Underdetermination - Underdetermination and Evidence

Underdetermination and Evidence

To show that a conclusion is underdetermined, one must show that there is a rival conclusion that is equally well supported by the standards of evidence. A trivial example of underdetermination is the addition of the statement "whenever we look for evidence" (or more generally, any statement which cannot be falsified). For example, the conclusion "objects near earth fall toward it when dropped" might be opposed by "objects near earth fall toward it when dropped but only when we check to see that they do." Since one may append this to any conclusion, all conclusions are at least trivially underdetermined. If one considers such statements to be illegitimate, e.g. by applying Occam's Razor, then such "tricks" are not considered demonstrations of underdetermination.

This concept also applies to scientific theories: for example, it is similarly trivial to find situations that a theory does not address. For example, classical mechanics did not distinguish between non-accelerating reference frames. As a result, any conclusion about such a reference frame was underdetermined; it was equally consistent with the theory to say that the solar system is at rest, as it is to say that it moves at any constant velocity in any particular direction. Newton himself stated that these possibilities were indistinguishable. More generally, evidence may not always be sufficient to distinguish between competing theories (or to determine a different theory that will unify both), as is currently the case with general relativity and quantum mechanics.