The Postprocessualist ideology has a relativistic view of and is largely based on a critique of the scientific method. In this way we can see a link to what might be considered its underling ideology, postmodernism (Preucel, 1995:148). In other words, since Postprocessualism contains no unified ideological system, it is more generally defined as a movement by how it differs from Processual archaeology.
Postprocessual archaeologists were jaded with the deterministic and functionalist views of Processual archaeology and feel that their new movement is the next step after Processualism. In this way it can be seen that the name Postprocessualism (which was first coined by Dr. Ian Hodder, its first major supporter) has a dual meaning. The first is a reference to postmodernism, its parent theory, the second being a connotation that it is the natural result of processualism (Hodder, 1986).
The general critique involved in Postprocessualism is that archaeology is not an experimental discipline, which makes it highly vulnerable to attacks that it is not objective enough. The Postprocessual archaeologists claim that, for the most part, since theories on cultural change cannot be independently verified experimentally then what is considered “true” is simply what seems the most reasonable to archaeologists as a whole. Since archaeologists are not perfectly objective then the conclusions they reach will always be influenced by personal biases (Trigger, 1989:379). As a concrete example of this we see the patriarchial underpinnings of most of archaeology until the latter half of the 20th century, where questions on the role of women in the cultures and systems under study were not asked. Postprocessual archaeologists state that personal biases inevitably affect the very questions archaeologists ask and direct them to the conclusions they are predisposed to believe.
Whilst this may sound as a vague theoretical idea, it has definite consequences in the actual practice of archaeological fieldwork. In order to collect data and analyse it, the archaeologist must first decide which questions they want to ask. Given that typical digs will cause hundreds of thousands or perhaps millions of artefacts to be recovered and analysed, and the cost and effort of reanalysing artefacts is prohibitive, the question on categorization and analysis techniques must effectively be posed prior to an excavation or survey starting. These techniques will often reveal biases.
Some postprocessualists believe that this means we can never accurately reconstruct the past, so why try? They advocate the use of archaeological data to produce historical fantasies. "Why not?", they say. "It's just as likely as any other explanation archaeologists can offer." Some also argue it is perfectly allowable to use archaeological data to support personal political and social agendas (Trigger, 1989:380). They perhaps overlook the problem that archaeology has a checkered past at best when used to support political agendas. Some of these causes include Nazism, colonialism, imperialism and racism (Trigger 1984:615).
Postproccessualism is not popular in America, where Processualism was born and continues to be the main focus of archaeology. To a large extent Processualists believe in the scientific method - that archaeology is credible to the extent to which it employs the scientific method, and find the much less scientific nature of Postprocessualism to be a step in the wrong direction. Postprocessualism has gained popularity in Europe, though Processualism is strong there as well. Some archaeologists speculate that the rise of postprocessualism in Europe may be a direct result of anti-American sentiment, though this is subject to debate (certainly, it would be by the Postprocessualists)
However, with all these differences it is possible to find some common ground between processualists and postprocessualists, even if they sometimes do not want to see it. Both Processual and Postprocessual archaeology want to know about the people of the past. Both are concerned about how we know about people in the past and whether that knowledge represents the actual past or just a personal mental reconstruction of the past. While some postprocessualists argue that any understanding of the past is impossible most believe that, if nothing else, we should still try to do archaeology as best we can while struggling to keep concerns about our own bias constantly in mind. Both wish to eliminate this bias and come to an objective understanding of the reality of the past, however they differ very significantly in how to best achieve this end.