Skepticism (British spelling: 'Scepticism\') can mean:
- Philosophical skepticism - a philosophical position in which people choose to critically examine whether the knowledge and perceptions that they have are actually true, and whether or not one can ever be said to have true knowledge; or
- Scientific skepticism - a scientific, or practical, position in which one does not accept the veracity of claims until solid evidence is produced in accordance with the scientific method.
The term skeptic is now usually used to mean a person who is taking a critical position in a given situation, usually by employing the principles of critical thinking and the scientific method (that is, scientific skepticism) to evaluate the validity of claims and practices. Empirical evidence is important to skeptics as it is possibly the best way to determine the validity of a claim.
While such skeptics are usually atheists, some are deists or even theists. While skepticism involves the use of scientific method and critical thinking, this does not mean the skeptic is using them consistently or simply finds that there is indeed evidence of their belief.
Skeptics are often confused with, or even denounced as, cynics. However, valid skeptical criticism (as opposed to arbitrary or subjective misgivings for an idea) strictly originates from an objective and methodological examination that is often agreed between skeptics themselves. It should also be noted that cynicism is generally defined as a position that maintains an unnecessarily negative attitude toward human motives and sincerity. While the two positions are not mutually exclusive and many skeptics may also be cynics, they each represent a fundamentally different statement about the nature of the world.