Scepticism, as a general attitude with which to approach the world, is often understood to oppose the various forms of dogmatism adopted by fanatics and fundamentalists. Whereas the history and tradition of the philosophical movement underpinning contemporary Scepticism is steeped in logical arguments and nuanced with certain degrees of variety, a uniting thread current throughout its history could (when simplified) be seen as the rejection of any claims to absolute truth or unassailable knowledge. Instead, a sceptic will only admit to the subjective appearance of a truth or of knowledge without believing that the subjective appearance of something is enough to warrant the negation of epistemological doubt.
A sceptic, therefore, is in a state of doubt with regards to claims of knowledge: s/he questions at a fundamental level whether or not they know anything, and whether or not any real, absolute knowledge is even possible. This doubt is primarily based on the premise that subjectivity yields different interpretations of the world, and that if all experience of the world is modulated by subjectivity, then any truly objective knowledge is improbable, if not actually impossible.
This might seem like an extreme position given the huge advances made by the natural sciences, especially since the Industrial Revolution: the sceptical argument that would be employed in its defence against this charge is simply that whereas science allows us to manipulate the material world, its continual revolution indicates that progress and utility are not substitutes for a transcendent, objectively indubitable knowledge.
Indeed, many scientists themselves would rush to point this out to any fundamentalist who adhered, with a religious intensity, to the belief that science presents us only with truth. Science, however, is not as much a victim of dogmatic thought as religion, nationalism, racial relations, politics, etc., has been. One could perhaps think of a sceptic as someone who resists the temptation to take things at face value: by analogy, a sceptic will not buy property based on a real estate agent’s assertion that it is a good investment.
The common denominator amongst the latter group is that these fields of experience are highly biased by subjectivity and self-interest, if not by peer pressure and cultural heritage. Whereas science can claim to rely methodically on observable data that goes to either prove or disprove the possible validity of a theory, politics and religion often rely, for their veracity, on unobservable beliefs and facts not in evidence.
It is primarily against ultimate truth claims that cannot produce observable empirical evidence for their claims (such as those that are often offered by religious institutions and political ideologies) that scepticism aims its “barbs”. It is important to point out, however, that strenuous disagreement remains at the level of intellectual engagement and not that of intimidation, physical or otherwise. Any type of intimidation pertaining to a particular worldview would naturally counter Scepticism’s spirit of employing a critical and logically rigorous method in evaluating culturally embedded and habitually entrenched truth beliefs.
Scepticism, ultimately, aims to encourage critical thought on all levels of experience, from the personal and exceedingly subjective, to communal belief and even large scale societal perception. It is probable that the more critical reasoning is employed, the greater interpersonal and intercultural understanding (and therefore harmony) there will be.