Well, that explains everything.
I’ll explain. A friend (Doug Linzey to be precise) suggested I taste this word. So of course I looked it up, not just what it means – it’s made of well-known parts anyway – but what and who brought it forth. And I found a bunch of links to articles and tweets attributing it to Karl Popper, the philosopher. And one link to a Wikipedia on Ernst Pöppel, a neuroscientist. But when I clicked through on the article, the word was not to be found – vicitim, I suppose, of some recent edit.
So I searched monocausotaxophilia Pöppel. And I found what I suspected: Ernst Pöppel invented the term. Thing is, he’s not very well known to the world at large; Karl Popper is somewhat better known (not least, I’m sure, because his name makes many people think of popcorn). So some people saw Ernst Pöppel and misremembered it as Karl Popper, because that was a path of less resistance. His name was more familiar. And it was plausible: he’s a philosopher, and in particular a philospher of science who argued against inductivist and justificationalist approaches to science (ironically, given the misattribution of the quote to him) and in favour of what is now accepted as standard scientific method: keep making experiments, and you’ll have more and more evidence for something, but you never know for certain that a generalization is true, you just know when it’s been proven false. So anyway, a philosophical thing a neuroscientist said could readily be misattributed to a philosopher of science.
And what I’m getting to is that this tendency to misattribute quotes to whichever person has the maximum combined fame and appropriateness (seriously, I think most quotes are more often attributed wrongly than rightly) tells us enough about the way people think that it can also help us to understand how words are formed and altered. For instance, internecine comes from Latin neco ‘I kill’ plus inter, which – like several other prefixes – served as an intensifier. It meant, originally, ‘killing them all’ or ‘thoroughly deadly’. But people saw inter and recognized it as a prefix that they were used to meaning ‘between’ or ‘mutual’ and so its sense became ‘mutually destructive’. The meaning swerved over to the track of least resistance.
Quite a few words have shifted sense on the basis of their sounding more appropriate to another sense because of other things they sound like. Some words have had their use affected in other ways – if a word sounds too much like a word we want to avoid, we tend to avoid that word too, even if its sense and origin are unrelated (I’m sure there’s some suitable remark about mutual destruction I could make here). And we also break words apart where it sounds best to us rather than at the places they were originally joined together, which is why we say copter rather than pter and shopaholic rather than shopcoholic.
All of this also tells us why we have a word such as monocausotaxophilia. Have a look at its bits: mono from Greek μόνος monos ‘alone, single’, taxo from Greek τάξις taxis ‘order’, philia from Greek φιλία filia ‘love’, but causo from Latin causa ‘cause, reason’. These are all parts of the lexical Lego bucket, but from two different sets that have been combined. It just happens that the Greek equivalent of causa, αἰτία aitia, is not much used in modern scientific neologism. Go with what you know. Like the guy who was looking for his car keys under the street light not because that’s where he most likely dropped them but because he could see better there.
Anyway, Pöppel’s term isn’t in as wide circulation as it could be, but it’s a valuable one, because it names a thing that’s quite common in scientific fields – and other intellectual endeavours. I’ve known and seen quite a few people who have exemplified it. The parts of it may or may not have made its sense clear, but I’ll tell you what it means: ‘the love of single causes that explain everything’.