Generally, theories make use of ‘facts’ (that is, assumptions which are generally accepted to be true), and ‘hypotheses’ (that is, speculations about how things are). Facts and hypotheses are combined to make an argument. This produces a conclusion which ideally can then be tested against experience. There are at least six tests as to whether or not a theory is a good one: •  Does it achieve its aim of explaining things beyond its assumed material? •  Is the theory as simple as possible? •  Are the underlying ‘facts’, the stated and the unstated ones, really    established? •  Are the hypotheses reasonable and eventually capable of being tested? •  Is the argument that links the facts and hypotheses a logical one? •  Are the predictions generated by the theory capable of being tested? BACK