Answer:
There is no formal scientific evidence indicationg the existence of clairvoyance. Clairvoyents, even the well meaning ones, have all proven to be frauds.
Another Point of View
Some people really do have glimpses into the future "Clairvoyance"
It is not a 100% event, sometimes only a person is seen or a "feeling" of danger comes over them. At other times the "message" is very clear, but the Clairvoyant has no way of contacting the people involved. Those who get these sorts of things often keep journals of what they "see" and clippings of news events that confirm their "sight." A 75 to 90 percent rate of accuracy is not unheard of, but certainly uncommon.
As Clairvoyance is not something that lends itself to scientific proof many people do not believe in the ability.