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The Problem with Logical Positivism We know that scientific theories often mention unobservable things like field, force, and so on. But the logical positivists say that the only meaningful statements are ultimately about observable things. So is science largely meaningless, or is logical positivism wrong? Obviously, the logical positivists want neither to be true.
E.g., Carnap
Two strategies There are two strategies used by logical positivists to deal with this problem.
Semantic instrumentalism
Reductive empiricism
The goal of both is to say that scientific theories do not really refer to unobservable objects.
First strategy Semantic instrumentalism:
The theoretical terms of scientific theories should not be taken literally as referring to
unobservable entities, because they are merely logical constructs used as tools for systematising relations between phenomena.
Theoretical hypotheses are not assertoric.
(Assertoric means “genuinely asserts something about the world”).
Problem with first strategy However, one can object that semantic instrumentalism does not take the theoretical entities very seriously. Certainly, most scientists talk about the unobservable entities in pretty much the same way as about the observable entities.
Second strategy Reductive empiricism:
The theoretical terms can be defined in terms of observational concepts, hence statements
involving them are assertoric.
Scientific theories should not be taken literally as referring to unobservable objects.
Problem with second strategy The problem with this second strategy is that we need to
(a) give an operational definition for every property, and
(b) say that the property is nothing over and above this definition.
Operational definition An operational definition is one that concretely specifies when, in a given circumstance, one is justified in attributing the property.
E.g., one is justified to say that the temperature is 100o^ Celsius when water is observed to boil
under normal atmospheric pressure.
To give operational definitions is something that scientists often do, but what they also do is to give more than one such definitions and yet believe that they still talk about the same thing.
For instance, another operational definition of a temperature of 100o Celsius is when a properly
calibrated mercury thermometer reads 100o^ Celsius. But if, as the logical positivists must say, the property “temperature of 100o^ Celsius” is nothing over and above its operational definition, then when one looks at boiling water, and when one looks at a thermometer indicating 100o^ Celsius, these are two different properties, not just one property presents in both cases. In short, if theoretical entities are nothing but the experience we have of them, then, if we have two different experiences, there are two different entities.
The fall of logical positivism This kind of problem, plus the fact that when one communicate one’s experience there are other risk of errors, made many logical positivists change their views. Ultimately, it means that the logical positivists were not able to end the realism/antirealism debate.
Truth Another way to be an antirealist is to reject the standard account of truth as correspondence to the facts. Some important theories of truth:
- Correspondence theory of truth
- Social constructivists’ theory of truth
- Pragmatic theory of truth
- Coherence theory of truth
The correspondence theory of truth The correspondence theory of truth : a statement is true when it corresponds to the facts.
The terms in the statement refer to things and properties in the world. The conditions under
which statements are true or false (truth-conditions) are objective, and determine the truth or falsify of those statements depending on how things stand in the world. The correspondence theory of truth is the simplest and most common theory of truth.
E.g., “the snow is white” is true if only if the snow is white.
However, it is very difficult to make clear and precise what is meant by “corresponding with the facts”, and what counts as a ‘fact’ in the first place.
Social constructivist theory of truth If you are a social constructivist, you accept that a statement is true when it corresponds to the facts… …but you think that the facts are socially constructed, that is, that they are a kind of convention.
Something is a fact only on the basis of the rules and norms of our society.
This approach solves part of the problem with the correspondence theory of truth, i.e., what is a fact. But, it leads to many problems.
E.g., social constructivists and post-modernists take on science.
