Aquascope Facts

The example with algae is about observations, but works just as well for explanation models: One can never be sure that a certain model will give the right explanation, even if it is as the model predicts. There can always exist one or more models that predict the same explanation. If, to the contrary, what the model predicts does not correspond with the explanation, we can be sure that the model is incorrect.

Predictions in an example with mussels

Examle with mussels In the case of the different species of mussels, the prediction from the first model is that if the A-mussels are removed from certain areas there would be no competition and B-mussels can colonize these areas. They will increase in numbers. In a corresponding way, if B-musels are removed, A-mussels will increase in number because of reduced competition.
    If any of these predictions are wrong, then the model is also incorrect. The model states that the distribution of species is dependent of competition, if competition is removed, distribution should also change. If distribution does not change, then the reason for the pattern of distribution cannot be competition.
    The other model gives rise to very different predictions: If the distribution of mussels is dependent of salinity, then A-mussels would probably die because of the lower salinity if they are removed from an area where they are common to the area where B-mussels are common. B-mussels would die in larger numbers than A-mussels if moved to areas where A-mussels are common. This is ncessary, otherwise it is not salinity that has affected distribution.
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