# Précis of epistemology/Reason, a manual
## Learning through reasoning what good principles teach

Science (or knowledge) is to give good proofs.
A good proof is a good observation or a good reasoning.
A good reasoning starts from good premises to arrive at a good conclusion by a clear and logical path.
Good premises are good principles or good observations, or conclusions already drawn from good reasoning.
Good conclusions are the statements or thoughts that help us to think well and to live well, the fruits of reason. A thought is a fruit of reason when it helps us to think well and to live well. What is well thought helps us to think well. What does not help us to think well is not well thought.
Reasoning reveals explicitly what principles implicitly determine, it develops what is enveloped, it unfolds what is folded, it unveils what is present but hidden until we have reasoned.
To reap the fruits of reason, we must learn through reasoning what good principles teach.

## Ethics is fundamental to all sciences

To do a science we must always do it well. Think well, observe well, imagine well, speak well, will well, act well ...
Knowledge that is not good knowledge is not knowledge at all.
Epistemology is the knowledge about knowledge. It is fundamental for all knowledge, because we cannot develop knowledge without knowing how to recognize good knowledge.
Ethics is the knowledge about the good of the spirit. Since knowledge is a good of the spirit, epistemology is part of ethics.
All science is based on good principles. We recognize good principles by their fruits, their consequences which help us to think well and live well. To recognize good principles we must recognize their fruits. Since ethics is the knowledge about thinking well and living well, it is the knowledge which recognizes the fruits of reason. Such a knowledge is necessary to recognize all the principles of science. Ethics is therefore fundamental to all sciences.
Ethics is a science as soon as it gives good proofs, based on good principles and good observations.
Good principles are always good for everyone. If one spirit can reap the fruits of good principles, then all spirits can reap the same fruits. When we look for good principles, we look for a good for all spirits, we put into practice a great principle of ethics: the good of a spirit is to live for the good of all spirits.

## The conditions of possibility of truth

For the truth of a statement to be determined, its meaning must be determined. The same statement can be sometimes true, sometimes false, according to the various ways of interpreting it.
To tell the truth it must be determined. We cannot know anything until we have clearly determined the concepts we use.
A concept can be defined from other more fundamental concepts. For example, a circle is a set of all points, in a plane, equidistant from the same point, the center of the circle. But for this definition to be useful, the concepts of set, point, plane, distance and equality must first be determined.
The most fundamental concepts are concepts that are not defined from other concepts. They are determined either empirically or theoretically.
A concept is determined empirically by determining the set of detectors, measuring instruments or observation devices intended to signal the presence of the concept.
Concepts are determined theoretically by giving principles (axioms and definitions) which enable us to reason with them. The most fundamental concepts are determined theoretically with axioms, the others with definitions.
For example, all distance measuring instruments empirically determine the concept of distance. Axioms which found a geometry determine it in a theoretical way.
In empirical science, we want our concepts to be determined both empirically and theoretically, because we want theories that explain our observations.
The principles of a theory determine a set of truths: theorems, logical consequences of axioms and definitions. These theoretical truths are truths by definition. They result from definitions of concepts. Axioms can be considered as definitions of fundamental concepts.
Any theory, any system of principles, however foolish, determines a set of truths by definition, provided it is non-contradictory. But such truths by definition are not enough to make true knowledge. We want good theories, based on good principles, which reveal their value when they bear fruit.
A remark on the precision of concepts: a concept is precisely determined when the truth of its application is determined in all cases. Such precision is rarely achieved and is not necessarily desirable. Conceptual vagueness, partial indeterminacy, can make the use of concepts more flexible and better adapted to reality. In order for a concept to be used to develop knowledge, it is sufficient that the truth of its application be determined in a certain domain, it does not have to be always determined.

## What do we know about good principles?

Logic: we know all the logical principles (the rules of correct reasoning) or almost, because classical logic is enough to make all the sciences. Non-classical logics are not without interest, but they do not seem to be of fundamental importance.
Mathematics: we know principles (those of the theory of sets of Cantor, Zermelo ...) which are sufficient to found mathematical knowledge. We can prove (Gödel, Tarski ...) that our mathematical principles will never be sufficient to prove all the mathematical truths, that we can always find new principles which prove more, but in practice the principles that we already have are largely sufficient for almost all of our theoretical needs.
Fundamental physics: we do not know all the fundamental laws because we do not know how to unify quantum physics and the theory of gravity (general relativity) in a satisfactory way and because we do not know much about dark matter and dark energy. But our present theories can explain most physical phenomena. We have to question the universe as a whole, the Big Bang, the formation of galaxies, black holes, experiments in large particle accelerators ... to meet their limits.
Materialist sciences: we generally justify our explanations not with fundamental physical laws but with intermediate laws (fluid mechanics, population dynamics ...) that we sometimes manage to justify on the basis of more fundamental physical laws. We can always invent new ways of explaining with new intermediate principles. We cannot know in advance everything we will discover in this way.
Psychology: Fundamental physics does not explain the presence of spirit (the life of a consciousness): there are atoms and void - and spirits? It turns out that the electrical activity of the brains can make the spirit exist, but we do not know why. In practice we try to marry a psychological approach (what we know about the spirit because we are spirits) with a materialist approach (how the brain works).
A great principle of psychology: ee are conscious of ourselves in order to be able to act voluntarily on ourselves in an appropriate way.
Philosophy: we find good principles for thinking well and living well, but we never know everything. We can always invent new principles.
A great principle of epistemology: to know, we have to learn by reasoning what good principles teach.
A great principle of ethics: the good of a spirit is to live for the good of all the spirits.
A great principle of metaphysics: the whole being of a being is its being in a whole, or its being a whole, or both.
Next chapter: How the spirit works >>>