenomenon to have truly happened; therefore, justification ex post is no necessary condition for knowledge-of. Obviously, justification ex post depends on the – radically true – observation of that black spot: otherwise, there would be nothing to explain. On the other hand, knowledge-of is not linked to the whole of knowledge, not tested for coherence, it is seminal knowledge.

Belief in black holes was theoretically justified ex ante before taking a picture of one in 2019. Before the picture, did our notion of black holes count as knowledge? If we wouldn’t have called it knowledge, astronomers would have been forced to say: “We believe that black holes exist.” In fact, many of them cautiously did so. However, their belief in black holes was methodically justified and black holes existed, perfectly adding up to justified true belief. Moreover, if we deny cases lacking direct observational evidence to count as ‘knowledge’, we would render hypothetical quite a lot of physics, for instance, the existence of electrons. Therefore, in all cases where knowledge-about precedes or even predicts direct observation, truth-value depends on justification ex ante, rendering truth redundant.

Propositional justification is itself knowledge

Opinions may differ about what it is we see, and about why it is there. If we surprisingly see an unidentified black spot on a picture of the universe, the existence of that black spot is knowledge, because we see something, while at the same time we have no idea what it is we see. Keep in mind that doxastic justification will be there right away, ranging from believing to see a cloud of burnt matter to God’s eye watching us. But facts-related doxastic justification out of the blue contributes nothing in the sense of truth; we all saw the picture; we have a radically true belief of a black spot on a photo of the universe.

If we want to keep afloat our above-mentioned notion that all belief is at least doxastically justified, in the case of knowledge, propositional justification always overrules doxastic justification as soon as it becomes available. It is new knowledge about why the black spot is there. It is justification ex post because it tries to explain what we all saw, but it may at the same time be justification ex ante, if the explanation predicts how the black spot will develop, future observations of more black spots, etc.

All propositions we use are knowledge and thus in need of their own propositional justification, and so forth. These chains of justification lead back to radically interpreted basic facts. We simply cannot know if these basic truths were true in the classical, normative sense of corresponding with reality, but there is little reason to doubt them, after all, mankind survives. But there can be little doubt that our survival also depends on our competence to link seminal knowledge to the rest of what we know. This is in fact the main argument to state that knowledge of these elementary, radically interpreted facts is satisfactory since it successfully supports human existence. Since many of us, as Nagel writes, “crave for truth”, the idea of truth contributes to human existence, but it is only is one of knowledge’s secondary qualities, next to functionality, reliability across time, shareability, etc. The essential qualities of knowledge are that it is fact-based and propositionally justified.

Knowledge according to Calvin and Hobbes

We shall never know everything, but fear of skepticism is lack of confidence in the cognitive capacities of humanity. We better avoid burdening knowledge with the criterion of being an absolutely true representation of reality; as Willard Van Orman Quine wrote, the term ‘knowledge’ does not mark a clear subject of inquiry, knowledge is a whole. Knowledge is the whole of mankind’s propositionally justified beliefs.

“Our scientific theory can go wrong, and precisely in the familiar way: through failure of predicted observation. But what if… we have achieved a theory that is conformable to every possible observation, past and future? In what sense could the world then be said to deviate from what the theory claims? Clearly in none. “ Willard Van Orman Quine: Theories and Things, 1981.


  1. […] The question if God exists is a bad question, because first, it can be answered neither logically nor from experience and second, it has undesirable moral consequences, see The ethics of truth. And there is still a third reason: the fundamental difference between belief and knowledge – see Knowledge and truth. […]

  2. […] essential quality of knowledge is not that it is true – see Knowledge and Truth –, but rather that it requires access to facts we can interpret using our cognitive competences. […]

  3. […] of reality? We already saw Wilfrid Sellars speaking of the “myth of the given”, see Knowledge and Truth. Most foundationalists however adhere to the correspondence theory of truth, claiming that facts in […]

  4. […] Knowledge and Truth, I wrote that knowledge is supposed to refer to facts. But what are […]

  5. […] the nature and boundaries of knowledge – knowledge was often defined as justified true belief. In Knowledge and truth, I demonstrate why this theory is wrong. In The metaphysics of truth, I already wrote that truth is […]

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