Sample from chapter 9 of Becoming a Critical Thinker
7. Evaluating theories
Obviously, it is very important to be aware of the kind of theory one is confronted with--scientific or non-scientific--before one sets out to try to defend or refute the theory. If the theory is non-scientific, it would generally be useless to try to defend or refute it by empirical data. If a non-scientific theory is not self-contradictory and is consistent with the evidence of experience, it cannot be shown to be false. Of course, unlike scientific theories, non-scientific theories cannot be empirically confirmed either.This does not mean that non-scientific theories can't be checked against observation and experience. Any theory, to be reasonable, must be consistent with what is observed and experienced. But since empirical predictions are not meaningful tests of non-empirical theories, the fact that a non-scientific theory is consistent with experience is hardly a confirmation of the theory. But, since a self-consistent non-scientific theory cannot be refuted, it cannot be empirically tested; metaphysical theories cannot be empirically confirmed to any degree, as scientific theories can.
Are scientific theories therefore superior to non-scientific theories? Or, to put it another way, is science superior to religion, art, ethics, metaphysics, etc.? Such a question is absurd. Asking whether science is superior to religion or philosophy is like asking is `intelligence is superior to love?' or `is justice superior to good health?' Not all questions or values which human beings find worth pursuing and committing themselves to can be approached scientifically. There can be no doubt that scientific theories fulfil a vital human need. But so do non-scientific theories, whether they be in the field of cosmology or religion, art, morality, knowledge or even science.
Good scientific theories share in common with good non-scientific theories the quality of being free from self-contradictions, consistent with experience, and free of ad hoc hypotheses to patch up holes or weaknesses. Also, all scientific and some non-scientific theories attempt to make sense out of the phenomena they are put forth to explain. Some metaphysical theories attempt to make sense out of all things which exist. Other non-scientific theories are less ambitious and attempt to make sense out of a single area of human experience, e.g., aesthetic or moral experience.
A good theory, regardless of whether it is scientific or not, must be sensible. But just how sensible a theory is depends upon the field in which it is offered and upon current knowledge, beliefs and values of those studying the subject. Generally, the best scientific theories are very rich: they explain and unify a great deal of experience and provide a picture of things as a whole. Generally, the best non-scientific theories provide a sense of value and significant meaning to the phenomena they explain or prescribe for.
To some extent, all theories are personal. Yet, that does not mean that all theories are epistemologically equal. Some theories are richer, more sensible, more useful, more elegant, more powerful and more reasonable than others. It would be presumptuous, and probably not very useful, to try to establish a complete set of a priori conditions which a theory must meet before any reasonable person should accept it. It may well be that theorizing, whether scientific, philosophical or pseudoscientific, issues from the same human motive to unify and give order to experience, to make sense out of the many different aspects of existence, and to find significance and richness in human experience.
If so, that is all the more reason to insist upon more, not less, critical thinking in all our theorizing endeavors, whether scientific or not.