A threefold classification of useful knowledge is provided as:
- Objective knowledge.
It will be taken as self evident that a body of knowledge cannot be established with absolute certainty but arguments can be presented to support it and it can be criticised. However it is extremely important not to embark on a futile search for ultimate justification and certainty that would lead to a frozen body of eternal truths. Knowledge growth is an evolutionary process. Knowledge is not something which can be stock-piled like gold bars, or mature in a barrel like wine – it is speculative, fallible and volatile. The evolutionary explanation of knowledge growth has been concisely described by Popper (Conjectures and refutations. Routledge and Kegan Paul, London, 5th edition, 1974.).
The way in which knowledge progresses, and especially our scientific knowledge, is by un-justified (and unjustifiable) anticipations, by guesses, by tentative solutions to our problems, by conjectures. These conjectures are controlled by criticism; that is, by attempted refutations that include severely critical tests. The conjectures may survive these tests; but they can never be positively justified: they can neither be established as certainly true nor as ’probable’ (in the sense of probability calculus). Criticism of our conjectures is of decisive importance: by bringing out our mistakes it makes us understand the difficulties of the problem which we are trying to solve. This is how we become better acquainted with our problems, and able to propose more mature solutions: the very refutation of a theory–that is, of any serious tentative solution to our problem–is always a step forward that takes us nearer to the truth. And this is how we can learn from our mistakes.
The process of testing and, trail and error provides the knowledge obtained in this way with an objective status and practical reliability that cannot be obtained by firmly held belief. But not infallibility and therefore in practical application alertness to the possible failure or need for correction to the knowledge must be maintained. This gives rise to a knowledge growth life-cycle model shown in the figure above. In this model the cycle starts with the recognition of a problem or a challenge that needs a solution. For example this can come about through contradictions or incompatibilities in the pool of knowledge. A current clear example of this is the incompatibility of General Relativity and Quantum Mechanics.
There is no mechanistic process for creativity but it is mandated that creative outputs should be testable in principal. Testability is a logical requirement on the formulation of a theory or an explanation because If a solution is not testable then it is independent of what is the case in the world and therefore irrelevant to explaining what is the case. The reason why only testability in principal should be mandated is that a new explanation or solution can itself suggest new measurement or test methods and therefore provides a new problem in how to realise the test. This can be done because testability is part of the logical structure of an explanation and does not require specific tests to be put forward initially.