(Originally written November 18, 2006 in Book 8)
What is this thing called science?
Ch. 15 - Realism and Anti-Realism
[Introduction]
Realism views science as being able to accomplish its goal of telling us about things going on beyond the surface of things (i.e. DNA) and about things that happened long ago, prior to man's existence.
Many philosophers of science doubt realism. One reason for this doubt is that claims about the unobservable world must be hypothetical to the extent that they transcend what can be firmly established by observation.
Realism is too rash for philosophy of science because it claims way more than it can reasonably defend. History has reinforced this doubt as countless theories about the unobserved world have been proven false.
Anti-realists point out that when theories based on unobservable and observable facts that when the unobservable is proved wrong and the observable is retained. They hold that the enduring part of science is the part based on observation and experiment.
Anti-realists stress the inconclusiveness of theoretical science.
[Global anti-realism: language, truth and reality]
Global anti-realism holds that we are trapped by language and cannot ever directly describe reality. We can only describe it through a human perspective.
Global anti-realism denies that we have access to reality in any way, not just in science.
While most contemporary people are global anti-realists in that we all deny that we can come face to face with reality and directly read off facts about it, that doesn't prove much. At this point, global anti-realism is a very weak thesis.
The thesis becomes stronger when it is taken to have consequences that justify a skeptical attitude toward science and knowledge in general.
Chalmers calls this strengthening of thesis "unwarranted". He admits that we understand the world through conceptional framework, but that the framework can be tested for accuracy.
We learn about the world through observing it and describing it but, also through interacting with it.
Realists use the correspondence theory of truth because it is most conducive to their position. The correspondence theory of truth states that a sentence is only true if it corresponds to reality. A sentence is true if it describes things as they really are.
One problem with the correspondence theory of truth is that it can lead to paradoxes very easily.
The Liar paradox is a good example:
Example 1: "I never tell the truth"
If this is true, then you do tell the truth.
Example 2: If one side of the card has the sentence, "the sentence on the other side of this card is true" and the other side states, "the sentence on the other side of this card is false". This situation proves that either of the sentences are both true and false, which leads to the paradox.
Alfred Tarski demonstrated how, in a reasonably simple language system, paradoxes can be avoided. He distinguished between: one must carefully distinguish sentences between 'object language' and 'meta-language'
Object language deals with truth or falsity of sentences. Meta-language talks about object language.
Using Tarski's formula one of the sentences on the card must be object language and the other must be meta-language and thus, no paradox arises.
One of the main components of Tarski's correspondence theory is that if we are going to talk about truth for sentences, we need a more general language, a meta-language.
Meta-language refers to object language and to the facts to which those object language sentence are intended to correspond.
Tarski needed to show how the correspondence notion of truth can be systematically developed for all sentences within the object language in a way that avoids paradoxes. The difficulty of his task is that for any interesting language there are an infinite number of sentences
Tarski achieved this task for languages involving a finite number of single placed predicates. He took what it means for a predicate to be satisfied by an object.
The everyday language makes it sound trivial. The predicate 'is white' is satisfied by "X" only if X is white.
Using the notion of primitive satisfaction as a given, Tarski defined truth recursively.
Tarski's work was technically important for mathematical logic. It had a fundamental bearing on model theory and effected proof theory. He showed how contradictions can arise when truth is discussed in natural language, and showed how these contradictions can be avoided.
Tarski merely showed a commonsense thing. He proved that "snow is white" is true only because snow is white.
Tarski showed that a commonsense idea of truth can be utilized in a way that is free from paradoxes that were believed to threaten it.
From Tarski's point of view, a scientific theory is true, if and only if it describes the world as it really is.
Anti-realism will maintain that Tarski has not proven a correspondence between truth and a sentence, only a correspondence between one sentence and another.
The traditional debate between realists and anti-realists, in science, concerns whether scientific theories should be seen as truth in an unrestricted sense, or if they should be seen as making claims about the observable world exclusively. Neither side of this debate defends global anti-realism.
Anti-realism
Anti-realism maintains that the content of a scientific theory involves only a set of claims that can be substantiated by observation and experiment.
Many anti-realists are called instrumentalists.
Instrumentalists hold theories are nothing more than useful instruments that aid in correlating and predicting the results of observation and experiment.
Theories, in instrumentalism, are not interpretable as true or false.
Theories must be overarching, general, simple and compatible with observation and experiment.
Bas van Fraassen is an anti-realist who is not an instrumentalist. He believes theories are true and false, but that truth or falsity is beside the point of science.
van Fraassen's merit of a theory is located in terms of its generality and simplicity and the extent to which it is borne out by observation and leads to new kinds of observation.
van Fraassen calls his position "constructive empiricism"
A motive for anti-realism is a desire to restrict science to claims that can be justified by scientific means.
Anti-Realists employee historical evidence to justify their claim that the theoretical part of science is not securely established.
Anti-realists note that even when theories are proven false there is no denying their utility in discovering new methods of observation.
"They (theories) are simply scaffolding to help erect the structure of observational and experimental knowledge, and they can be rejected once they have done their job" (Chalmers, 233).
[Some standard objections and the anti-realist response]
Anti-realists differentiate between observational knowledge, which is securely established and theoretical knowledge, which is not securely established.
One objecting to anti-realism is that if theories are not approximately true, how can they be so predictively successful in experiment?
History, however, forces the realist to admit that the predictive success is not a necessary indication of truth.
Realists claim that anti-realists can sweep difficult problems under the rug. Anti-realists would call this a caricature of anti-realism.
Realists claim that anti-realists don't take phenomena that is unobservable serious enough if they call it useful fiction. Anti-realists admit that these useful fiction and hold that as technology increases useful fictions can become observable phenomena.
[Scientific realism and conjectural realism]
Scientific realism claims that science's aim is to discover how the world behaves at all levels, not just observable ones.
Scientific realism claims that it is true because the testability of realism makes it scientific.
A key problem in the strong version of realism is the fact that history reveals science as fallible.
Ian Hacking, a realist, states that anti-realists place an inappropriately strong emphasis on what can and cannot be observed and pay insufficient attention to what can be practically manipulated in science.
Hacking maintains that an entity is real in science if it can be manipulated by science.
Some realists hold that scientific realism is too strong and attempt to weaken it.
Popper and his followers adhere to conjectural realism. Conjectural realism stresses the fallibility of our knowledge and admit that numerous theories in the past have been falsified and that we have no idea which current theories will be falsified in the future
The conjectural realist, however, still maintain that the aim of science is to discover the truth about what really exists and theories are to be judged on the extent to which they can fulfill this aim.
Conjectural realists will insist that their position is the most fruitful one in science, but will not call it a scientific position.
Conjectural realists hold that scientific realists' position as too ambitious.
Conjectural realism is a philosophical position, not a scientific one.
Conjectural realism has not criteria of judging true theories or false theories. They only recognize that in the past there have been false theories.
[Idealisation]
One objection to realism is that its theories cannot be taken as literal because it idealizes the world in a way it is not.
Theoretical descriptions are idealizations that cannot correspond to real-world situations.
Chalmers claims that the idealization of theoretical science do not pose the difficulties they are thought to.
[Unrepresentative realism or structural realism]
Science is dominated by realism because it attempts to discover reality.
Structural realism sees the theories as being more than calculating tools (anti-realism's position) but are still useful as such when they prove to be false.
