Can we use markets to answer how likely the "may" in "Stem cell research may provide us with cures for diseases" is?
According to the PPX market the stem cells are 94.50% likely to cure a disease by 2015. So roughly if you bet 19 dollars that stem cells will cure a disease by then you would only get 20 back.
This means stem cells are viewed as highly likely to cure human diseases in the near future. This information is useful as stem cells which come from human embryos are highly controversial. When defending any such controversial action is is useful to be able to estimate its eventual usefulness.