[Dimensio]

Beyond theory there might be a 'law' of nature.

No, "laws" are not "beyond" theories. Laws are a different kind of statement, fitting a different purpose.

But, you stated it yourself, a theory can be discarded. Why would that be?

Typically a theory is discarded when observations occur that directly contradict implications made by the theory.

Could it be that new explanations to observations were found, or measurements proved a theory to actually be wrong?

Yes, this would be grounds for discarding a theory. On the other hand, sometimes the theory might be "wrong" on minor details, but not proven wrong at what it fundamentally explains. In those cases the theory is adjusted to take into account the new information.

If a theory stands a chance of being proved wrong, then it merits to be called a 'speculation' rather than a theory.

By your reasoning, everything in science is "speculation" because absolutely everything in all of science is subject to change should contrary observations occur.

[adorno]

By your reasoning, everything in science is "speculation" because absolutely everything in all of science is subject to change should contrary observations occur.

Not all theories are as flaky as 'evolution'.

[edsheppa]

No, "laws" are not "beyond" theories. Laws are a different kind of statement, fitting a different purpose.

I wonder if that's the best way to look at it. Maybe the difference more quantitative than qualitative. That is, they are both explanations of phenomena but the reach of a theory is much greater than a law. For example, Ohm's Law explains just a little bit but Maxwell's Theory of Electromagnetism explains a huge amount.