Scientific laws

Laws of nature

A topic in  Learners' conceptions and thinking

A common alternative conception is that a theory is something which has the same status as a guess, opinion and hypothesis.

Learners often think that when theories are tested, science can prove them, in which case they are factual, so no longer theories. They may become seen as laws (Taber, et al, 2015).

Student understandings of scientific epistemology were generally simplistic. For most interviewees theories were just ideas, until they were proved to be correct.
Student understandings of scientific epistemology were generally simplistic. For most interviewees theories were just ideas, until they were proved to be correct. (From Taber et al, 2015)

Students seem to commonly think that something with the status of a scientific law has been (strictly) proven.

Scientific knowledge, however, is seen as conjectural, and in principle provision (open to being revisited in the light of new evidence of new ways to think about evidence).

Laws cannot be proved

Scientific laws, or laws of nature, must logically remain conjectural (even if sometimes the evidence supporting them is extensive) as they are generalisations across wide classes of phenomena. The generalisations derive form observations across many instances that have been investigated, but it is never feasible to test all instances where the law would apply.

For example, Newton's law of Universal gravitation claims that every mass in the universe is attracting every other mass (not only that, but with a force that can be calculated by a strict numerical formulae). Clearly, it is quite impossible to test the law sufficiently to prove it is true. Clearly, it is quite impossible to test the law in more than the most tiny proportion of the cases that occur!

Some laws are never 'obeyed'

Indeed some scientific laws are ideal. The ideal gas law only applies to ideal gases (which would be those where the molecules of the gas had no volume at all, and where the molecules did not interact at even when extremely close to each other). There are no ideal gases, so the gas law applies fairly well to many substances over part of the temperature range where they are gases.

Raoult's law is another example of an ideal gas, as it is only strictly followed in mixtures where the molecules of the components interact with their own kind in exactly the same way they interact with molecules of other components. (There are probably no mixtures where that is precisely the case.) Real mixtures show deviations for Raoult's law.

Work cited:
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