Characteristics of good theories

Friday August 25, 2017

In Objectivity, Value Judgment, and Theory Choice, Kuhn gives a partial list of characteristics that good theories share:

1. Accurate: within its domain, consequences deducible from a theory should be in demonstrated agreement with the results of existing experiments and observations
2. Consistent: internally (with itself) and with other currently accepted theories applicable to related aspects of nature
3. Broad scope: consequences should extend far beyond the particular observations, laws, or subtheories it was originally designed to explain
4. Simple: bringing order to phenomena that in its absence would be individually isolated and, as a set, confused
5. Fruitful: leading to new research findings; disclosing new phenomena or previously unnoted relationships among those already known

In The Beginning of Infinity, David Deutsch objects to positivism or anti-realism, but has not so different criteria to Kuhn. Deutsch focuses on these two:

1. Hard to vary: having no extraneous or non-explanatory characteristics; possibly related to Kuhn's "consistent" and "simple"
2. Reach: similar to Kuhn's "broad scope," "fruitful," and possibly even "simple"

Deutsch mostly takes "accurate" as a given or obvious requirement. Even this seemingly simple goal becomes complicated when people disagree about "the results of existing experiments and observations."

The focus of both authors is on scientific theories, as in (for example) physics. When explaining human affairs, the same criteria may not always be perfect guides. For example, many non-simple conspiracy theories are not true, but there can really be conspiracies, and things may not be obvious.