In the wake of the recent debate between Bill Nye and Ken Ham on creation, I have decided to write a series of articles articulating some of the most important debates concerning the relation of scientific investigation to worldviews that have taken place throughout the 20th century. One of the reasons I am doing this is because presuppositionalists are oftentimes accused of raising their objections to secular science as a desperate parlor trick to justify an otherwise unjustifiable belief in Christianity, when in fact, the issues that many presuppositionalists raise are perennial discussions in the philosophy of science that have troubled scientists of all religious persuasions, including those who completely reject the validity of religious belief. Indeed, many of the objections presuppositionalists raise are precisely those that have been raised and discussed by unbelieving philosophers of science and scientists. Various solutions have been offered at this time. Some of these questions, which I intend to discuss, include:
-What impact, if any, do our presuppositions about reality have on our scientific investigation?
-When faced with conflicting interpretations of the same data among scientists, how can we decide between interpretations? According to what standard are we able to make this determination?
-In light of the fact that scientific consensus is in continual, radical flux, can scientific investigation really produce any knowledge at all?
-Is the association of scientific investigation with atheism or agnosticism historically normative, or is it a relatively recent development?
-Is authentically scientific investigation compatible with Christianity?
-Can we ground scientific investigation in anything substantive and foundational, or is it necessarily a series of totally arbitrary methods and practices which cannot be demonstrated to be any more conducive to truth than any other set of methods and practices?
-How can scientific investigation reliably determine that it is such and such a variable that produces such and such an effect and not another? How can we avoid confounding variables? How can we demonstrate that the correlation is not an incidental one, but is a legitimate example of direct or immediate causation?
-What "is" science, anyway? In what way or ways, if any, does it differ from ordinary, commonsense induction and abduction? How ought scientific investigation proceed, according to what standard, if at all, can authentically scientific investigation be distinguished from pseudo-science, junk science, etc.?
-Is pragmatic and predictive success in scientific investigation really commensurate with knowledge acquisition? Is scientific 'discovery' really correlated with scientific 'justification'?
I intend to discuss the different main figures in 20th century philosophy of science, the questions they grappled with and the answers they attempted to provide. Finally, I will discuss how different Christian presuppositionalists have responded to such debates, and make a case for how I believe presuppositionalists ought to respond.
In the public square, scientific investigation tends to be associated with a specific set of metaphysical commitments that are not innate to it, and in fact historically have not necessarily been associated with the practice of scientific investigation at all. I refer in particularly to metaphysical materialism, according to which all of reality can be reduced to nothing but the behavior of matter, as well as atheism or religious agnosticism. I would like in this article to trace the genealogy of this tendency throughout the 19th and early 20th century, and demonstrate how the vast majority of later 20th century philosophers of science came to reject the attitude of unmitigated optimism towards science, according to which scientific investigation is regarded as the only legitimate form of knowledge acquisition.
What has come to be regarded as the attitude of "modern science" was arguably born in the 19th century, in the person of Hermann Lotze.
"Rudolph Hermann Lotze (1817–1881) mediated the transition from the exuberance of German idealism, in the first half of the nineteenth century, to the sober, scholarly and scientific ethos that came to prevail in the second half. He adapted the notion of “chief” or defining problems in the philosophical sub-disciplines, inherited from Herbart, and brought opposing approaches to bear on them, in a quasi-systematic way, preparing the way for the modern textbook. A professor in a changing situation, moving toward bureaucratic centralization in an encompassing national state, he mostly restricted his attention to academic issues, appealing to his peers (but not the public) in the now rising professional journal (while maintaining a lively interest in things quotidian)"(Sullivan, 2010).
We see in the person of Hermann Lotze the rejection of the philosopher as a kind of Renaissance man, who speculates on a wide variety of topics and attempts to integrate them in a systematic manner in order to put forth a holistic worldview. Instead, we see the beginnig of distinct subject matters (biology, anthropology, sociology, philosophy, etc.) occupied by specialists in that field, whose work is undertaken according to a systematic manner that is peculiar to that very field.
"In his reviews, criticisms, and polemical writings he is as dignified as Kant and Herbart had been; he is never impolite as Fichte and Schelling frequently were; nor does he fasten upon his opponents any stigma as Hegel frequently succeeded in doing; he is quite above that virulent and unmannerly invective by which Schopenhauer tries to crush, but never actually damages, the arguments of thinkers whom he chooses to regard as enemies. But the style of Lotze reflects one characteristic trait of modern thought. The confidence and self-assurance of Kant, Fichte, Hegel. Schopenhauer, and of the earlier Schelling have disappeared." (Merz, 1907–14, p. 493)(Sullivan, 2010)
In the absence of the cult of the romantic philosopher-genius, arorse the cult of the professional journal:
"The new model of the academic researcher demands the replacement of prominent personalities—i.e., romantic ‘geniuses’—by the new exemplar of the sober scientist. Significant, as well, are the new material constraints on the practice of philosophy: not just the rise of the university professor—after Kant—as the most prominent representative figure, but the correlative emergence of the professional journal as the typical venue of presentation and publication. Of course, the atmosphere of political repression, following the failed revolutions of 1815 and 1848, surely played a crucial role in limiting the wider ambitions of philosophers and reinforcing the need for a more neutral tenor. Indeed, the same political pressures and bureaucratic demands associated with the state professor's status as “civil servant” began to figure prominently during the first half of the nineteenth century, harkening back to the Fichte's difficulties in the Atheismusstreit (1798/99) and leading up to, among other things, the dismissal of the “Göttingen Seven” (1837)—just to enumerate a few salient events from the German situation alone.
The efficient causes of this portentous change were not limited to the social-political sphere: in the numerous departments that came to make up the philosophical, or lower, faculty of the university, other important developments were also afoot. First, and foremost, there must be numbered the emergence of new, separate disciplines—such as geology, chemistry, biology and psychology—and the resulting squabbles over relative positions, proper boundaries, and the subsequent agon of “role purification” (see Kusch, 1995). In addition, the rapid advances in the scientific discovery had multiplied the previously manageable amounts of data and, hence, suggested to some that the task of philosophy was now to restrict itself to explaining “how the problems of speculation still connect themselves with the ever increasing mass of special knowledge that the labours of the new generation have accumulated” (Adamson, 1885b, p. 573). In this context, the cognate conceptions of philosophy as a synthesizing or supervisory endeavor began to gather adherents. Indeed, the “rehabilitation of philosophy” [Rehabilitierung der Philosophie] (see Schnädelbach, 1984, pp. 103ff) is perhaps the central foundational issue of the day and names “the attempt to allot to philosophy, in a scientific age, a domain of problems that would be independent of the special sciences” (ibid., p. 103). Here, as elsewhere, Lotze emulates Fichte: while science can surely explain what is, it can never elucidate the ultimate value or meaning of the phenomena it reveals—that alone is the task of philosophy (cf. ibid., p. 178)"(Sullivan, 2010).
It is difficult to overstate the importance and influence of Hermann Lotze. Although rarely discussed by name today, he exercised an important influence on many of the thinkers whom we will discuss:
"Oddly—despite his one-time preëminence[keeping in mind that in his day he was regarded as one of the world's philosophical greats]—Lotze founded no enduring school. However, his teaching directly influenced such prominent students as Windelband and Frege and his ideas were still being considered and debated as late as the 1920s by a numerous notables, including Heidegger and Carnap. Even in his own day, Lotze's reputation soon spread beyond the continent. As a result, he became a substantial force in the English-speaking world affecting, among others, Green, Bradley, and Bosanquet, in Britain, and Royce, James, and Santayana, in America. Indeed, it is principally by this latter means that he came to hold some sway with both the early Moore and the early Russell. Furthermore, because his influence extended through both Anglo-America and the Continent, some have postulated his unconscious but seminal presence in the emergence of analytic philosophy (cf. Sluga, 1980, Gabriel, 2002, Milkov, 2000); and, likewise, studies of Lotze by historians of phenomenology (Rollinger, 2001, Hauser, 2003) have also begun to emerge"(Sullivan, 2010)
Although he exerted a decidedly secularizing influence on the intellectual disciplines of the 20th century, he was difficult theologically to pin down with any precision:
"Finally, in this same moment, when philosophy was only beginning its (eventual and complete) confinement to the academy—and becoming simultaneously more specialized and less provincial—Lotze was (notably) the darling of numerous Protestant theologians and preachers: both conservatives who sought to popularize him as a fanatical opponent of mid-century materialism, and others, of a more liberal character, who fastened on to his “personalism” as the proper antidote to the dangerous heterodoxies of pantheism, rationalism, agnosticism and atheism (cf. Hall, 1912, pp. 94n-96n). While Lotze himself may not have endorsed these distortions, there was, nonetheless, something about his work that permitted such misuse. Santayana, a keen observer of this very phenomena, insisted on inserting an important cautionary note: he remarked dryly that one ought not to be misled by Lotze's continuous reference to “souls” or “God” as “a certain acceptance which Lotze has found in conservative circles is perhaps due to insufficient considerations of his meaning”:
Lotze is inclined to give old names to new things; he is fond of a metaphysical nomenclature, and his terms are generally more mysterious and old-fashioned than his ideas. Thus he speaks of the soul, of substance, of free will, of efficient causation, of a personal God; but these phrases stand in his system for comparatively modest and legitimate conceptions. The words may please us in themselves; but we shall be disappointed if we welcome the things for love of the names they bear. (Santayana, 1971, p. 153)
If correct, this suggests that Lotze, once again, followed the lead of Fichte in using traditional language to mask more deeply naturalistic conceptions than the surface meaning of the ordinary wording might initially suggest. (This peculiar feature of the expression of his thought must be made continually present by the active reader.) In any event, Lotze's continuing influence in the twentieth century (ironically) came mostly through the theological curriculum of classical liberal Protestantism, still in evidence until the late-1960s (cf. Reardon, 1968)""(Sullivan 2010).
Our own interest is limited to the historical context in which Lotze was writing as well as its effects on later intellectuals. Lotze's work contributed to the discrediting of Hegelian idealism and its various offshoots as legitimate, serious philosophical thought, and also contributed to the sort of highly compartmentalized, reductionistic tendency of thought we know today as "scientism":
"After modernism, philosophy changed. But the change was slow in coming and, well before the full impact of high modernism, Hermann Lotze reigned as the single most influential philosopher in Germany, perhaps even the world. Although almost completely unread today, his substantial body of work exemplifies the new academic philosophy (“Kathederphilosophie”) that flourished between the demise of the post-Kantian idealisms and the rise of scientific philosophy proper; he is usually credited with assisting “the rejection of Hegel and Absolute Idealism within the bounds of academic philosophy” (Schnädelbach, 1984, p. 169). Although the time period under discussion is sometimes denominated by the phrase “between idealism and positivism,” it might be more accurate to describe it as a transitory stage between the various ideological groupings of the post-Enlightenment (romanticism, materialism, et al.) and those diverging philosophical movements that only emerged in modernism proper (logical analysis, phenomenology, etc.). Thus, as a prominent figure within an essentially transitional period, Lotze's long shadow was, perhaps, predestined to gradually fade from the scene"(Sullivan, 2010)
It was within the atmosphere of the emerging obsolescence of Hegelian idealism, the division of academic disciplines into distinct domains of specialization, and the rise of analytic philosophy, that the logical positivists found their home. The logical positivists attempted to construct a foundationalist philosophy of science. Although the movement had numerous philosophers, its essence, particularly for our purposes, can be summarized rather simply:
"The fundamental thesis of modern empiricism [i.e. logical positivism] consists in denying the possibility of synthetic a priori knowledge" (H. Hahn, O. Neurath, R. Carnap, Wissenschaftliche Weltauffassung. Der Wiener Kreis, 1929).
Presupposed in the statement about synthetic a priori knowledge is a twofold distinction between a priori/a posteriori on the one hand, and synthetic/analytic statements on the other. A priori knowledge refers to purely non-empirical knowledge. Such knowledge is purely self-evident. A posteriori knowledge, on the other hand, is empirical knowledge. Likewise, synthetic knowledge is knoweldge whose predicate is not contained in the subject. An analytic statement, on the other hand, is a purely tautologous statement, whose predicate is contained in the subject. An example of the latter is A = A.
What the positivists thus denied is that there is any such thing as purely non-empirical knowledge. All utterances consist of either theh tautologies of logic, which are analytic and a priori, or the propositions of scientific inference, which are synthetic and a posteriori. There is no such thing as synthetic a priori knowledge. The significance of this belief for them is that it provided them with a means of rejecting metaphysical and religious statements as meaningless. Thus, for the logical positivists, scientific reasoning would be necessarily conceived as atheistic reasoning. They summarized this principle in what was referred to as the "verificationism." This is simply another way of saying that the only legitimate claims to knowledge are those whose content is empirically unverifiable. Propositions about morality, ethics and religion were thus out of the question, as they did not refer to empirically verifiable realities:
A.J. Ayer, for example, writes:
The presence of an ethical symbol in a proposition adds nothing to its factual content. Thus if I say to someone, "You acted wrongly in stealing that money," I am not stating anything more than if I had simply said, "You stole that money." In adding that this action is wrong I am not making any further statement about it. I am simply evincing my moral disapproval of it. It is as if I had said, "You stole that money," in a peculiar tone of horror, or written it with the addition of some special exclamation marks. … If now I generalise my previous statement and say, "Stealing money is wrong," I produce a sentence that has no factual meaning—that is, expresses no proposition that can be either true or false. … I am merely expressing certain moral sentiments.
It is worth noting at the outset that logical positivism has long since fallen out of fashion in academic philosophy. Indeed, its death knell was sounded in the early-to-mid 20th century. Nevertheless, it is puzzling that its influence is still very much felt in mainstream Western thought. Indeed, A.J. Ayer, one of the most important original advocates of the thought, as noticed this apparent paradox. He admitted of the majority of his philosophy of logical positivism that "nearly all of it was false" and in 1977, wrote:
"The verification principle is seldom mentioned and when it is mentioned it is usually scorned; it continues, however, to be put to work. The attitude of many philosophers reminds me of the relationship between Pip and Magwitch in Dickens's Great Expectations. They have lived on the money, but are ashamed to acknowledge its source"
Another important logical positivist, Moritz Schlick, wrote:
"When are we sure that the meaning of a question is clear? Obviously if and only if we are able to exactly describe the conditions in which it is possible to answer yes, or, respectively, the conditions in which it is necessary to answer with a no. The meaning of a question is thus defined only through the specification of those conditions...The definition of the circumstances under which a statement is true is perfectly equivalent to the definition of its meaning."
... a statement has a meaning if and only if the fact that it is true makes a verifiable difference.
(M. Schlick, 'Positivismus und Realismus' in Erkenntnis, 3, 1932).
Thus, for the logical positivists:
"Metaphysical statements are not empirically verifiable and are thus forbidden: they are meaningless. The only role of philosophy is the clarification of the meaning of statements and their logical interrelationships. There is no distinct "philosophical knowledge" over and above the analytic knowledge provided by the formal disciplines of logic and mathematics and the empirical knowledge provided by the sciences" (Logical positivism)
Let us undertake an analysis of the thought of the logical empiricists in general. While the term "logical empiricism" is oftentimes used interchangeably with that of logical positivism, logical empiricism arguably refers broadly to the trends within empiricism common to both the Vienna Circle in Austria and the Berlin Circle in Germany (only members of the former self-identified as logical positivists). Hopefully, this will begin to provide the reader some insight into the historical and genealogical roots of the trend of thought that regards scientific reasoning as inherently materialistic, mechanistic and atheistic.
We will first look at the historical context of the emergence of the movement broadly denominated "logical empiricism" and then descend to what particular philosophers in the movement taught. Arguably the most important group of logical empiricists were those of the Vienna Circle, who are more properly denominated "logical positivists." This group was headed by Moritz Schlick and the Ernst Mach Society. The other primary influence were the philosophers of the "Berlin Circle", from t he Berlin Society for Empirical Philosophy. Many of the latter disagreed vehemently with many of the doctrines of the former. The Berlin Circle oftentimes referred to those of the Vienna Circle as "positivists" with the intent of distancing their own teachings from them. The logical empiricists in general sported quite an impressive roster:
Another way of mapping the boundaries of logical empiricism is to list the specific philosophers who were centrally or peripherally part of it. Indeed, many of the most important philosophers of the mid-twentieth century were either members of the logical empiricist movement or associated with it in some way. Hans Hahn, Moritz Schlick, Rudolf Carnap, and Otto Neurath were leaders of the Vienna Circle, and Kurt Gödel regularly attended its meetings. The list of its members, visitors, and interlocutors is staggering. To name only a few, these include A.J. Ayer, Herbert Feigl, Philipp Frank, Hans Hahn, Carl Hempel, Karl Menger, Richard von Mises, Ernest Nagel, Karl Popper, W.V. Quine, Frank Ramsay, Hans Reichenbach, Alfred Tarski, Friedrich Waismann, and Ludwig Wittgenstein. Not all of these would admit to being part of the logical empiricist movement, of course, but a case can be made that all contributed to it. The Berlin Society for Empirical (or Scientific) Philosophy was, as stated, smaller but perhaps more influential. Led by Hans Reichenbach, it included, among others, Kurt Grelling, Walter Dubislav, Kurt Lewin, Richard von Mises, and Paul Oppenheim. Hempel took his doctorate in Berlin, working chiefly with Reichenbach until the latter was forced to leave in 1933. Hempel also spent time in Vienna and Prague as well. Of course, among the foremost associates of the Berlin Society was Albert Einstein, who was also in Berlin also until 1933 (Creath, 2013).
Because of the war in the 1930s, many of the important philosophers associated with these movements fled to America. The journal Erkenntnis, quoted above, originally one of the most important hubs of the philosophy, vanished in the 1940s. The exodus of the logical empiricists to America had quite an interesting philosophical and sociological effect:
Once in the U.S., these exiles were joined by the Americans Nelson Goodman, Charles Morris, W.V. Quine, Ernest Nagel, and, after the war, by Reichenbach's UCLA students Hilary Putnam and Wesley Salmon. Adolf Grünbaum can also be considered as clearly in the Reichenbach lineage. And Wilfrid Sellars was, in his early years, a close associate of Feigl. The American incarnation of the logical empiricist movement enjoyed generally good relations with the American pragmatists, not only because many of the logical empiricists had a strong pragmatist component to their philosophy, but also because the pragmatists and logical empiricists shared a common concern for empirical methodology in the service of social reform. Institutionally, the movement was represented in most major American universities, and such journals as Philosophy of Science (with Carnap and Feigl on the Editorial Board and Reichenbach and Schlick on the Advisory Board) and Philosophical Studies (founded and edited for many years by Feigl and Sellars) provided ample outlet for their publications. In addition, the Inter-Scientific Discussion Group was founded by Philipp Frank at Harvard. That grew into the Institute for the Unity of Science, called by some the Vienna Circle in exile. Meanwhile in Chicago the Encyclopedia of Unified Science was established with Neurath, Carnap, and Morris as its editors (Creath 2013).
By the 1960s, many of the original thinkers which had more or less identified with the movement had either recanted the beliefs associated with it, or simply abandoned it. By the next decade, the movement was more or less over. It is during the latter half of the 1970s that A.J. Ayer made the statements quoted above concerning its obsolescence.
One of the most important sociological elements of the context of the emergence of logical positivism, as we have noted before, was the emergence of hermenetically isolated scientific disciplines from philosophy (and indeed, all other disciplines); a process of specialization, which, as we have seen, had its roots in the thought of Hermann Lotze:
One long-term process with profound implications was the steady departure of the various sciences from philosophy to form autonomous disciplines. By early in the twentieth century mathematics, physics, chemistry, biology, and the social sciences were all pursued professionally and independently from philosophy. And psychology had just separated from philosophy or was in the process of doing so. Yes, there were polymaths who could and did pursue a science and philosophy professionally. Those were increasingly rare, but even single-discipline scientists did from time to time make philosophic-seeming pronouncements. But they did so from outside the field. This pattern of steady departures raised the pressing question: What sort of thing remained behind? Once mathematics and the empirical sciences all left, what was philosophy to be? (Creath 2013)
In light of this development, the role and nature of philosophy, particularly in relation to the hard sciences, was a peculiar preoccupation for the logical empiricists. Many philosophers of the period believed that philosophers had access to certain deeper truths than the hard sciences, and that it therefore had its own realm of investigation totally independent of scientific investigation. It was precisely this that the logical empiricists rejected. Carnap rejected such a conception of philosophy as "metaphysical," and therefore to be rejected.
The logical empiricists were eager to conceive of their enterprise as scientific and to engage in philosophy only insofar as it was also scientific. This science need not be an empirical one and it need not include all that was traditional in philosophy that had not been incorporated into the independent sciences. The decision to be scientific can hardly be the end of the story. It requires rather better and more detailed answers to questions about what scientific methods are, how the mathematical (and other apparently non-empirical sciences) fit together with the empirical ones, and what, more precisely, philosophy's role was (Creath 2013).
Logical positivists such as Schlick, Carnap and Hempel, who had started off as Neo-Kantians, had to grapple with developments in modern science which contradicted Kant's doctrines. Since Kant held that the world had to be represented as a Euclidean structure, the framework of which would constitute the bedrock of all future physics, positivists who had relied on Kant had to grapple with developments such as Einsteinian relativity and the co-ordinate development of non-Euclidean geometry, which would supplant the old. Geometry could no longer serve as the foundation according to which we would represent the empirical world, as Kant had desired (Creath 2013).
The demonstration that non-Euclidean pure geometrical structures were as consistent as Euclidean ones and that spaces can indeed be represented as a non-Euclidean manifolds were one half of the problem. The other half came when Einstein argued convincingly that physical space was best described as a non-Euclidean manifold of non-constant curvature. Plainly Euclidean geometry was not a feature of any future physics. Modern mathematical logic also posed a problem for other Kantian claims, but not in the same wrenching way(Creath 2013).
Under the scientific philosophy of the positivists lay a definite political motivation: The positivists, as good Enlightenment thinkers, held that the "evils" of the world were the result of bondage to 'metaphysical' patterns of thought. The irony, of course, is that the very notion of 'evil' requires the metaphysical category of ethics (which the positivists rejected as metaphysical and illegitimate), and so if the positivists were to be consistent, they would reject the very category which caused them to desire political reform in the first place.
Such ways of thinking might be exemplified in theology, in the racial hatreds of the day, in conceptions of property, and in traditional ideas about the “proper” roles of men and women in society. So to articulate a “scientific world conception” and to defend it against metaphysics was not just to express an academic position in the narrow sense. It was a political act as well; it was to strike a blow for the liberation of the mind. To articulate scientific methods and a scientific conception of philosophy was the essential first step in the reform of society and in the emancipation of humankind (Creath 2013).
In this respect, the logical positivists, as staunch modernists, were faithful heirs of the Enlightenment:
If all of this sounds like something out of the 18th century Enlightenment, the analogy was not lost on the logical empiricists themselves. André Carus has recently argued that this is exactly what Carnap had in mind in “explication” (Carus 2007). Neurath frequently drew parallels between the logical empiricists' anti-metaphysical program and the earlier Enlightenment ambitions. Certainly Kant had inveighed against the metaphysics of his time, and the anti-metaphysical tradition remained strong within the scientific community through the 19th century (Creath 2013).
The positivists, in wanting a strictly scientific conception of philosophy, found modern formal logic ready at hand. Departing from the Newtonian notion that scientific claims were those that could be inferred from experience, they drew on developments in the formal logic of their day in order to attempt to "specify the form of proper inferences, the form of an appropriate confirmation relation, and/or the structure of good reasons"(Creath 2013). The positivists had at their disposal the recently developed predicate calculus, thanks to logicians such as Gottlob Frege. Set theory and other forms of higher-order logic had recently become available as well. Russell had recently argued in "Our Knowledge of the External World" that logic was "the locus of scientific method in philosophy"(Creath 2013). Many positivists were likewise inspired by an interpretation of Wittgenstein's Tractatus, according to which "mathematics could be integrated into an overall empirical theory of the world. Wittgenstein also expressed a radical verificationism in the early 1930s in his conversations with Schlick, Waismann, and other members of the Vienna Circle"(Creath 2013). Creath outlines the central concerns of the positivists as:
1) The relations between "empiricism, verificationism, and anti-metaphysics" (Creath 2013)
2) "the logical empiricists' treatment of logic and mathematics as analytic" (Creath 2013)
3) "the united of science and reduction"(Creath 2013)
4) Questions surrounding probability.
First, we will deal with the relations between empiricism, verificationism and anti-metaphysics. One of the central concerns of the positivists had to do with the question of whether or not scientific investigation rested upon something other than experience. Before the positivists, it was generally agreed, and taken for granted by Frege, Russell and Wittgenstein, that logic and mathematics, as consisting entirely of purely analytic truths, did not rest on experience. The positivists were inspired by the verificationist position taken by the early Wittgenstein in particular, that logic and mathematics consisted of nothing but tautologies, and that sensible synthetic claims consisted only of those which could be confirmed by experience. According to such a strict verificationism, however, many notions ordinarily considered 'scientific' would have to be dispensed with, such as "laws" of nature. Some positivists, such as Moritz Schlick, simply admitted that propositions about 'laws' of nature did not refer to such at all, but were instead "principles of inference"(Creath 2013). Other positivists, unwilling to take what they considered an inordinately radical position, such as Han, Neurath, Carnap and Philipp Frank, modified their verificationism instead (Creath 2013). Indeed, Creath goes as far as denying that Carnap was in any meaningful sense a verificationist at all.
Positivists proposed numerous models of verification, each time succumbing to failure. Verificationists, Creath notes, attempted to link semantic meaningfulness with empirical confirmation. The positivists likewise attempted to develop philosophically sophisticated accounts of empirical confirmation. The accounts of verification developed by Ayer in 1936, and Carnap in 1956, remain the most well-known (Creath 2013). Ayer's emphasis was on synthetic sentences. For Ayer, "Confirmation is a feature that applies to sentences (or groups of them) and not to sub-sentential parts, and for an empiricist the content that a synthetic sentence has would be empirical content"(Creath 2013). For a sentence to have such empirical content, it must either imply an observational sentence "or add to the observational content of some other sentence...That is, the conjunction of A and B should imply some observation sentence not implied by B alone"(Creath 2013). Carnap argued that confirmation is not strictly a characteristic of whole sentences, but a characteristic of terms within those sentences.
Whatever the case may be, it is obvious that the positivist position is self-refuting. The positivists claimed that all sentences are either analytic or synthetic. The verification principle is clearly not an analytic statement. If it were, it would be true by virtue of its meaning and therefore trivial. It is not true by virtue of its meaning, because there are people who disagree with it. Furthermore, if it were true by virtue of its meaning, it would be a tautology, which it is clearly not. It is also not a sentence which is itself empirically verifiable. Therefore, by positivist standards, it is a nonsense statement which must be rejected. Positivism in general can therefore safely be rejected as metaphysical nonsense, as it ought to have been regarded by the positivists themselves (as it oftentimes was).
Carnap addresses the charge of self-refutation in his "Philosophy and Logical Syntax." He argues that the verifiability criterion of meaning occupies the realm of part of a meta-language, and that this standard is therefore not a component of the language itself. The verificationist criteria of meaning, therefore, is not self-refuting. Rather than seeking to defend positivism from the infinite regress to which such a position obviously leads (since the meta-language would require a meta-meta-language by which the meta-language is itself governed, and so on and so forth ad infinitum) Carnap took up a position astonishingly similar to that of some of the pragmatists, according to which there is no definitively "correct" logic.
Perhaps more precisely each of the various versions of empiricism (including some sort of verificationism) is best understood as a proposal for structuring the language of science. Before tolerance, both empiricism and verificationism are announced as if they are simply correct. Correspondingly, what Carnap called metaphysics is then treated as though it is, as a matter of brute fact, unintelligible. But what is announced thus dogmatically can be rejected equally dogmatically. Once tolerance is in place, alternative philosophic positions, including metaphysical ones, are construed as alternative proposals for structuring the language of science.
None of them is the uniquely correct one, and no theoretical argument or evidence can show that it is. Nor can theoretical arguments or evidence show that it is false. Neither proposals nor languages are the sort of thing to be true or false. Instead, proposals call for practical decisions and practical arguments rather than for theoretical reasons or evidence. Carnap believes that there are indeed very good practical reasons for adopting the proposal of verificationism, for choosing a language of science in which all substantive (synthetic) claims can, at least in principle, be brought before the court of public experience. The reason is that if we do not require this, the result is “wearisome controversies” that there is no hope of resolving. That, he thinks, is the sad history of attempts to get beyond science, and it is just too painful (Creath 2013).
Carnap's own preferred 'language' is one in which there are "no synthetic sentences that are both unverifiable and meaningful"(Creath 2013). He accepts that languages which dissent from such a view are no less legitimate than the one he has proposed. Adoption of this or that language is merely a matter of preference, and he prefers his own language because he believes it is the most pragmatically useful.
Thought of in this way the verifiability principle does not describe natural language, it is not intended to. It is intended to reform language to make it a more useful tool for the purposes of science. Carnap is under no illusion that natural languages are free from metaphysics. Nor is he under the illusion that defenders of the sort of metaphysics he targets will readily step up to the challenge of presenting precise rules of grammar and inference.
There is one other change that tolerance brings to Carnap's own vocabulary. Before tolerance, verificationism is stated in such a way that violations would count only as unintelligible gibberish. With tolerance in place, Carnap is prepared to imagine non-empiricist languages, though of course he thinks they are very unwise. So instead of saying that violations of these principles, that is, the sentences in non-empiricist languages, are meaningless he says that they are empirically meaningless which has a very different flavor. There is no weakening of his defense of empiricism, but it is put on a somewhat different footing (Creath 2013).
How unlike the common caricature of the logical positivists as inordinately tough-minded positivists by whose standards hardly anything can be admitted to the status of knowledge! Indeed, Carnap's "tolerance" was quite legendary, as he was known even for admitting the notorious continental philosophers as (at least potentially) legitimate interlocutors:
"Before a particular meeting got under way, a friend and I were chattering about metaphysics and, no doubt hoping to impress Carnap with our commitment to the tough-minded ideology he was noted for espousing, we expressed our utter derision for some claim by Heidegger. Carnap's response was immediate: "Tolerance, boys, tolerance." It stopped us in our tracks"(Aune, 1998).
Carnap's 'tolerance' of Heidegger here is quite important, both in its own right insofar as a philosophy of tolerance is self-defeating, and insofar as it is a concession to Heidegger's very own philosophy. Heidegger was more or less a presuppositionalist among non-Christians, and his philosophy requires that someone like Carnap cannot pretend to merely neutral presuppositions. But more on this later.
Let's look at what was taught by specific logical empiricists, as well as those who are oftentimes associated with the movement, but whose views do not necessarily strictly correspond with stereotypes about positivists.
Carnap made numerous important contributions to philosophy of science and logic. He rejected metaphysical utterances as meaningless on the ground that they could not be justified through experience; in this respect, his beliefs correspond to what we have come to learn about positivists.
"He asserted that many philosophical problems are indeed pseudo-problems, the outcome of a misuse of language. Some of them can be resolved when we recognize that they are not expressing matters of facft, but rather concern the echoice between different linguistic frameworks. Thus the logical analysis of language becomes the principal instrument in resolving philosophical problems. Since ordinary language is ambiguous, Carnap asserted the necessity of studying philosophical issues in artificial languages, which are governedby the rules of logic and mathematics. In such languages, he dealt with the problems of the meaning of a dstatement, the different interpretations of probability, the nature of explanation and the distinctions between analytic and synthetic, a priori and a posteriori, and necessary and contingent statements"(Murzi)
For Carnap, a scientific theory was an "axiomatic formal system"(Murzi) consisting of:
a formal language, including logical and non-logical terms;
a set of logical-mathematical axioms and rules of inference;
a set of non-logical axioms, expressing the empirical portion of the theory;
a set of meaning postulates stating the meaning of non-logical terms, which formalize the analytic truths of the theory;
a set of rules of correspondence, which give an empirical interpretation of the theory(Murzi)
For Carnap, one of the most important functions of philosophy was to demonstrate the differences between different kinds of sentences. A scientific theory, for Carnap, would consist of symbols as well as syntactical rules whose purpose was to ensure that the sequence of symbols which constituted the scientific theory would constitute a well-formed formula. A scientific theory which did not follow from the syntax would be a meaningless sentence or set of sentences. Important for Carnap was the distinction between logical and non-logical terms of the theory. Logical terms consist of the sort of terms we're used to in formal logic, such as connectives, quantifiers, etc. This also included mathematical symbols such as numbers and integrals.
On the other hand, non-logical symbols consist of two sorts:
These non-logical symbols refer to the actual empirical data which constitute the object of study. Furthermore, Carnap distinguished between 4 sorts of formulae:
1) Logical statements - these do not contain non-logical terms. They are purely analytic and a priori
2) Observational statements - these contain "observational terms but no theoretical terms"(Murzi)
3) Purely theoretical statements - these "contain theoretical terms but no observational terms"(Murzi)
4) Rules of correspondence - these contain "both observational and theoretical terms"(Murzi)
How exactly do we articulate the distinction between observational and theoretical terms? This distinction, it ought to be noted, was essential not only for Carnap's philosophy of science, but for positivism in general(Murzi). He articulates this distinction in
"Philosophical Foundations of Physics" in terms of the distinction between empirical laws and theoretical laws(Murzi). Empirical laws deal
"with objects or properties that can be observed or measured by means of simple procedures. This kind of law can be directly confirmed by empirical observations. It can explain and forecast facts and be thought of as an inductive generalization of such factual observations. Typically, an empirical law which deals with measurable physical quantities, can be established by means of measuring such quantities in suitable cases and then interpolating a simple curve between the measured values. For example, a physicist could measure the volume V, the temperature T and the pressure P of a gas in diverse experiments, and he could find the law PV=RT, for a suitable constant R"(Murzi).
So an empirical law, for Carnap, was a kind of inductive generalization about the behavior of observable objects or properties. A theoretical law, however, concernrs properties or objects which we can only infer rather than directly measure. We go from empirical laws, which constitute inductive generalizations about observable entities or properties, to theoretical laws, which are more like hypotheses (Murzi). "While an empirical law can explain and forecast facts, a theoretical law can explain and forecast empirical laws. The method of justifying a theoretical law is indirect: a scientist does not test the law itself but, rather, the empirical laws that are among its consequences."(Murzi).
The distinction seems intuitively plausible, so far as it goes. However,
Carnap admits...that the distinction is not always clear and the line of demarcation often arbitrary. In some ways the distinction between observational and theoretical terms is similar to that between macro-events, which are characterized by physical quantities that remain constant over a large portion of space and time, and micro-events, where physical quantities change rapidly in space or time(Murzi).
As noted before, Carnap advocated the principle for which logical positivism is perhaps most famous: the verifiability principle, . According to this principle, a synthetic statement is only meaningful if its content is verifiable. We have already dealt with this principle and will not deal with it in Carnap. Suffice it to say that it was not long after Carnap's acceptance of this principle that he argued for the position we mentioned before; namely, that "the significance of a term becomes a relative concept: a term is meaningful with respect to a given theory and a given language. The meaning of a concept thus depends on the theory in which that concept is used. This represents a significant modification in empiricism's theory of meaning"(Murzi). He thus ends up with a highly relativistic and pragmatistic conception of theoretical language hardly worthy of someone as preoccupied with a rigorously scientific conception of the world.
Feigl and Wilfred Sellars summarize their empiricism in Readings in Philosophical Analysis:
"The conception of philosophical analysis underlying our selections [they say] springs from two major traditions in recent thought, the Cambridge movement, deriving from Moore and Russell, and the Logical Positivism of the Vienna Circle (Wittgenstein, Schlick, Carnap) together with the Scientific Empiricism of the Berlin group (led by Reichenbach). These, together with related developments in America stemming from Realism and Pragmatism and the relatively independent contributions of the Polish logicians, have increasingly merged to create an approach to philosophical problems which we frankly consider a decisive turn in the history of philosophy" (Quoted in Aune, 1998)
Though oftentimes associated with logical empiricism specifically, it is clear that Feigl was associated much more broadly with Anglo-American philosophical movements whose aim, to one degree or another, was to conceive of philosophy as a handmaiden to scientific investigation. Its purpose was not that of metaphysical speculation for its own sake, but a practical investigation into how things hang together, so to speak. This included, by this account, the early analytic philosophy of G.E. Moore and Bertrand Russell, the logical empiricism of the Berlin Circle, and the logical positivism of the Vienna Circle, as well as the pragmatists and the Polish logicians (at least one of whom, namely, Alfred Tarski, exerted an important influence on logical empiricism, broadly construed to include both the positivists of Vienna and the empiricists of Berlin). Like Carnap, Feigl insisted that factual claims be tested according to a verifiability or confirmation criterion: No statement has any meaning unless its truth can be empirically confirmed.
Furthermore, like Carnap, he upheld the distinction between analytic a priori and synthetic a posteriori statements, and considered these two kinds of sentences to be the only legitimate claims, rejecting as nonsensical and 'metaphysical' claims to synthetic a priori knowledge. So far as synthetic a posteriori justification was concerned, Feigl admitted only inductive inference and observation to the table. Though initially an ardent logical positivist, he later came to entertain a great deal of uncertainty about what he believed.
Otto Neurath was another important figure in the history of logical empiricism. Over and against the foundationalism of Carnap's Aufbau, Neurath had a more pragmatic and coherentist understanding of the nature of scientific knowledge. Scientific investigation was a unified endeavor in which numerous varied disciplines coordinated their efforts and the conclusions they had reached in their own scientific discipline into a unified whole. Neurath emphasized the interpersonal nature of language, prediction and justification. Language is never purely monological. It is developed within the intersubjective realm. The intersubjective nature of language is a more particular species of his pragmatic project broadly considered. That is, we do not merely interact with other humans, but with a definite world. For Neurath, the language of the intersubjective realm was one and the same with the language and interaction of the physical realm. It is for this reason that he termed his understanding of such language as "physicalist." His intersubjective understanding of the nature of language and rationality has drawn appropriate comparison with that of Wittgenstein:
Objectivity features prominently in the private language argument. Both Neurath's argument and Wittgenstein's earlier one are laid out for the case of an individual epistemic agent understanding himself before he needs to understand others (Uebel 1995b). For both, the constancy and consistency of language use is paramount. It can only be ensured by an intersubjective, that is, objective and social, language, namely the language of physicalism, about ‘spatio-temporal structures’. For Wittgenstein, especially in the Philosophical Investigations, the social dimension of language guarantees its extrinsic character and therefore its proper justification, the normative condition of possibility and intelligibility of success, and likewise for the more general case of rule-following. The scope of Neurath's argument is more particularly directed to the case of scientific language in the scientific community.
The notion of private language argument is typically associated with the later argument by Wittgenstein in Philosophical Investigations to the effect that a private language is logically impossible for an individual to use consistently and for others to understand. By private language, Wittgenstein means a language with words whose meaning is essentially dependent on the inner experience or individual consciousness of a subject. In a previous version from 1929, Wittgenstein refers to the primacy of our public everyday language about physical things over a language of immediate sensations. In the 1951 version the language is dependent on the public social institutions of language-games and their rules. A private language is, by contrast, impossible because to use it requires following its rules, which in turn requires a private modality of rule-following, and this, Wittgenstein claims, is incorrect(Cat, 2011).
In opposition to the notion of synthetic a priori knowledge, which as we have seen was incompatible with the philosophy of the positivists, was the notion that "revisable theoretical scientific statements should stand in appropriate logical relations to unrevisable statements about elementary observations (data), called 'control sentences' or 'protocol sentences'. Such relations would provide theoretical terms with cognitive meaning or sense, and theoretical statements with verification"(Cat, 2011).
It ought to be noted that in addition to the emphasis upon verifiability, experience and empiricism, among the positivists, was the emphasis on language. We have seen that one of Neurath's central concerns was not merely the conditions under which objective knowledge could be had, but the question of the intersubjective communicability of this objective knowledge.
The ‘linguistic turn’, as it is known, was adopted as a philosophical tool in order to explicate the rationality, and the objectivity—that is, inter-subjectivity—and communicability of thought. Lacking the transcendental dimension of Kant's metaphysical apparatus, attention to language extended to non-scientific cases such as ordinary language philosophy in Oxford and to literary texts in the Continent. In the context of logical empiricism, the formal dimension of knowledge was thought to be manifest particularly in the exactness of scientific statements. For Schlick, knowledge proper, whether of experience or transcendent reality, was such only by virtue of form or structure—‘only structure is knowable’. For Carnap, in addition, the formal dimension possessed distinct methodological values: it served the purpose of logical analysis and rational reconstruction of knowledge and helped expose and circumvent ‘pseudo-philosophical’ problems around metaphysical questions about reality (his objections to Heidegger appealed to failures of proper logical formulation and not just empirical verification). In 1934 he proposed as the task of philosophy the metalinguistic analysis of logical and linguistic features of scientific method and knowledge (the ‘thesis of metalogic’). For Neurath, this approach helped purge philosophy of deleterious metaphysical nonsense and dogmatism, and acknowledged the radically social nature of language and science (Cat, 2011).
Neurath's emphasis on the intersubjective element of knowledge is best understood in opposition to the arguments of Carnap's Aufbau, discussed earlier. In this work, Carnap had investigated the origin of intersubjective knowledge, beginning with the individual subject. For Carnap, knowledge is irreducibly private. It is individuals who possess knowledge, and so it follows that we would investigate the origin of this knowledge in the individual's experience.
In particular it was supposed to capture how experience is central to meaning and method; that is, how it is responsible for the intelligibility and acceptability of our beliefs. All we need is connecting-statements or rules that link any statement to experiential statements—translation rules, originally biconditional ‘constitution sentences’, and subsequently, in the late 1930s, weaker conditional ‘reduction sentences’ and ‘semantic postulates’, or ‘bridge principles’. The inclusion of terms and statements in the system of science by this method excluded all nonsensical speculative statements. It provided a verification criterion not only of testing but also of cognitive significance, or meaning. Carnap stated in that vein that ‘science is a system of statements based on direct experience’ (1932/1934)(Cat, 2011).
To put it simply: knowledge begins in the individual's experience, and a faithfully scientific conception of philosophy provides a language for the communication and systematization of such knowledge. Such a position was understood immediately by fellow members of the Vienna Circle as having enormous philosophical implications:
In spite of the range of alternatives considered, the Aufbau's main focus on an empiricist, or phenomenological, model of knowledge in terms of the immediate experiential basis was quickly understood by fellow members of the Vienna Circle as manifesting three philosophical positions: reductionism, atomism and foundationalism. Reductionism took one set of terms to be fundamental or primitive; the rest would be logically connected to them. Atomism, especially in Neurath's reading, was manifest semantically and syntactically: semantically, in the analyzability of a term; syntactically or structurally, in the elementary structure of protocols in terms of a single experiential term—‘red circle here now’—; it also appeared in the possibility of an individual testing relation of a theoretical statement to one of more experiential statements. (Cat 2011)
Of particular interest for us is Carnap's foundationalism. Cat notes the Cartesian historical roots of this element of Carnap's philosophy. For Descartes, as for Carnap, we ought to take as our starting point an infallible foundation (hence the term) which is itself properly basic and does not require external justification. It is from this basis that we then infer subsequent truths, which are deduced infallibly from this basis. Unless the beliefs we deduce can be inferred necessarily from this foundation, they cannot count as knowledge. Neurath likewise rejected Carnap's apparent subjectivism. Since knowledge is intersubjective, it can never be merely private. Indeed, it is because knowledge is public and intersubjective that communication is possible at all. "In order to use experience reports to test and verify even one individual's own beliefs over time, private instantaneous statements of the form ‘red here now’ will not do"(Cat 2011). In place of Carnap's phenomenalism, which Neurath believed would result in solipsism, was the latter's thesis of "physicalism", according to which "the unity, intelligibility and objectivity of science rests ons tatements in a language of public things, events and processes in space and time - including behavior and physiological events, hence not necessarily in the technical terms of physical theory"(Cat 2011). It ought to be kept in mind, however, that although Neurath referred to his own philosophy of intersubjective communication as 'physicalism', he is not using the term as synonymous with ontological materialism, as it is often used nowadays in philosophical discourse.
What was Neurath's motivation for this? His desire was to create an intersubjective language for a scientific conception of science that would be able to communicate with precision the sort of objective, mathematical and quantitative measurements so essential to scientific investigation. In this, he is at one with Carnap, who likewise believed that
"only the structural or formal features, in this case, of exact mathematical relations (manifested in the topological and metric characteristics of scales), can guarantee objectivity. After the Aufbau, now the unity of science rested on the universal possibility of the translation of any scientific statement into physical language - which in the long run might lead to the reduction of all scientific knowledge to the laws and concepts of physics"(Cat 2011)
For Neurath, in place of Carnap's subjectivistic and phenomenalistic doctrine of private knowledge was the doctrine of protocol statements. The purpose of the study of protocol statements, for Neurath, was to articulate what would count as scientific evidence within the context of an empiricist epistemology "by specifying conditions of acceptance of a statement as empirical scientific evidence"(Cat 2011). Neurath's intention in this was to avoid Carnap's foundationalism, subjectivism, atomism and reductionism (Cat 2011). Cat notes that Neurath's paradigmatic example of such a sentence was:
"Otto's protocol at 3:17 o'clock: [Otto's speech-thinking at 3:16 was: (at 3:15 o'clock there was a table in the room perceived by Otto)]."
This has obvious advantages over Carnap's paradigmatic protocol statement, "I see a red circle here now." Neurath's specifies that the person perceiving the table is Otto. The implication is that Otto is distinct from other people who also exist. So we have an example of how Otto's protocol statement implicitly recognizes the public nature of knowledge. This is quite opposed to Carnap's subjectivistic, purely phenomenalistic, 1st person account. Cat notes that the time and spatial location explicitly enunciated in Neurath's sentence provides a helpful alternative to Carnap's overly simplistic sentence.
Neurath's articulation of a protocol sentence was part of an overall project to create a unified, intersubjective, agreed-upon language among scientists that was free of metaphysics. More interestingly yet, Neurath was opposed to the use of subjectivistic language such as "I", because the self, as Kant and Hume had ably and famously demonstrated, could not be proven to exist empirically. All we are conscious of is pure experience, never an indivisible, substantial 'self.'
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