Theory/Model - Prior to new experimental evidence, this can be viewed as the initial state of the cycle and represents the relevant knowledge (hypotheses, theories, models, etc.) that is to be tested. After the experiment has been performed, this can be viewed as the final state that represents the (possibly conditioned) relevant knowledge as modified by the new experimental evidence.
Deduction/Simulation - This action represents the process of exercising the logical/mathematical consequences of the theory/model in order to yield a consequence capable of being experimentally tested.
Prediction/Forecast - Based on the prior theory/model, this state represents some sort of explicit statement of what the outcomes (observations/results) of the experiment are predicted or forecast to be.
Experiment - This action represent the actual setup and performance of the experiment in order to test the predictions/forecasts.
Observations/Results - This state represents the evidence (facts/data) acquired by the experiment.
Abduction - This action represents the process (logical induction) of modifying/replacing (if necessary) the prior theory/models to make them more consistent/agreeable with the latest experimental evidence.
IV&V - These actions performed by independent stakeholders (Independent Verification and Validation) take place throughout the cycle. These quality assurance processes (such as peer review) are necessary to reduce the risk of error to an acceptable level.
The fundamental assumptions upon which the scientific method rests (that is, that which is more-or-less undefined and simply taken on faith by all stakeholders) are approximately:
- Theory shall be logically consistent. (For example, the interpretation of experimental evidence as Bayesian.)
- Theory and experiment shall be parsimonious. (For example, Occam's Razor.)
- The sole test of theory shall be experiment. (Feynman's 'almost' definition of science.)
- All experimental processes and evidence shall be independently verified and validated.
Why these assumptions? The first assumption is necessary to promote rational discourse about science. Otherwise, consensus is unobtainable. The second rule is 'merely' practical and helps control error and makes IV&V easier. The third rule is the most fundamental one and key to any process being labeled as 'scientific'. The fourth rule is needed only to the extent that fallible beings are used to conduct science.
Note that even this most bare form of the scientific method contains two logical fallacies. The first is the use of abduction (affirming the consequent). The second is the partial reliance on IV&V for error management (appeal to authority). The use of abduction eliminates logical certainty from the scientific method and introduces the possibility of error. The logical shortcoming of IV&V means that finding and eliminating error is never certain.
Also available is a Bayesian version of this approach to the scientific method.