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Logical Empiricism is a view of science that arose in the beginning of the twentieth century in Europe and which was influential, especially in England and America, for most of the century. The stimulus that gave rose to the view was the discovery and elaboration of a new Logic by Gottlob Frege in Germany and Bertrand Russell and A.N. Whitehead in England. This new Logic was the tool that the Logical Empiricists rushed to apply to scientific language to both clarify it and show how it worked.
This new Logic explained the relations between propositions and how the different relationships between propositions determined the truth or falsity of compound statements. It provided laws by which true atomic statements could be put together to arrive at true compound statements. This Logic showed how one could build up true complex statements and generalizations if one could start with true propositions. It made clear the methods by which one could preserve truth in formulating general laws from particular observation statements. Thus, it promised to bridge the gap between observations and theory by providing rules that would guarantee true laws if we started with true propositions.
The ideal Logical Empiricist model was, thus, foundationalist. If one started with a firm foundation of atomic propositions directly verified in observation, one could reach true laws by combining these atomic propositions according to the rules of logic which preserved truth. The edifice of scientific knowledge was to be built on the firm foundations of observation according to the proven blueprints provided by logic.
The way this project was conceived can be elaborated by four theses which taken together characterize the Logical Empiricist view: (following Brand Blanshard, Reason and Analysis.)
1. Logical Atomism: This is the view that the structure of the world mirrors the structure of our language or logic. Thus the scientific method based on logic would reveal to us the logical structure of the world. Logic was seen as being characterized by: (1) a set of atomic propositions which were independent of each other; and (2) logical relations or connectives which determined the truth of complex statements from the truth of the atomic statements they were built from. Thus, the world in order to mirror this structure, must consist of atomic facts with only logical or formal relations.
2. Verifiability theory of meaning: The meaning of a proposition was seen as being its method of verification in sense experience. Thus a direct link was made between the atomic statements that formed the foundation of science and the bedrock of experience. Science would be on firm ground as long as it restricted itself to atomic statements that were directly verifiable in experience. Verifiability was also, perhaps more fundamentally, a test for whether something had meaning or was merely nonsense or tautologous. All meaningful statements had to be either tautologous or directly verifiable in experience. (Sometimes falsifiability was used instead of verifiability as this criterion.)
3. Analytic-Synthetic distinction: In order for the foundational method to work, a clear distinction was needed between the fact and the logical rules that governed their combinations. Analytic propositions are ones that are true or false simply in virtue of the meanings of their terms. They don't have to be verified in experience. They correspond to ways of combining atomic propositions that are guaranteed to be true. The laws of logic are such propositions. You can test their truth by analysis of the meanings of the terms involved. The subject already contains the predicate in its meaning. Synthetic statements, however, are true or false in virtue of verification or falsification in experience. They synthesize a subject and predicate that aren't already connected by their meanings. Experience must make the connection. This clear distinction between the foundations, the facts, and the rules of logic, which govern theory building, is necessary for the system to work.
4. Emotivism: All propositions that do not meet the verification criterion of meaning, and which aren't analytic, are not cognitively meaningful at all. They are simple expressions of emotion. Art, Ethics, Religion, and metaphysics fall into this category.
The ideal method for science, according to this model, would seem to be purely deductive, starting with observations statements directly tied to experience and deducing general laws according to the laws of logic. This ideal, however seems to have two problems, both recognized by the logical empiricists:
1. This isn't the method scientists actually use. They have general laws or hypotheses ahead of time and test them in carefully designed experiments.
2. The problem of induction: There seems no way to logically deduce general statements from a number of particular statements. No matter how many white swans you see, you can't deduce, or induce, that all swans are white, because there may be some group you haven't been exposed to yet. There is no satisfactory logic of induction.
Thus, to accord more with actual scientific practice and to put aside the problem of induction, the hypothetico-deductive model of science was devised:
HYPOTHESIS. + Aux. Assumptions * PREDICTION
A Hypothesis taken together with some Auxiliary assumptions to deduce, according to the laws of logic, a prediction that can be directly verified or falsified in experience.
The Auxiliary Assumptions would include: (1) experimental assumptions: about the instruments and causes operative in the experiment. Every instrument and experiment assumes a body of theory in order to arrive at an interpretation of the data. (2) theoretical assumptions: Every hypothesis requires additional theory, usually already taken for granted as true, in order to predict a result in the experiment.
When a experimental result fails to verify the prediction, it may be these auxiliary assumptions that have to be revised instead of the hypothesis.
Scientific Progress on this view involves the accumulation of verifying results in experiments. As these grow in number we can be more confident of our hypothesis, until it finally is verified so many times it becomes a law, taken for granted as true. Science progresses by the gradual accumulation of data. An alternative version (due to Karl Popper) holds that the aim of experiments is to falsify, not verify, their predictions. If the scientists attempts to predict surprising results from her theory (if she attempts to falsify it) and fails, this provides even more powerful verification for the theory.
Scientific Explanation on this view (Carl Hempel is responsible for this view of explanation) involves the same hypothetico-deductive model. To explain an event you simply find some general covering law that would have allowed you to predict it. Sometimes this is called post-diction. One explains an event by coming up with a set of laws that would have allowed one to predict the event before-hand. By showing how the event wold have been rendered necessary by these physical laws, one explains the event.
Justification and Discovery:
On this view, there is logic of Justification, but there is no logic of Discovery. That is, Science has rules for the verification and falsification of theories, but no explanation of how scientists come up with novel hypotheses. This is thought to be due to inspiration, genius, or some other non-rational process
© 2006 David Banach
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