Common assertion: Meaningful coincidences are meaningless, non-causal, because humans are built to recognize patterns. We are pattern-recognizing animals. It is just like seeing faces in the fire: we evolved to see faces and so we see them all over the place.
Question: But what is a pattern?
Answer: A pattern is a form, an arrangement of stuff.
Bigger question: How do we recognize form?
Answer: Because we have that form within us. We are indeed pattern-recognizers, because we are form recognizers and because we have form: we are form- if we were not then we could not perceive pattern or form.
But: how could an animal evolve to recognize form from the infinite variation and boundless stimuli of the world? How could natural selection ever find the form by random search among the possibilities from matching an unbounded possible number of forms with the undifferentiated mass of nature when not perceived via form?
Conclusion: There must be a finite number of forms, and they must be preinstalled both in reality and in creatures - or else nothing could ever happen (no analysis could ever get started). This is a necessity - the only debate is over where forms come from: whether these forms just are, or whether they were created.
Reformulation of common assertion: Meaningful coincidences are meaningless - because they are not causally connected. Or, because synchronicity is not connected by identifiable sequences of causes, then it cannot be meaningful.
Comment: Hey, wait a minute! Are you saying that events are meaningless unless their causal connectivity is unknown? That a pattern is not a pattern unless we know all the causes of that pattern? Do you live by this metaphysical assumption? No - I thought not.
Further comment: And are you saying that when the causes are known then the pattern is meaningful? Because that is false: a sequence of known causes does not make a pattern, but just itself. 'A causes B causes C causes D' is not a pattern - it is just what happened. Nothing to suggest that that precise sequence of causes makes a pattern; it was just contingent history.
A conclusion: if causal sequences are the only reality - then there can be no pattern. The structure of linear sequential causality denies, makes impossible, the reality of pattern recognition
...including the reality of that pattern we call linear sequential causality.
This is a self-refuting metaphysic: necessarily invalid.
Looping back: Man is a pattern recognizing animal, reality is patterned. But (banal truism coming-up) Man is not infallible and may fail to perceive patterns and may falsely identify patterns.
The proper question is whether this specific instance of synchronicity is real. Who needs to be convinced? And what is the baseline: are all instances to be denied absent conclusive evidence of their massive improbability; or to be accepted absent evidence that they are false positives?
On what grounds do we choose between these? On whose authority?
Or maybe there is discrimination preinstalled along with the pattern precognition: not infallible of course, but good enough - if we take notice of its promptings.
But do we take notice of its promptings? Do we not, are we not trained to (actually brainwashed to), ignore the promptings of our pattern discriminating faculty?
The importance of this matter: In a nutshell, atheism.
Modern people adopt a self-refuting metaphysic (the unique validity of linear causal reasoning) which they then believe has proved itself by observation of reality. A consequence is that all instance of synchronicity are known, a priori, without discussion, to be random coincidences, a product of the human pattern making tendency.
These same people - who define in advance that all instances of pattern are illusory, then claim that there is no evidence for the reality of God (I mean, God in a generic sense); despite that thousands of years of previous humans found such evidence all about them.
And, due to their aversion from metaphysics, their extreme distractability and short attention span, they may be trapped - they trap themselves - by this incoherent logic.
e.g. Bertrand Russel: "Not enough evidence God. Not enough evidence!"
Maxim: Good philosophy probably cannot convert a soul; but bad philosophy can damn one.