“In this house, we believe in…science.”
“The science is settled.”
As I began demonstrating in a previous essay, anyone who espouses such clichés is scientifically illiterate. Science is not some ahistorical abstraction embodying the proverbial God’s eye view of the cosmos. It has a particularly colorful past extending back centuries, a history replete with all of the nit and grit, all of the contingencies and relativities, characteristic of all cultural phenomena. And the history of science includes, of course, rival philosophies of science.
It was also mentioned that the 18th century philosopher Immanuel Kant revolutionized Western philosophy when he argued that it is not, as had always been assumed, the mind that passively and impartially mirrors the world. Rather, it is the world that is made to comport with the mind. The only world that human beings can meaningfully speak of is the world that has been constructed in terms of the mind’s own internal structures. These structures are comprised of the “pure intuitions” of space and time and a dozen “categories,” including the categories of “causality” and what philosophers have traditionally called “substance.”
Space, time, universal causation, and the existence of entities that endure over time are not necessarily objective features of the universe to be discovered by scientific inquiry but, quite the contrary, the very pre-conditions of all inquiry. They are features of the human mind supplied in advance of all experience and in the absence of which we can experience nothing.
Kant was provoked to develop his “Copernican revolution” after he was awakened by his “dogmatic slumbers” by his predecessor, David Hume. To Kant’s legacy we will return. Not everyone, it is critical to note here, was persuaded by him to abandon Hume.
Hume contended that there were two and only two types of knowledge propositions: propositions expressing “relations of ideas” and those expressing “matters of fact.” The former are “analytic” or “tautological”: They are true by definition. The latter are “synthetic” in that their truth can be confirmed or disconfirmed only through observation.
“All bachelors are unmarried men,” “Green things are colored things,” and “Squares are four-sided figures” are all illustrations of statements expressing relations of ideas. They are universally and necessarily true, i.e. they cannot be false. Their truth is a priori, known prior to experience.
“Jack is writing a paragraph on the philosophy of David Hume,” “The car is red,” and “The Earth revolves around the sun” are all examples of statements embodying “matters of fact.” This means that, if true, they are not necessarily true but, rather, contingently true: They happen to be true, but they could’ve been otherwise. To know that they are true or not, we have to see for ourselves, so to speak.
Statements expressing relations of ideas pertain only to concepts. They don’t necessarily tell us anything about the real world. Thus, “Green Martians are colored beings” is necessarily true. As far as we can determine, there are no Martians, let alone green Martians. Yet this is irrelevant, for all that matters here is the relation between the ideas or concepts of green and colored. Statements expressing matters of fact, on the other hand, purport to inform us of the actual features of the world.
This distinction that Hume drew between these types of knowledge claims would eventually become known as “Hume’s fork.” Regarding a work that contained claims that were neither true by definition nor empirically verifiable, Hume’s verdict was clear and decisive: “Commit it then to the flames, for it can contain nothing but sophistry and illusion.”
In the 20th century, a group of philosophers known as the “logical positivists” or “logical empiricists” heeded Hume’s command. Only those statements that were true by definition and those that could be verified or confirmed through observation were deemed meaningful. In stark contrast, religious, metaphysical, aesthetic, and even ethical claims, though not always (but sometimes) dismissed as being meaningless, were regarded as being nothing more than subjective and figurative expressions of preference or emotion.
The logical positivists, despite the disagreements that occurred among them, were unanimous in endorsing some version or other of the principle of “verifiability,” i.e. the principle that cognitively meaningful statements that were not analytic in nature must be capable of being verified via experience.
And it is this conviction of theirs that led to another: The belief in “the unity of science.”
The Vienna Circle comprised a diverse array of philosopher-scientists and scientist-philosophers who were committed to establishing the unity of all of the sciences. The German philosopher Moritz Schlick, who was also a physicist, is credited with spearheading the group in 1924. From that time until 1936, members included fellow physicist Phillip Frank and such mathematicians as Hans Hahn, Olga Hahn-Neurath, Theodor Radacovic, and Gustav Bergmann. Otto Neurath, a social scientist and the husband of Olga Hahn-Neurath was a member, as was, notably, the philosopher and logician, Rudolph Carnap. The Vienna Circle would persist beyond the 1930s, with new members and associates coming and going.
Such thinkers as Gottlob Frege, Bertrand Russell, and Alfred North Whitehead labored diligently to show that mathematical propositions were ultimately nothing more and nothing less than logical propositions which, being true by definition, told us only about the meanings of linguistic terms and nothing at all about the nature of the world. The impetus for this programmatic “logicism” was unmistakably positivist: If mathematical propositions are simply statements of logic, then it is to experience alone that we must turn if we wish to acquire knowledge of the universe.
Pythagoras and Plato are representative of a Western philosophical tradition encompassing centuries and millennia that largely maintained that numbers are real. However, positivists like Russell could have none of this, for if numbers were something other than the words (numerals) that figure in language, this would mean that immaterial entities are real. Yet immaterial entities like numbers, God, objective moral truths, and so forth, being unobservable, undercut the radical empiricism to which the logical positivists were committed.
Other 20th century thinkers would show in time that Russell and his ilk endeavored to fulfill an impossible task as numbers, being infinite, could never be reduced to the finite set of the axioms and principles of logic. And, by the late 1960s, logical positivism, as well as the unity of science movement, would be all but dead—or, in the words of the Australian philosopher John Passmore, “as dead as a philosophical movement ever becomes.”
In the next installment of this series, we will see the specific challenges that were made to the positivist conception of science, beginning with who is perhaps that most prominent of all 20thcentury philosophers of science, Karl Popper.