ABSTRACT
Scientific advance coincided with increased freedom of thought. The knowledge provided by science has changed the world. Science is a way of establishing the truth of falsifiable statements through evidence. Unfalsifiable beliefs such of those of religion are part of metaphysics rather than science. Science is based on the logic of induction and deduction. An earlier view was that science was defined by facts (data), and any theory was an inductive generalisation from those facts. The modern view is that science is a collection of theories (conjectures or hypotheses) that are tested by data. Theories are corroborated through observation but not proven true. Theories vary in their explanatory power, some making qualitative and some quantitative predictions. The process of theory generation is as important to science as theory testing. Theory-driven research programmes tend to be more successful than data-driven research programmes. All theories are based on untested metatheoretical assumptions, and changes in these metatheoretical assumptions lead to paradigm shifts. In practice scientists sometimes make mistakes and there are issues of replicability and malpractice. Conspiracy theories arise when beliefs triumph over evidence. Democracies are effective only when truth is told.
