For example, one strongly held strong belief that I have is that the speed of light is the maximum speed of matter. So when CERN publishes a report that they discovered superluminal particles, I don't instantly switch beliefs - that would be weakly held. Instead I stand my ground and wait to see if it's reproducible, etc.
Further many people disagreed with QM even with a lot of evedence backing it because it was so different from what they where used to. They essentially had not threshold to update their beliefs.
Yes I would have updated my beliefs, but my new beliefs would be both weak and weakly held. If in 20 years the consensus was still solid they would become both strong and strongly held.
> Because that's not even close to enough evidence for say global worming opponents.
For them the evidence they need to see is perceptibly rising temperatures or sea levels. A lot of people view climate change as highly politicized/hyped science (which it is) and are therefore skeptical if not of climate science of the apocalyptic predictions (which are not universally agreed upon by climate scientists). They will change their minds if they see that it hasn't snowed in 10 years or if their beach front properties are getting swallowed by the ocean.
Changes that are obvious and massive to the CEO of a company which owns ski resorts around the world may seem meaningless to people living at those same locations. I like most people don't recall the date of each snowfall over the last 50 years, because it has little real impact on me, but keeping accurate track of those same storms can be of vital importance for some people who see these trends as both obvious and critical.
Now some things like gravity are very strong beliefs. But, you should be open to the possibility that something else is going on even with gravity. That does not mean you should stop believing in gravity based on a slick YouTube video, but rather accept that with solid evedince something else might be going on.