Postmodernists, whatever their field, tend to be skeptical of the certainty of knowledge. Postmodernism has been influential in a number of fields, including history, where it has called into question the validity of reconstructing a narrative from texts, and the degree to history is a fictitious construction of the modern mind. Postmodern thinkers have also called into question many ideas that have previously been regarded as unchanging and certain, particularly gender and race, and questioned some of the master narratives of history and literature. Some postmodernists tend to be deconstructionists, questioning the relationship between words and the things they are meant to signify. This calls into question the degree of accuracy or objective truthfulness that can be included in any text. There are many different aspects to postmodernism, but generally speaking, they all come back to the crucial theme of uncertainty of knowledge.