How do we individually acquire knowledge? Some of what we know comes direct, through our own sense experiences and thought processes. For example, we all have direct knowledge of the place where we live, but there will probably be many other places we have never visited and of which we have only second-hand or indirect knowledge. Probably the majority of our knowledge is second-hand. We rely upon what various authorities tell us. Many of us tend to be lazy and just go along with what people in authority tell us without properly questioning what they say. It is therefore very important for us to be able to know how much trust we can put in their pronouncements. For many people trust is a simple matter of assessment of the character of the person. Unfortunately unless we really know the person closely we can easily be deceived. How often do we read in the newspapers of naive people being conned out of their savings by convincing rogues, or led astray by charismatic leaders? A second way to assess trust-worthiness is through consistency. If the ideas hold together in a logical manner without contradictions then we can say they make sense. A third way is to seek other opinions.
How do each of us, individually, know what is true and what to believe? The only sound answer is that we have to rely on our faculty of reason. All humans have the ability to reason, that is to think for ourselves, we need it just to survive from day to day. There is no reliable alternative. Reasoning is not difficult, it is largely common sense. It is what we do when we add up our shopping bills, or when we look both ways before crossing the road.
To use a term from computing, rationalism is the default position. Any other claims for knowledge not based on rational investigation are optional extras. Where they violate reason they are fictions or delusions or romantic fantasies. Where they lie within the bounds of reason (which are not completely determinate) they amount to lifestyle choices, which include ethics where the best choices can be determined by reason, aesthetics where choice is a matter of personal whim and cannot have an adverse affect and politics where choices can have considerable effect but it has not yet become possible to scientifically demonstrate which choice is the best.
The basis of the collective knowledge of the human species is the scientific method. How does this work? Simply expressed, it is a cyclical process:
Well known examples of scientific theories are those of Gravitation, Evolution, Relativity and Quantum Mechanics. This process of establishing knowledge is a virtuous spiral, a repeated process, that brings us ever more sure knowledge but can never provide absolute certainty, which is an impossibility. Of course in practice the application of such methods is not always straight forward. Imagination and opportunism are often needed. Many of Pasteur's experiments are regarded as models of scientific method, but he did not ignore the element of luck, he wrote: "Chance favours the prepared mind".The need for scepticism must also be emphasised. Scientists are human and fallible. The method of peer review used by reputable scientific journals is intended to prevent errors being published, but may become a too cosy club of like-minded reviewers. It is advisable to also check the views of independent mavericks and of those in related disciplines. Experts have been known to be wrong. This may be because their ideas have become out of date and they have not adapted to new information, or it may be that their scientific ideals have become compromised by their paymasters or by their allegiance to fixed ideologies. Ultimately, there is no substitute for the onerous obligation to use our own brains and learn to think for ourselves.
I would emphasise that scientific knowledge is not cold and unemotional. It can give us an awesome picture of the universe, vast in space and time, both simple and complex in structure, with both beautiful and horrific aspects.
Philosophy, literally 'love of wisdom', is simply thinking carefully about any subject, starting from the basic facts and trying to put them into some sort of easily understandable pattern, governed by overarching general principles. Much of the early 'Pre-Socratic' philosophy of the ancient Greeks was of a speculative nature that we would now call 'Metaphysics' or even 'Fantasy' because it was insufficiently based on first ascertaining the empirical facts of the subject.
Pure thought, with only limited empirical input, can lead to worthwhile knowledge, since this is the basis of logic and mathematics. It has often been the case that structures studied by mathematicians have subsequently proved useful in describing structures found in nature. The Greek development of geometry, as expounded by Euclid in the Elements was one of their greatest achievements.
The need to combine philosophical thought with observation and experiment, became known as 'Natural Philosophy' in the renaissance. The principles were expounded by Francis Bacon and the members of the first scientific societies, around 1600. The motto of the British Royal Society, founded in 1660, is 'Nullius in Verba', meaning no empty arguments unfounded on empirical facts.
Natural philosophy became 'Science' in the 19th century. Scientific explanations of phenomena are based on observations and experiments that can be substantiated by others. Progress in science consists of the development of better explanations of the causes of natural phenomena. They are never complete and final and may be rejected in the light of further observations or experiments. Recent, but still controversial, works of philosophers and scientists on scientific method include the following:
Karl Popper (1902 - 1994) in The Logic of Scientific Discovery (1934) re-examined the problem of induction and placed more emphasis on the development of theories through imagination and speculation than from observation. From this perspective it is the falsifiability of a theory that makes it properly scientific rather than its verification from observation. An objection to this view is that surely an observation that falsifies one proposition verifies its negation. Another is that theories can be multiplied without end, and induction from instances is needed to keep our imaginations in check.
Thomas Kuhn (1922 - 1996) maintained in The Structure of Scientific Revolutions (1962) that science at any one time has a dominant world-view which tends to change in a revolutionary manner called a paradigm shift. The works of Copernicus which put the Earth in orbit round the Sun, and of Einstein on general relativity are prime examples. The consensus view however seems to be that these revolutions develop gradually and are only accepted after a struggle, and that most of the pre-existing paradigm (i.e. Earth-centred astronomy, and Newtonian mechanics in these two examples) is still useful within the new framework, and progress is cumulative rather than revolutionary.
The literary, sociological and religious ideas of Post- modernism, developed by a wide range of thinkers, have attacked traditional views of science and of truth. The famous hoax paper by Alan Sokal illustrates many aspects of this.
It is often held that reconstructing the history of the past cannot be truly scientific because it can never be confirmed by direct observation. However, it is also true that many other concepts of science have not been observed directly, for instance black holes in astronomy and quarks in physics, and for many years the existence of atoms was fiercely disputed. We deduce their existence from phenomena to which they give rise. The same is true of the past, we deduce it from clues that remain in the present, from written documents, to archeological remains, to fossils, to chemical and physical changes in the rocks.
Our knowledge of the past, like any other knowledge, is based on gathering evidence. For history we rely on documents, for archaeology on material artefacts, for earlier evolution on fossils. Many of the claims of faith rely on gaps in our historical knowledge. As there are no independent accounts, outside the Bible, it is doubtful if the lives of such characters as Moses or Jesus are anything other than myths of the same nature as the stories told about King Arthur or Robin Hood. Claims that religious books like the Christian Bible, the Muslim Koran or the Hindu Vedas are 'the words of gods' are mythical nonsense, like any other books they were written by men.
Does belief differ from knowledge? For most people belief is knowledge that is imbued with feeling to some degree. This applies especially to ideas that affect our lives closely and which we may need to access quickly to make decisions. I take the view that feeling underlies the operation of the human faculty of reason. The way it works, I think, is that in deciding whether to believe a statement, especially one that is going to affect our lives closely and on which we may need to take a decision, we weigh up in our minds, possibly subconsciously, our feelings for and against the subject. Think of the symbol of the scales of justice. If our positive and negative feelings on a subject balance and are not too strong we don't particularly care one way or the other about it. If the positive feeling outweighs the negative we accept it as part of our beliefs. On the other hand if we have strong feelings both for and against, this may result in emotional turmoil. This may happen for example if we get opposing advice from our parents, or from a parent and a valued teacher.
When the feeling associated with a belief is strong enough to amount to an emotion we can talk about believing in something. It is then a motivational commitment.
Belief as above defined is rational, it is based on evidence. This is in contrast to faith, which is emotional belief in something without sufficient reason. It is irrational belief, wish fulfilment.
Logic is a special form of reasoning in which we set out our assumptions and proceed from them to our conclusions in a simple step by step procedure. If each step can be agreed to be correct then the whole chains of reasoning must be accepted as true, and it must be accepted that our conclusions do indeed follow from our assumptions.
Some links to sources on the logic of fallacial arguments