In Predetermined, Hibbings et al. described characteristics of liberals versus conservatives based on psychological and biological testing. Conservatives tend to prefer black and white answers, while liberals are more nuanced. Conservatives do not tolerate uncertainty well, while liberals do. Conservatives believe in self-reliance and responsibility, with a certain lack of tolerance. (Note that both political parties exhibit a fair degree of intolerance.) They tend to focus on the negative and concerned with public safety. Liberals rely more on social norms (which are changing) and the role of society (often government) to settle issues and provide a social safety-net. In terms of government and economics, conservatives favor free markets, individual liberty, and traditional values. Government should provide defense, rule of law and maximum freedom. Liberals believe in strong government, emphasis on equal rights and opportunity. Government should reduce social ills and protect human rights.
Many of these differences are ancient. Plato was considered liberal, Protagoras (a sophist) conservative. Aristotle suggested a Golden Mean (while the Buddha had a Middle Way). British economist/philosopher John Stuart Mill (a utilitarian) described one party of order and stability versus a party of progress and reform. Thus, arguments can be traced through philosophy and history that break down as conservative/liberal.
Presumably, most people agree on many things: government rules and regulations should be efficient and effective, based on some reasonable objectives; there should not be more government rules than absolutely necessary; revenues (mainly taxes) should match spending needs, annually or over time (the concept of inter-generational equity). [Economists and others suggest the need for debt and therefore some level of deficit spending, usually stated as a percent of gross domestic product]. I hope a majority prefers solutions to problems such as unsustainable spending. For example, the only way to fix Social Security I'm aware of is raise revenue and cut benefits. Tax cuts (generating huge deficits) during a booming economy is a recipe for long-term fiscal disaster. What is the remedy when recession comes?
Hibbings and others use multiple techniques in their research. Questionnaires such as the Wilson-Patterson Index as Conservatism are used. Biology is measured with gaze cuing, brain imaging, genetic testing and so on. Generally, the biological tests track the survey results. I'm interesting in the people in the middle, a topic not addressed in this book. Specifically, differences between male and female, age, geographic region, demographic and economic characteristics, and so on.