Skepticism

Skepticism or scepticism (Greek skeptomai: to consider, to examine) refers to any view involving doubt.

1. An attitude of doubt about whether something exists.
2. A doubt about whether something can be known for certain.
3. A doubt about whether we are correct in arguing a certain way.
4. A practical method of suspended judgment, systematic doubt or criticism.

People who have skepticism as an attitude, opinion, or method are called skeptics or sceptics.