Wrote:
-------------------------------------------------------
>
>
> All I have to do now is get to understand the
> difference between a fact and a theory.
> Now, I thought I was making progress on this -
> then I read Stephen’s comment: A scientific theory
> does not become a fact. Ever.
> At which point I very nearly gave up…
> Then I remembered somewhen reading that a Roman
> poet (or some such) had mooted (I think that’s the
> word I want) the idea of Evolution centuries ago.
> And I think I’m right in saying Darwin’s father
> (Erasmus?) believed in Evolution.
> Then, surely, Evolution (which is now a fact) must
> have at some time in the past been a scientific
> theory.
> So, isn’t this an example or case of a theory
> becoming a fact?
>
> Regards to all,
>
> Alex
>

OK let's get to the next point. An interesting book for you to read is Michael Ruse. 2001. The Evolution Wars. A guide to the Debates New Brunswick: Rutgers Univ. Press.

p. 4-5. And let me tell you that, traditionally, there are three things to which the term evolution applies. First, there is what we might call the very fact of evolution. By this is meant the idea that all organisms-- you and I, cats and dogs, cabbages and kings, living and dead-- are the end result of a long process of development, from forms vastly differrent.. .
Second there is the path or paths of evolution, known technically as phylogeny (phylogenies). here we are dealing with the tracks that evolution takes through time. When did life first occur on earth? When did multicellular organisms evolve from simpler forms?..
Third and finally we have the question of the causes or mechanisms or theory of evolution. What makes the whole process go and work? what drives evolution?
What is its motive force?
***
[BOM]. Maybe this will help. Gravity has always been a fact. However, it took Newton to explain how it worked and Newton's ideas were expanded by Einstein. Similarly Evolution has always been a fact, but Darwin is the one, who like Newton, provided the explanation of how it works. Similarly, scientists like Dobzhansky, Mayr, Stebbins, and Stimson developed the synthetic theory of evolution (using the work of Mendel and others) to extend and clarify Darwin's theory.
****
As you mentioned the idea that evolution was a fact already existed before Charles Darwin. Erasmus Darwin believed in evolution, but he mixed up the three points made by Ruse above

Ruse p. 9. Darwin [Erasmus] made little or no attempt to disentangle the various threads of his thinking. Claims about the fact of evolution were mingled with ideas about the paths of evolution and then threaded through the whole discussion were hypotheses and speculation about the causes of evolution. Quite often he would start a paragrah talking about paths and then end up talking about causes. Or he would start off talking about causes and end up arguing for the general fact. He may have been an innovative thinker; he was no great systematist... .
p. 11 He was a strong supported of the idea that characteristics acquired by an organism in one generation can be passed straight to the members of the next generation. He instanced the docking of dogs' tails. Darwin believed that this practice eventually results in the birth of animals without any tail at all. This inheritance of acquired characteristics is today known as "Lamarckism" after the great French evolutionist of that name.. .
p. 15-16 Darwin believed in a God who was the unmoved mover. he believed in a God who has put things in motion and who then stands back and watches how things work out through the agency of unbroken law. To use the technical language of scholars, Darwin was a deist. as opposed to a theist, traditionally a Christian, a jew, and a Mulim. A deist sees the greatest mark of God's power and forethought in the working out of unbroken law, as opposed to the theist who sees God's power in direct intervention, that is, in miracles. Using a modern metaphor, what one might say is that Darwin's god--the god of the deist-- has preprogrammed the world so that he did not have to intervene further. Evolution, therefore, can be seen as the greatest thriumph of God. It is the strongest proof of his existence.. .
***
[BOM] What Charles Darwin did was 1) to provide overwhelming detailed evidence for the fact[/] of evolution, and as Ruse points out this was rapidly adopted by English society. 2) Darwin did not do very much about the paths of evolution. 3) He provided a convincing mechanism by which evolution had proceeded. The key ideas were valid then and are valid now, but, because knowledge was not available then, Darwin's ideas about how traits were transmitted were wrong and that is what was corrected in the "modern synthesis" (chromosomes, alleles, DNA, etc).

Hopefully this helps.
Bernard