Conversely, I can easily use the word "unoriginal", but try to be sensible, empathic and plausible while doing that. As, my experiences proved long ago that some "similarities", and even virtually identical productions can be the results of sheer coincidences.

Fun trivia: People liken me (slightly physically, but more in terms of character, temperament, and way of thinking and talking) to Sheldon Cooper of The Big Bang Theory, and I swear that I haven't watched even an episode of that TV series. (I had to do a Google search to write the name here.) A friend of mine gave me the link of a YouTube video composed of its best scenes where Sheldon Cooper acts, only last year. I still am not interested, haha.

Anyway, I believe all of us can give countless similar examples, but my actual point is that; in order to be sure of whether something is unoriginal or not, we also have to be sure that the creator of an output -which can be deemed as unoriginal- is/was aware or unaware of the "original" thing that s/he is accused of ripping off.  This shouldn't necessarily mean that we cannot "accuse" anybody of this. For instance, if a metal band do a very similar song to Metallica's one big hit, they cannot/shouldn't easily get away with that... Come on... You must be aware that such a song exists!

Any thoughts/insights/arguments?

Very easy. Originality is something that hasn't been done before. The magnitude of which can vary greatly.

The problem with defining something as original lies in the fact that evolutionary processes are gradual incremental developments.

Occasionally a big bang of creativity can occur but more often than not it is a result of subtle changes of what has been done before.

So what's the point?

There is a chance it is actually a case of deliberate musical plagiarism. There is also a chance it is a case of unintentional musical plagiarism; if the musician perhaps heard the original source music, forgot about it to some degree, and then used it thinking it was original. There is a chance the musician never heard the original, but heard many similar, either preceding or derivative, pieces of music, and came up with something almost entirely similar.

I remember a long time ago that a band from my hometown came out with an album in the same year as Pearl Jam’s Vitalogy. In fact, it was released before Vitalogy. And one of the songs on it has pretty much the exact same repeated refrain as Last Exit. There’s no way either band heard the other’s song. Sometimes incredible coincidences just occur. People jump to the idea that something is derivative or plagiarised, and while that is probably the case eight or nine times out of ten, it is most certainly not always the case.

I would agree that I would expect a metal band to have heard this one big hit, but suppose a band of another genre created a song using a similar riff and claimed they had never listened to Metallica - how would you prove otherwise?

I sense, implicit to “originality” as it’s being used in this thread, the idea of an isolated artwork or idea, having nothing to do with what has come before. I think that’s sort of the artistic equivalent to the idea of ‘spontaneous generation’ in the realm of science; in other words, loaded thinking without basis in reality.

I looked up 'Original' in the dictionary and this is what I saw...

SteveG wrote: There's nothing new under the sun. Most of the time.

As pretty much nothing is exactly equal to anything else, everything is new all the time, at least to some extent.

Also, all meaning depends on context, so if somebody does the same stuff that somebody else has done before in a new context (and all contexts are to some extent new), it's not the same anymore.

Regarding the term "original" it doesn't matter that much. Be it that nothing is new, be it that all is new, is doesn't  have much distinguishing power either way.

From my personal point of view, I can very well distinguish between what seems generic to me and what has an "original wow factor". I'd call things original that make an original impression on me, but of course I know that I don't know whether one can in fact find these ideas earlier elsewhere, and whether they 'd have impressed me in the same way, had I heard or seen the earlier version first. For my perception that's not very important, but of course I shouldn't use the word in a supposedly objective manner. Who am I to claim that I know all stuff? I may do it when I believe I know quite a bit, but it's always taking a risk.

Then, also claiming that something is "unoriginal" (based on not being of original interest to me) can go wrong, as I may miss some detail or context and may not get that there's actually more in it than what I find.  

Remember music is not music anymore.......

This is a very difficult topic to discuss. The main reason why is because of the media and the very fact that we can hear so much these days, as to make it almost "impossible" to think or feel that you can create something original.

Having worked with actors on these things, I sincerely doubt that "originality" is something that you can bottle up, and it relies on each and every person for its interpretation and eventual showing. And here is the worst part of that ... the fact that we do not listen to music, or appreciate the arts, for what they are ... INSTEAD WE COMPARE THEM TO WHAT WE LIKE AND KNOW ... ignoring what we don't know, exclusively.

There was one example on one of Peter Brook's books about Keith Mitchell when he did King Lear ... and it was scary for many of us, and our ability to understand that is impossible given the listening habits we have here ... there is a repeat line in KL that has "here" said 4 times in a row, and PB said that Keith did over 200 performances and not once did he ever repeat himself ... each night when doing his thing.

AND THIS, speaks of something else that we do not believe to be "original" because we CAN'T FEEL IT, or UNDERSTAND IT ... we do not know how it was that he could do that, and on top of it how he could so easily match it every night to the rest of his words and performance ... and KM would say ... don't ask ... I don't know!

Mostly, what could be said was that he got into the character each night, and today is not yesterday and the use of the words would be different ... but since we do not know any "justification" or have any "understanding" of how it happened, we can not make up our minds about it ... and think it is just some weird this or that ... when it has more to do with the person's identification of the feeling in that moment than anything else.

This brings up a great point about "originality" that is over looked ... when we do not know or can not "feel" what it is that is going on, and this is a serious issue with listening to many foreign bands here at PA ... you don't understand what Vittorio, or Christian, or someone else is saying ... and it alienates you, because you feel left out ... meaning that the likelihood is that you do not like to feel apart from that music, but the band presented it in such a way that does separate you from it. 

"Originality", and specially when involved in the "newer" strands of artistic representation (not just music, which is the worst of the big 3 arts!), gets lost in the wording ... because many can not define it ... but we refuse to look at how Stravinsky dealt with it, how Picasso dealt with it, and how many others dealt with it during their time, when in essence their expression was "personal" (most important) and not something that everyone else does ... and obviously copies.

I have never felt that anyone copies anyone, although people here have the awful habit of comparing bands because they use the same instrument, which automatically makes them a "copy" of some (supposed) original group ... and that has a tendency to diminish the artist's work to just sound ... when all that instrument could do was sound like that.

Until such a time as we stop "comparing" stuff, and learn to appreciate ALL music, I sincerely doubt that we can achieve a nice and complete idea as to what we are really listening to ... and this is specially difficult when most folks are strictly using their "filters" for what they like and don't like ... and not giving the work a chance to live on its own.

But a consensus about this is hard ... because this is a social media crapper and I sincerely doubt that most folks can "forget" all that and say something constructive about the whole thing that makes sense, instead of personal comments ... which I think get really boring after a while.