A cynic wants to put down any idea that is not theirs or they don’t already believe in.
A skeptic wants to find a solution but will require reasoned support that solution, even if it's theirs. That's a key differentiator: If you don’t hold your own ideas to the same standard of proof that you hold other people’s ideas, then you are a cynic.
Cynic: “That will never work because I don’t think it will work.”
Skeptic: “I think X and Y could cause a problem. Do you agree or disagree? Why?”
Fact-based decision makers have to be skeptics, but it is too easy to become a cynic, and that will destroy a healthy, fact-based problem-solving culture.