Hmm, I'm not convinced, Gerry, but I'm struggling to express my reasons why. OK, consider:
cynic - one who is critical of the motives of others; who believes all people are motivated by selfishness; whose outlook is scornfully and often habitually negative.
optimist - one who is disposed to take a favourable view of things; who usually expects a favorable outcome.
As cynicism is geared towards people's motives, and optimism is geared more generally towards the outcome, I'm not sure they can be linked in this way. Cynicism isn't just seeing a bleak outcome, like pesimism, it's more of a warped/skewed judgement of someone's reasons for an action that results in a bleak outcome. If that makes sense!
In your examples, to me, the first could be cynical or pesimistic and the second, arguably, optimistic or pesimistic - only at a stretch, cynical. Both depend on whether a value judgement is being made on the motivation of the people concerned. There almost needs to be more information in each case to decide.
What about how types of people would interpret your second phrase, to expand:
fumei said:
it will probably fail...but who knows? Maybe not.
Optimist - will be drawn to the words "... Maybe not" and will think the best of the person saying the phrase and its object (the marriage).
Pesimist - will be drawn to the words "... will ... fail" and no doubt believe that is the case, no matter what anyone else says.
Cynic - believes that the person saying the phrase, and the couple getting married, are inherrantly self-serving and unscrupulous and will form a suitably scornful, acidic view of all parties and the prospect of the marriage.
So, I think it may be possible to be cynical in regard to people's motivation, but still generally positive about outcomes and therefore a 'cynical optimist', but you cannot be both cynical and optimistic about the same thing.
Tony
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Reckless words pierce like a sword,
but the tongue of the wise brings healing (Solomon)