Perhaps I'd better answer Steve Shaw's question before this thread drops off the bottom

Do tell us if you're not completely certain that evolution happens.

No, I am not completely certain that evolution happens because I take a scientific view of the world, not a pseudo-religious one. Science doesn't do "completely certain". I can't agree with "Evolution is true" because, as others on this thread have pointed out, science doesn't do absolute truth.

Part of the problem is that you are rather flexible in your use of the word evolution. Frequently you have used it interchangeably with Darwin's Theory of The Origin of Species by Means of Natural Selection while lambasting others (well, me) for doing the same. No real worry, everybody does that. "The Theory of Evolution" is generally taken as a shorthand for Darwin's theory.

You have also referred to it as a "concept". I think I'd go along with that.

Darwin refers to "species undergo modification, and that the existing forms of life are the descendants by true generation of pre-existing forms.". Sounds like a definition of "evolution" to me. (Does Darwin ever use the word?) It says nothing about the reasons for those modifications, just that it happens. Does that do it for you?
As best as I can understand, the point you are trying to make is that it is a natural phenomenon like the sun, moon or stars or gravity or, indeed, you having a shit. There for you to see if you care to look. The trouble is Darwin doesn't seem to agree. Here is the fuller context for that quote -

I will give here a brief sketch of the progress of opinion on the Origin of Species. Until recently the great majority of naturalists believed that species were immutable productions, and had been separately created. This view has been ably maintained by many authors. Some few naturalists, on the other hand, have believed that species undergo modification, and that the existing forms of life are the descendants by true generation of pre-existing forms.

(Opening lines of "AN HISTORICAL SKETCH". Page 53 in the Penguin Classics edition of Origin of Species.)

It seems that Darwin does not agree with you. It is not something obvious and, in the mid-nineteenth century, a new and revolutionary idea not widely held. He then spends several pages presenting the case, not from scientific logic but by quoting the works of others. This is not his idea, but the starting point for his theory which is an explanation of what drives that process - Natural Selection.

So, Steve, if you think you know better than Darwin, carry on shouting "Evolution is true!" to the rafters.

Now do go along and shove your philosophical carpings where the sun don't shine, dear boy.

Sigh. I really was hoping for some response from you to Stu's remarks a while ago -

what is important is understanding what science is and how it works, and you don't need to be a scientist to know that. You do have to get off your arse do some work though to familiarise yourself with the philosophies and methodologies that make 'science' what it is, and explains how it's come to be practiced as it is and how it changes with time.

By brushing aside "philosophical carpings", you are underming Stu's case against pete. Whose side are you on?