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Hello and welcome to my educational/informative blog post about the philosophical topic "Opinion and knowledge". This is an extended version of a short version I've linked in a main blog post on this topic. I did that because, while I was doing my research on this topic, I collected quite a lot of information from the other sites and I asked my subscribers and friends if they were okay with exposing the proofs that supported my short version (final version of my research), and so here you go. Please enjoy reading this, and please leave a comment on the main post!

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Since this extended version is quite long, I'd recommend using these links to quickly navigate my blog post.

• Logical principles
  

Knowledge of abilities

In order to have knowledge, it is necessary to know the sources of knowledge (cognition) and their truth, how true can knowledge be?
Cognition is an understanding of reality based on human experience and opinion. It includes any mental process that can be described as the experience of knowing, perceiving, recognizing, reasoning, and inferring.

Epistemology can talk about the types of cognition of abilities. It is a field of philosophy that explores the possibilities, the roots of continuation and the ultimate reaches of human knowledge. Epistemology deals with the types of cognitive abilities based on one of its questions: What are the sources of knowledge? How was certain knowledge acquired?

Immanuel Kant was a philosopher who also dealt with epistemology. He believes that knowledge about an object can exist only if it is possible for that object to be given in experience. Kant's theory of knowledge is summed up in the statement: “Thoughts without content are empty; intuitions without concepts are blind.” This means that knowledge is a combination of thoughts and intuitions (content and concepts).

Therefore, according to Kant, cognitive abilities, that is, sources of knowledge, are:

• Sensory experience - indirect
• Reason - indirectly
• Intuition - directly

There are two types of knowledge:

• Knowledge a posteriori - knowledge gained through experience
• Knowledge a priori - knowledge that exists in the subject independently of any experience

Reliability of knowledge

A learned position is true if it corresponds to reality, if it is obvious, if it fits into previously established truths, and if it can be verified. The question is, however, how many attitudes there are that meet all these conditions. Truth is a complex category and therefore is still an open philosophical question.

Criteria for acceptance of findings

In order for some knowledge to be objective, it must meet certain criteria; so knowing about something:

• must be clearly formulated in language.
• it must be possible to identify the discovery under certain conditions
• must be able to explain the discovery (answer questions)
• under what conditions the discovery can be repeated, ie. to find out

Knowledge: justified true belief

One of the most influential modern definitions of knowledge states that knowledge is justified true belief. Let's take a closer look at these important terms:

1. Knowledge must be justified. It is not enough to "knock" or "guess" the truth to say we have knowledge. You see that sense in answering questions at school: mere luck is not proof of your knowledge. You need to explain why something is the way you claim, that is, to give a justification for your claim. Only with justification (or: proof) do we fulfill one of the necessary (necessary) conditions to claim that we know something.

2. Knowledge must be knowledge of truth. Even the ancient Greek philosopher Socrates claimed that it is logically impossible to have knowledge of a falsehood: saying "I know that the Earth is a flat plate" is simply not knowledge, because it is not true that the Earth is a flat plate. Knowledge can be the only knowledge of what is true, and for this reason logic is closely related to the scientific methods of determining truth.

3. Knowledge must be associated with belief in what we claim to know. Here we can introduce an essential difference between the concepts of truth and sincerity, that is, lying and falsehood. The one who lies does not necessarily have to tell the truth: it is enough that he does not believe that what he is saying is true. In other words, a liar can tell the truth. For example, John is late for class and says: "I'm sorry, I'm late because I had to miss a bus-65, there was a terrible crowd!" - John, in fact, was late because he went out with his friends last night and slept over at a friend's house, he was coming in the bus-45, but the teacher was in the aforementioned bus-65 and really saw that it was unbearably crowded. So John is lying, but he told the truth! In short: honesty is saying what we believe to be true, lying is saying what we think is untrue, while truth and falsity themselves have no direct relation to what we say. For knowledge, therefore, we need to believe that what we say is also true.

Theories of truth

Theories of truth deal with the question: What is truth? They explain the true definition of truth and give examples of what is really true.

Theories of truth are:

• Correspondence theory
• Theory of verification (empiricism and pragmatism)
• Coherence theory
• Theory of evidence

Correspondence theory says that what corresponds to reality is true (Adequatia intellectus ad rem - Thought coincides with reality). Although this is our everyday understanding of truth, correspondence theory has a problem: there are statements based on sense perceptions that are wrong. For example, for more than a thousand years it was believed that the planet Earth was the center of the cosmos - mere sensory perception said that the entire firmament revolved around our planet. Therefore, the words "the firmament revolves around the Earth" correspond to our sensory perception.

Verification theory is based on the truth of a position that can be verified. We have a division into empirical theory (empiricism) and pragmatism, two philosophical sciences that rely on the theory of verification. Empiricism is based on a truth criterion that requires sensory experience. For example, "prolonged use of narcotics is addictive" - ​​empirically verified.

Pragmatism looks for the practical beneficial consequences of a position in order to consider it true. For example, if, because of the belief that the Earth is round, we still go on a journey around the world (like the navigator Magellan) and return to the city from which we started, our belief was actually true - because it had a practical consequence, i.e. use.

However, like the correspondence theory, the verification theory also has a problem: the practical success of a position (or theory) is not necessarily proof of its truth, because in certain circumstances even wrong positions can lead to a useful outcome.

Coherence theory solves the problem of subjectivity by saying that what is true is what is consistent with previously accepted views (previous "truths"). If an attitude does not contradict what we already consider to be true, that is, if its consequences are also acceptable within the belief system we have, then that attitude will be true.

Problem: It is possible to construct coherent systems of attitudes and beliefs that are actually wrong, i.e. untrue, because we still do not have enough knowledge, and therefore coherence itself is not a sufficient condition of truth. Examples: the belief that the Earth is the center of the cosmos. A paranoid person has a coherent belief system: the expectations and fears they feel are indeed consistent with the system of "truths" the person has built.

The theory of evidence is based on the obviousness (evidence) of truth. For example, two is greater than one. Although there seems to be no problem here, there is when the obvious truth is checked. The problem is that the obviousness is tied to the perceiver or the thinker: if it is a different person or culture, something else may be obvious, and our view may also be patently untrue. For example, in geometry (Euclidean) it is quite evident (obvious) that two parallel lines never intersect, while in the geometry of curved space this is not true. Also, what is an obvious difference between red and green to most - is not to a colorblind person.

Therefore, it can be said that theories of truth function on the basis of cognition of abilities.

There are some other types of attaining truths:

• Dogma is a scientific position, thesis, claim or principle of a particular philosopher or philosophical school, which are considered irrefutable, cannot be refuted or are considered essential, i.e. characteristic of a certain philosophical or scientific system. A generally accepted and clearly formulated opinion or teaching that does not allow it to be doubted or leave the possibility of being refuted or discussed.
• Intuitive insight, or intuition, is the direct attainment of truth without the help of reflections and logical conclusions; direct observation.

Opinion as a subject of the study of logic

Logic in a broad sense: It is defined as a philosophical discipline that examines the forms of rational thought, its rules and methods.

Logic in the narrower sense: It is defined as the science of reasoning, because it is a form of rational thinking to which only it gives rules.

As a science, logic is formal, non-empirical and normative, making it akin to mathematics and other formal sciences.

Logical principles

Classical logic has its roots in Aristotle's logic and its main features are based on several principles of thinking:

• Principle of bivalence - it states that every statement has exactly 1 of 2 truth values ​​- it is either true or false.
• "You are tall" is either true or false. So either "it is the case that you are tall" or "it is not the case that you are tall" must be true.
• The principle of identity - states that one thing is equal to itself, if something is A, then it is A and cannot be something else.
• All roses are considered roses.
• The principle of (non)contradiction - it is formulated in several ways:
• Nothing can be A and not-A at the same time.
• If an animal is a cat, the same animal cannot be a non-cat. Or, logically speaking, if it is +p, then it is not -p, +p cannot be -p at the same time and in the same sense.
• Of the 2 contradictory statements, 1 must be false.
• It depends on the type of statement. If it is the simple statement "All cows eat grass" and the counter-statement "No, not all cows eat grass", then one or the other is true.
  
  However, "contradictory" cannot mean not "A=B" or "A is not equal to B", but two statements that differ. for example:
  
  “2=3.” “No, 2=4” They contradict each other in the sense that they claim two different things about A. But both are wrong, in fact 2=2.
  
  But there are statements that are more complicated, and each can be partially true, or occasionally true, or true at different times, such as "the US is a country" and "the US is not a country" - both of which are false at some point. Or "I love you" and "I don't love you". Both can be true or false, even at the same time. Or "the particle passed through the left slit" and "the particle did not pass through the left slit" (meaning it somehow passed through both slits).
• The principle of exclusion of the third – is expressed by the statement: out of 2 contradictory statements, 1 must be true.
• For any statement, either that statement or its negation is true. For example, "it's raining here now" and "it's not raining here now." Therefore, one of these two statements must be true.

Form and content of logical opinion

Formal thinking tries to fulfill the rules of logical reasoning, and can be contrary to what we consider to be true. Here is a simple logical formal opinion, i.e. conclusion:

(the first premise, the attitude from which we start) Peter is an ant.

(the second premise, the attitude we relate to the first premise) Ants are purple.

(conclusion) Peter is purple.

It is a formally completely correct conclusion, because it is in accordance with the simple form of logically correct reasoning:

since: A = B (phenomenon A is equal to phenomenon B, i.e. has properties like phenomenon B)

and: B = V (phenomenon B is equal to phenomenon V, that is, it has properties like phenomenon V)

follows: A = V (the phenomenon A is equal to the phenomenon V, that is, it has the same properties as the phenomenon V)

Whether it is true is not a matter of formal logic, but of content. Whether the premises are true is not a matter of formal logic.

In other words, when we deal with the form of correct reasoning, the only thing that matters to us is whether we have fulfilled the rules of reasoning.

As far as content is concerned, it is ours to show that a certain premise is true. The determination of truth, however, connects logic with philosophy and special sciences (as discussed in the previous lecture). When everything is taken into account, following only the formal rules of reasoning, we can come to a correct, that is, a logically valid conclusion, which is also untrue. However, formal logical thinking is also part of true conclusions: every conclusion that is true arises from formally correct reasoning, but also from premises that we have determined to be true using appropriate methods.

Therefore, formal logic alone does not always have to lead us to a true conclusion, but in order for a conclusion to be true, it must also correspond to formal rules.

Correctness and truthfulness of opinion

Opinions, on the other hand, are value judgments that express a feeling or attitude. They may or may not be supported by facts. Opinions rely on assumptions and are highly dependent on the perspective of those who hold them. They are also very timely and can change quickly when new information or facts become available. Deep commitment to an opinion does not make it more or less correct.

The fact is indisputable. Facts can be objectively verified and proven with evidence. Facts are not decided by how many people believe in them. These are concrete realities that do not change. Facts are determined by objective, not subjective measurement. As the evidence mounts, the facts become irrefutable. Over time we admit the facts. We do not create them.

The truth of an opinion depends on the fulfillment of the criteria for accepting knowledge, on the fulfillment of the criteria of all theories of truth (reliability of knowledge) and the connection between opinion and truth.

The connection between opinion and truth depends on opinion, which is first based on truth/facts and then changed. Truth does not change; opinion, however, usually changes over time. Therefore, the truth remains, no matter how convincing an opinion is.

Truth is created by people to describe how things really are. They are best described as a state of belief that is thought to represent a universal reality. We decide which truths we are willing to believe. Truths do not have to be logical or verifiable. Like-minded people simply have to be divided. They can arise from faith, devotion or experience. When like-minded people agree on a given reality as things are, then the truth emerges.