<P> Attempts to formalize the principles of the empirical sciences use an interpretation to model reality, in the same way logicians axiomatize the principles of logic . The aim of these attempts is to construct a formal system that will not produce theoretical consequences that are contrary to what is found in reality . Predictions or other statements drawn from such a formal system mirror or map the real world only insofar as these scientific models are true . </P> <P> For the scientist, a model is also a way in which the human thought processes can be amplified . For instance, models that are rendered in software allow scientists to leverage computational power to simulate, visualize, manipulate and gain intuition about the entity, phenomenon, or process being represented . Such computer models are in silico . Other types of scientific models are in vivo (living models, such as laboratory rats) and in vitro (in glassware, such as tissue culture). </P> <P> Models are typically used when it is either impossible or impractical to create experimental conditions in which scientists can directly measure outcomes . Direct measurement of outcomes under controlled conditions (see Scientific method) will always be more reliable than modelled estimates of outcomes . </P> <P> Within modelling and simulation, a model is a task - driven, purposeful simplification and abstraction of a perception of reality, shaped by physical, legal, and cognitive constraints . It is task - driven, because a model is captured with a certain question or task in mind . Simplifications leave all the known and observed entities and their relation out that are not important for the task . Abstraction aggregates information that is important, but not needed in the same detail as the object of interest . Both activities, simplification and abstraction, are done purposefully . However, they are done based on a perception of reality . This perception is already a model in itself, as it comes with a physical constraint . There are also constraints on what we are able to legally observe with our current tools and methods, and cognitive constraints which limit what we are able to explain with our current theories . This model comprises the concepts, their behavior, and their relations in formal form and is often referred to as a conceptual model . In order to execute the model, it needs to be implemented as a computer simulation . This requires more choices, such as numerical approximations or the use of heuristics . Despite all these epistemological and computational constraints, simulation has been recognized as the third pillar of scientific methods: theory building, simulation, and experimentation . </P>

The three key aspects of the overall scientific enterprise include all of the following except