Underdetermination

Underdetermination arises because scientific theories often posit entities and mechanisms that are not directly observable. These unobservable elements allow for different theoretical frameworks to be constructed that, despite their differing internal structures, predict the same observable phenomena. This means that empirical success alone cannot guarantee the truth of a particular theory.

The problem of underdetermination is a central challenge to scientific realism, the view that scientific theories aim to provide a true description of the world, including its unobservable aspects. If multiple theories can equally account for the evidence, it becomes difficult to argue that any one theory is uniquely true or closer to the truth.

There are different forms of underdetermination. Transient underdetermination suggests that the evidence is currently insufficient, but future evidence might resolve the ambiguity. Permanent underdetermination, on the other hand, proposes that no amount of future evidence could ever definitively choose between the competing theories.

A classic example often cited is the curve-fitting problem. Given a finite set of data points, infinitely many curves can be drawn that pass through those points. Each curve represents a different mathematical function, and thus a different theory about the relationship between the variables represented by the data.

The problem of underdetermination has been discussed by philosophers of science for centuries, with roots tracing back to Pierre Duhem's work on the relationship between theory and experiment. Duhem argued that experiments test entire theoretical frameworks, not individual hypotheses, making it difficult to isolate the source of a potential falsification.

Quine further developed the idea of underdetermination, arguing for the "underdetermination of theory by evidence." He claimed that any theory can be made compatible with any evidence, no matter how recalcitrant, by making suitable adjustments elsewhere in our web of beliefs. This is sometimes referred to as the Duhem-Quine thesis.

The implications of underdetermination extend beyond philosophy of science, impacting fields like epistemology and metaphysics. It raises questions about the nature of justification, the limits of human knowledge, and the relationship between our theories and reality.

Despite the challenges it poses, underdetermination is not necessarily a reason to abandon scientific inquiry. It highlights the importance of considering multiple theoretical perspectives, being aware of the limitations of empirical evidence, and employing non-empirical virtues like simplicity, coherence, and explanatory power in theory selection.