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"What can be asserted without evidence can also be dismissed without evidence."
The fact that only real knowing entails this experience at this moment does not mean that "normal" knowledge is not possible, or else life would be insurmountably difficult. Logical reasoning and the scientific method do produce results and usually make sense.
What does not make much sense, at least as far as I am concerned, is speculation, especially metaphysical or "spiritual" speculation.
Speculation is a form of entertainment, a non-serious play at best, not truth. "Life after death" or "universal consciousness" - no one knows or can know if these are real or not, no matter what they tell me. I can choose to believe these things. But belief is not knowledge, not even "relative" knowledge.
However, some forms of imagination have a solid, reliable foundation and can therefore be used well in everyday life, be used as a source for predictions or serve as a basis for developing technology. So we call this kind of imagination "knowledge". Reliable knowledge exists when there is sufficient evidence for it.
Considering the arithmetic sum of the natural numbers 5 and 3, I seem to "know" that it is 8. Do I really know that? Surely not in the same way as knowing this moment. With knowing this moment I don't have to think. For the arithmetic operation, even though very short, I still have to think for a moment and use my memory. It is not a direct, immediate knowing.
A lot of the knowledge of arithmetic operations is implicit. It presupposes a lot of science, which I no longer think about - because it has become so familiar. When I was about 5 or 6 years old, it took a lot more effort and I had to actually count the sum in my head. The rules of arithmetic had not been fully absorbed then and had yet to be consciously consulted.
This is also similar to the implicit knowledge of how to ride a bike or how to swim. These are activities we have learned. After a while, our body "knows" how to do that and one doesn't think about it anymore.
So it seems like we know certain things for sure, but in fact that knowledge still comes from memory, even though we no longer have to consciously think about it.
I can imagine all kinds of things and have all kinds of things foisted on me, but which imagination, which assertion is correct and which is not or less correct?
Assertions can be trusted if sufficient evidence for the correctness of the assertion can be provided. The correctness of an assertion will always be relative. Absolute proof is not possible and not needed, but it must at least be sufficient (for now) for effective decisions to be made based on the assertion.
The factuality of sense perception per se is, as far as I am concerned, beyond question. The correctness of the interpretation of what is observed is not. Perhaps it is a hallucination or a dream. So some skepticism is in order. Of course, everything can be doubted (except the fact of doubt when doubting), even direct observation (leading to the position of "radical skepticism"). But in practice we don't do that, because it wouldn't really be convenient in daily life or scientific practice. On the other hand, you can also just be wrong. So between seeing something and recognizing, or putting into words, ultimately naming what you see, a process of interpretation takes place, that is, memory is consulted and an attempt is made to make the best possible "match" with previously acquired knowledge. The interpretation can then be more or less effective. You think you see a snake, but it is in fact a piece of string. Oops.
But if I see something in my world that looks like an apple and I have no reason to believe that I am hallucinating, dreaming or making a mistake, I really don't see any problem eating that apple. With direct perception, normally, no explicit evidence is needed. Then perception can be the evidence.
Sufficient evidence can further be obtained in the following ways:
Proof by logical derivation. Take a simple theorem that can be derived by simple logic (a modus ponens, for example):
Right as pie. No question about it.
In formal logic, provability is an automatic event based on the correct execution of a set of rules that can be derived from the axioms of the system. In formal logic, then, provability is not the same thing as truth. To characterize something as true requires checking with reality. And further, we have known since Gödel that no formal system can be derived completely from its axioms. There will always be propositions that are not provable, but may well be true…
Anyway, as long as we do not have to assume a formal system, but simply our "common sense", a valid, logical formulation is sufficient to characterize something as knowledge.
Evidentiality through the scientific method. In science, the procedure of the "empirical cycle" is usually followed to arrive at scientific knowledge. This cycle is applied to gain knowledge from experience, by means of constructing hypotheses and testing them. This is often done in the natural sciences but also in psychology through experimentation.
The scientific method is a systematic way scientists use to investigate and understand the world around us. It involves a series of steps to gather evidence, test hypotheses and draw conclusions.
First, scientists begin with observations or questions about something they want to understand. These observations help them form a hypothesis, an informed guess about how things work or why something happens.
Next, scientists design experiments or collect data to test their hypotheses. They carefully control the variables to make sure their results are reliable and repeatable. By collecting and analyzing the data, scientists can determine whether or not their hypothesis is supported.
If the data support the hypothesis, scientists can repeat the experiment several times to confirm the results. They can also share their findings with other scientists through scientific journals or conferences.
If the data do not support the hypothesis, scientists go back to the drawing board and revise their ideas. They may come up with a new hypothesis and set up new experiments to test it. This process of revising and refining hypotheses is an important part of the scientific method.
Thus, scientific knowledge is obtained in this way, which can be constantly modified as new facts become available.
"[…] even results that are referenced and published can be wrong. […] I want to emphasize that science is not just a set of results handed down from above, it is a process. We can be wrong. We make assumptions, hypotheses and guesses, and we go and find out whether they work or not. And that's not a mistake, it's a feature. That's how science works."
Theoretical physicist Sean Carroll
An example of reliable scientific knowledge is the Theory of Evolution. The evidence for the existence of evolution is extensive and comes from a variety of scientific disciplines. Here are some key pieces of evidence:
Fossil record: The fossil record provides a wealth of evidence for evolution. Fossils demonstrate the existence of many extinct species and provide a record of transitional forms linking different groups of organisms. For example, the discovery of transitional fossils such as Archaeopteryx, which exhibits characteristics of both reptiles and birds, supports the idea of the evolution of birds from reptilian ancestors.
Comparative anatomy: Comparative anatomy involves studying the similarities and differences in the structures of different organisms. Evolutionary theory predicts that species with a common ancestor will have similar structures. Homologous structures, such as the pentadactyl limbs (limbs with five fingers) in humans, cats, whales and bats, provide evidence of a common ancestor.
Embryology: Embryology, the study of embryonic development, reveals similarities in early developmental stages in different species. For example, the embryos of fish, reptiles, birds and mammals show similar features during early development, including gill slits and tails. These similarities indicate a shared evolutionary history.
Molecular Biology: Molecular biology provides compelling evidence for evolution. DNA sequences allow scientists to compare genetic information from different species. The more closely related two species are, the more similar their DNA sequences are. By analyzing DNA, researchers have identified shared genetic sequences and inheritance patterns that support the idea of common ancestry.
Biogeography: The distribution of species across different geographic areas supports the concept of evolution. The existence of closely related species on nearby islands or different continents suggests that they evolved from a common ancestor and then grew apart as a result of geographic isolation.
Observable evidence: Scientists have observed instances of evolution occurring in real time. For example, the evolution of antibiotic resistance in bacteria is well documented. In response to antibiotic use, bacteria may undergo genetic changes that allow them to survive and reproduce, leading to the emergence of resistant strains.
These are just a few examples of the evidence supporting the existence of evolution. The cumulative evidence from various fields of study provides a solid foundation for the theory of evolution, which is widely accepted in the scientific community.
Another example is the Standard Model of particle physics. The Standard Model describes the smallest particles in our universe, and the forces of nature acting on them. The accuracy and thus success of this theory is nothing short of astounding. For example, the theory's prediction for the measured value of the fine structure constant has an accuracy of 1 in 109 ! At the same time, physicists are quite sure that this theory is not, or cannot be, complete because certain phenomena in particle physics cannot be explained by it.
Thus, a true scientific theory is not "just a theory". Theories such as the theory of evolution and the Standard Model by now have earned the status of being factual and are considered extremely reliable knowledge. The same thing cannot be said about for instance "creationism". Creationism is clearly not science, not knowledge, but religeous belief, because there is no proof at all!
We will see later, however, that scientists are also only human and thus prone to prejudice and can be just as much a victim of completely illusory (and unconscious) imagination.
Anyway, as long as we keep our questions and thus our answers practical and pragmatic, there is usually no problem. Problems only arise when one keeps on questioning further. After all, you can always ask further. Until one reaches the limits of knowledge. Beyond this limit, no provable answer is possible and we have arrived at pure speculative "anwers" to so-called ultimate questions like "what is mind?", "what is reality beyond experience?" or "why is there a universe?". When answering those kind of questions anyway, rational reasoning has ceased. We are then in the realm of metaphysics, religion, belief. Some will say that these are the questions that really matter. Others will shrug their shoulders.
Answers to ultimate questions, believed to be definitive, are legion, but will always be and remain only hypotheses and are therefore, if believed, a form of self-deception.
In other words, as soon as answers to ultimate questions are found and those answers are accepted as truth, knowledge disappears and belief emerges.
Several ultimate questions and their "answers" will be investigated later on.