Underdetermination (sometimes
indeterminacy of data to theory) is a term used in the discussion of
theoriesThe term theory has two broad sets of meanings, one used in the empirical sciences and the other used in philosophy, mathematics, logic, and across other fields in the humanities. There is considerable difference and even dispute across academic disciplines as to the proper usages of the term...
and their relation to the evidence that is cited to support them. Arguments from underdetermination are used to support epistemic relativism by claiming that there is no good way to certify a theory based on any set of evidence. A theory (or
statementStatement may refer to:*Press statement, a statement issued to the news media*Statement that is either true or false*Sentence , a type of sentence...
or
beliefBelief is the psychological state in which an individual holds a proposition or premise to be true.- Belief, knowledge and epistemology :The terms belief and knowledge are used differently in philosophy....
) is
underdetermined if, given the available evidence, there is a rival theory which is inconsistent with the theory that is at least as consistent with the evidence. Underdetermination is an
epistemologicalEpistemology or theory of knowledge is the branch of philosophy concerned with the nature and scope of knowledge...
issue about the relation of
evidenceEvidence in its broadest sense includes everything that is used to determine or demonstrate the truth of an assertion. Giving or procuring evidence is the process of using those things that are either a) presumed to be true, or b) were themselves proven via evidence, to demonstrate an assertion's...
to
conclusionsLogical consequence is a fundamental concept in logic. It is the relation that holds between a set of sentences and a sentence when the former "entails" the latter...
.
History of underdetermination
Underdetermination receives its first modern treatment in the work of
René DescartesRené Descartes , , also known as Renatus Cartesius , was a French philosopher, mathematician, physicist, and writer who spent most of his adult life in the Dutch Republic...
. Among other skeptical
argument* In logic, an argument is a set of one or more meaningful declarative sentences known as the premises along with another meaningful declarative sentence known as the conclusion...
s, Descartes presents two arguments demonstrating underdetermination.
Descartes's dream argument points out that, while dreaming, perceived experiences (for example,
fallingFalling may refer to:*Falling , movement due to gravity*Falling *Falling *Falling *Falling , in which the goal is to hit the ground last...
) do not necessarily contain sufficient information to deduce the true situation (being in bed). Since one cannot always distinguish dreams from reality, one cannot rule out the theory that one is presently dreaming rather than having veridical experiences; thus the theory that one is having a veridical experience is underdetermined.
Descartes's demon argument is a variant of the dream argument that posits that all of one's experiences and thoughts might be manipulated by a very powerful being (an "evil demon") that always deceives. Once again, so long as the perceived reality appears internally consistent to the limits of one's limited ability to tell, the situation is indistinguishable from reality, one cannot logically determine between correct belief from being misled; this is another version of underdetermination.
David HumeDavid Hume was a Scottish philosopher, economist, historian and a key figure in the history of Western philosophy and the Scottish Enlightenment...
is the source of another important underdetermination argument, the problem of induction.
Underdetermination claimed propriety in the twentieth century with the famous work of Thomas S. Kuhn, a theoretical physicist turned philosopher. His famous work,
The Structure of Scientific RevolutionsThe Structure of Scientific Revolutions , by Thomas Kuhn, is an analysis of the history of science. Its publication was a landmark event in the sociology of knowledge, and popularized the terms paradigm and paradigm shift.-History:...
offered an alternative to linear models of scientific progress. Besides presenting a general epistemological problem, underdetermination has been used to argue against theories in the
philosophy of scienceThe philosophy of science is concerned with the assumptions, foundations, and implications of science. The field is defined by an interest in one of a set of "traditional" problems or an interest in central or foundational concerns in science...
, and especially against
scientific realismScientific realism is, at the most general level, the view that the world described by science is the real world, as it is, independent of what we might take it to be. Within philosophy of science, it is often framed as an answer to the question "what does the success of science involve?"...
.
Types of underdetermination
Underdetermination can be divided into
weak and
strong underdetermination. To claim that a theory is weakly underdetermined is to say that the currently available evidence fails to prove it, but some evidence collected in the
future might conceivably be able to. To claim that a theory is strongly underdetermined is to claim that it is fundamentally impossible to acquire evidence that could completely settle the dispute between the rival theories.
Another distinction is between
deductive and
inductive underdetermination. For two theories to be deductively underdetermined means that the available evidence does not completely contradict either theory. The case of inductively underdetermined theories is more problematic; not only are the theories compatible with the available evidence, but even attempts to determine which theory is
better fail.
The possible combinations of these two distinctions yield four types of underdetermination, though by definition a case of weak inductive underdetermination admits the possibility of its own resolution into mere deductive underdetermination through the acquisition of future evidence, otherwise it would fall under strong underdetermination. In turn, it could be argued that it is impossible for a theory to be truly strongly, inductively underdetermined: it would have to admit absolutely no possibility of valid evidence in the favor of other theories or against itself, which would necessitate it not making any novel predictions, which in turn is a valid inductive argument against it (see
Occam's razorOccam's razor , entia non sunt multiplicanda praeter necessitatem , is the principle that can be popularly stated as "when you have two competing theories that make exactly the same predictions, the simpler one is the better." The principle is attributed to 14th-century English...
).
Claims of weak underdetermination tend to center on what evidence happens to be available for some specific set of theories, while strong underdetermination often involves more general epistemological claims about what kind of evidence is possible or viable at all, either for a particular theory or for theories in general. It is widely accepted, but not universally, that all theories are weakly underdetermined; and that all theories are strongly underdetermined for most practical purposes.
Support for underdetermination
To show that a theory is underdetermined, one must show that there is a rival theory, equally well supported by the standards of evidence. A trivial example of underdetermination is the addition of an observer. For example, there is the theory that "objects near earth fall toward it when dropped". A rival theory is that "objects near earth fall when dropped but only if we check to see that they do". This rival is generated by taking any accepted theory and appending to it "whenever we look for evidence." Since one may append this to any theory, all theories are at least trivially underdetermined. If one considers such modifications of theories to be illegitimate then such "tricks" are not to be considered demonstrations of underdetermination.
More serious cases of underdetermination are illustrated when a theory admits several possibilities for which the evidence says nothing. According to
Isaac Newton'sSir Isaac Newton FRS was an English physicist, mathematician, astronomer, natural philosopher, alchemist, and theologian who is perceived and considered by a substantial number of scholars and the general public as one of the most influential men in history...
mechanics, there is an absolute space in which events are located but all that can be detected are differences between velocities. Hence, it is equally consistent with this theory to say that the solar system is at rest, as it is to say that it moves at a velocity of 37 m/s in the direction from the center of the earth to the north pole. Newton himself indicated these two possibilities are indistinguishable.
Arguments involving underdetermination
Arguments involving underdetermination attempt to show that there is no reason for belief regarding some theory because it is underdetermined by the evidence. Since the evidence does not show that the theory is the uniquely true hypothesis, there is no reason to believe it rather than some equally supported rival.
Because arguments involving underdetermination involve both a claim about what the evidence is and that such evidence underdetermines a theory, it is often useful to separate these two claims within the underdetermination argument as follows:
- All the evidence of a certain type underdetermines which of several rival theories is correct.
- Only evidence of that type is relevant to believing one of these theories.
- Therefore, there is no evidence for believing one among the rival theories.
The first premise makes the claim that a theory is underdetermined. The second says that rational decision (i.e. using available evidence) depends upon evidence that underdetermines the theory.
Underdetermination and general skeptical arguments
Some of the most powerful skeptical arguments appeal to the fact that all the evidence we could ever gather would still fail to determine which theory was true. It would remain compatible with 'skeptical hypotheses' like the maintenance of a complex illusion by Descartes' evil demon or (in a modern updating) the machines who run the
MatrixThe Matrix is a science fiction-action film written and directed by Larry and Andy Wachowski and starring Keanu Reeves, Laurence Fishburne, Carrie-Anne Moss, Joe Pantoliano, and Hugo Weaving...
. The skeptic argues that this undermines any claims to
knowledgeKnowledge is defined by the Oxford English Dictionary as expertise, and skills acquired by a person through experience or education; the theoretical or practical understanding of a subject, what is known in a particular field or in total; facts and information or awareness or familiarity gained...
, or even (by internalist definitions),
justificationJustification may refer to:*Theory of justification, a part of epistemology that attempts to understand the justification of propositions and beliefs*Justification , defense in a prosecution for a criminal offense...
.
Philosophers have found this argument very powerful.
HumeHume is a surname that originated in the South East of Scotland, of which the senior representatives are the Earls of Home...
felt it was unanswerable, but observed that it was in practice impossible to accept its conclusions. Influenced by this,
KantKANT is a computer algebra system for mathematicians interested in algebraic number theory, performing sophisticated computations in algebraic number fields, in global function fields, and in local fields. KASH is the associated command line interface...
held that while the nature of the 'noumenal' world was indeed unknowable, we could aspire to knowledge of the '
phenomenalA phenomenon is any observable occurrence. In popular usage, a phenomenon often refers to an extraordinary event. In scientific usage, a phenomenon is any event that is observable, however commonplace it might be, even if it requires the use of instrumentation to observe it...
' world. A similar response has been advocated by modern anti-realists.
It should be noted that underdetermination does not argue that underdetermined ideas are incorrect, but rather that we cannot know if they are correct. If we presuppose that conflict between different views means that none of them are correct, this is the
Middle groundArgument to moderation is a logical fallacy which asserts that a compromise between two positions is correct. The middle ground is often invoked when there are sharply contrasting views that are deeply entrenched...
fallacy.
Underdetermination and philosophy of science
In the
philosophy of scienceThe philosophy of science is concerned with the assumptions, foundations, and implications of science. The field is defined by an interest in one of a set of "traditional" problems or an interest in central or foundational concerns in science...
, underdetermination is often presented as a problem for
scientific realismScientific realism is, at the most general level, the view that the world described by science is the real world, as it is, independent of what we might take it to be. Within philosophy of science, it is often framed as an answer to the question "what does the success of science involve?"...
, which holds that we have reason to believe in unobservable entities (such as electrons) talked about by scientific theories. One such argument proceeds as follows:
- All the observational evidence for the unobservable entities of scientific theories underdetermines the claims of the theory about unobservable entities.
- Only the observational evidence is relevant to believing a scientific theory.
- Therefore, there is no evidence for believing what scientific theories say about unobservable entities.
Particular responses to this argument attack both the first and the second premise (1 and 2). It is argued against the first premise that the underdetermination must be strong and/or inductive. It is argued against that second premise that there is evidence for a theory's truth besides observations; for example, it is argued that simplicity, explanatory power or some other feature of a theory is evidence for it over its rivals.
A more general response from the scientific realist is to argue that underdetermination is no special problem for science, because, as indicated earlier in this article, all knowledge that is indirectly supported by evidence suffers from it - for example, conjectures concerning unobserved observables. It is therefore, ironically, too powerful an argument to have any significance in the philosophy of science, since it does not cast doubt uniquely on conjectured unobservables.
See also
- Poverty of the stimulus
The poverty of the stimulus argument is a variant of the epistemological problem of the indeterminacy of data to theory that claims that grammar is unlearnable given the linguistic data available to children. As such, the argument strikes against empiricist accounts of language acquisition...
- Reference class problem
In statistics, the reference class problem is the problem of defining a bayesian prior distribution by the method of imaginary reference sets. It follows from the elementary foundations of probability theory that there is no unique way of doing this....
- Scientific method
Scientific method refers to a body of techniques for investigating phenomena, acquiring new knowledge, or correcting and integrating previous knowledge. To be termed scientific, a method of inquiry must be based on gathering observable, empirical and measurable evidence subject to specific...
- Confirmation holism
Confirmation holism, also called epistemological holism is the claim that a single scientific theory cannot be tested in isolation; a test of one theory always depends on other theories and hypotheses....
- Equifinality
Equifinality is the principle that in open systems a given end state can be reached by many potential means. The term is due to Ludwig von Bertalanffy, the founder of General Systems Theory. He prefers this term, in contrast to "goal", in describing complex systems' similar or convergent behavior...
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