I. The Dismantling of Logical Positivism Noretta Koertge
In this course we will be discussing a variety of post-positivistic theories of scientific progress. Since their most salient shared feature is a rejection of logical positivism, let's begin by quickly sketching what they were reacting against. [For a fuller account of what he calls "the received view" see Fred Suppe's The Structure of Scientific Theories. The philosophical background to the program of the Vienna Circle is analyzed in A. Coffa, Towards the Vienna Station.]
As the name indicates, logical positivism (or logical empiricism) assumes that knowledge comes from the senses (reason plays an important processing role, but does not provide content). One job of the philosopher is to subject belief systems to logical analysis, separating out positive knowledge claims from meaningless babble or unverified speculation. When they turned to science, the logical positivists spent a lot of time axiomatizing scientific theories or at least debating how they should be axiomatized.
There was general agreement that the structure of science was roughly represented by a "layer-cake model". (This label was originally introduced by a critic, Feyerabend, as a term of disparagement, but Feigl, who had helped coin the phrase "logical positivism" in 1931 [Encycl. of Phil.] willingly accepted it [Minn.III]).
On this model, science consists of three layers. On the bottom are singular observation reports [positivists argued amongst themselves about the exact nature of these. Should they describe sensations or pointer readings?]; in the middle are empirical generalizations, often called "laws", such as the laws named after Kepler, Boyle, Hooke, Galileo, etc. Topping off the cake are theories, such as the Kinetic Theory of Gases, Quantum Theory, Electromagnetic Theory, etc.
Deductive inferences lead from the top of the cake down to the lower level, thus permitting us both to explain past events (by showing how they are subsumed under "covering laws") and to predict ones in the future, events which have not yet been observed.
Inductive support percolates up through the structure - the observation reports support the laws and the laws in turn support the theories which unify them.
[--- Unable To Translate Graphic ---]
The general flavor of this model is quite reminiscent of Whewell's Inductive Tables where he charts the historical development of sciences such as optics, astronomy and mechanics or Bacon's description of science as the ascent of a "ladder of axioms" through induction. However, what was new about the logical positivists' account was their insistence that the layers of the cake be characterized in terms of language. According to the logical positivists, scientific systems should be expressed using two different languages. The top layer would be expressed in theoretical language, using terms such as "electron" or "atomic number", while the lower level would be written in observation language, using terms such as "red" or "weighs two grams". [Again I will ignore the debate about whether the observation language should be phenomenalist or physicalist.]
This two-language account introduced a sharp epistemological hiatus between the various levels of science - how could one ever hope to get knowledge about theoretical entities? There had always been some concern about how one could get knowledge about underlying mechanisms - recall the Atomic Debates in the mid-nineteenth century or Descartes' discussion about whether one could discover or infer the mechanical micro-process which would explain refraction or magnetism - but the positivists both dramatized the problem and added an entirely new wrinkle: Could we even be sure that a hypothesis which purported to describe micro-processes or unobservable properties was even meaningful?
The history of the development of the positivists' approach towards the problem of meaning is a long and complicated one [see Coffa], but many of their attitudes are encapsulated in the morals they drew from the replacement of Newtonian mechanics by Relativity Theory. It was perhaps understandable that a respectable scientific theory might make inaccurate predictions in unfamiliar domains, which involved unusually high velocities or large gravitational forces. But what was shocking was that Newtonians had uncritically made assumptions about the nature of space and time which could not even be tested and, hence, were without empirical significance. And any claim which could not be tightly connected to experience, according to the positivists, was also without cognitive significance. So Newton's talk about space and time was not just unverified, or even false - it was unverifiable in principle, and hence meaningless in a strict sense. to prevent future fiascos, scientists should always operationalize their theoretical claims. No one can guarantee ahead of time that an untested scientific hypothesis is true, but through philosophical analysis we should at least be able to guarantee that it has meaning!
For over thirty years there was broad support for the layer-cake model amongst philosophers of science as well as wide agreement about what the pressing problems were:
1) to give a precise account of how theoretical terms gained their meaning (was it through operational definitions, reduction sentences, implicit definitions, or ?)
2) to determine whether theoretical terms refer and if so, to what? (the problem of realism)
3) to describe an inductive logic which in principle would permit the calculation of the degree of reasonable belief which should be assigned any meaningful scientific hypothesis
4) to give a model of explanation which did not invoke metaphysical notions such as causality or intelligibility.
There was also broad agreement on the types of solutions which would be acceptable. The philosophical accounts of science should be logical and normative, not psychological or descriptive. Thus, the problem of how science develops never was on the agenda. To the extent that the growth of science was rational, it was assumed to occur by a sort of sedimentation process laying down successive layers of statements of increasing generality. There might be temporary debates about items on the very top of the cake or in new domains out at the side, but the growth of science should be a rather orderly process of accumulation. The question of where new concepts or hypotheses came from was an issue for psychology, not for philosophy - hence, Reichenbach's much quoted distinction between the context of discovery (of interest only to the psychologist or historian of science) and the much more important context of justification (of interest to the philosopher, working scientist and any one who wishes to apply science).
A detailed story of the decline of logical positivism has yet to be told. (In Stoppard's play Jumpers, the character George Moore says that at one moment in history the onus of proof passed from the atheist to those who wished to defend theism, "...quite suddenly, secretly, the noes had it".) Perhaps something similar happened with logical positivism. There are still many philosophers of science (perhaps even a majority) who work very much in a soft positivist tradition. However the central problems of the positivist program have been quietly de-coupled and the constraints on their solutions slowly relaxed. Thus people today who work on explanation may invoke causes; some confirmation theorists deal with subjective degrees of belief; people who theorize about meanings may invoke prototypes, metaphors or Gestalts. The rigid theory/observation distinction has largely been dropped, at least as a tool of analysis. This has opened the way for the so-called 'semantic view' of theories which posits abstract set-theoretic structures which are then instantiated by various physical systems.
But the most exciting philosophical developments have arisen out of conscious attempts to provide radical alternatives to the whole positivist program. The purpose of this course is to present these alternative philosophical theories in detail and to describe the special strengths and weaknesses of each. These theories of scientific progress vary so enormously that the philosophers cannot be considered a school, or even a tradition (though labels such as "historicist" or "naturalist" have been proposed). However, I think they do share certain assumptions.
First of all, their views are anti-foundationist. Science does not and cannot grow through monotonic accumulation of positive knowledge claims. Whereas the logical positivists viewed the Einsteinian Revolution as a methodological indictment of Newtonian scientists - a sort of "never again" cautionary tale - Popper saw it as just the latest example of how critical debate could cause us to revise our most fundamental assumptions and called for "Revolution in Permanence". Kuhn took scientific revolutions to be a crucial feature of the development of science and emphasized how extensively they shook up our pictures of the world. (No layer cake could hope to survive the tremors of a Kuhnian Gestalt switch.)
So science was fallible through and through. And no amount of positivistic epistemological puritanism would help because observations were necessarily theory-laden and theoretical systems were in turn inevitably influenced by metaphysical and ontological assumptions of a non-empirical nature.
As a consequence any useful picture of a scientific system had to be much richer and more interactive than the austere layer cake model. And since no elements in the system were privileged and could be revised, it was also important to develop a sophisticated account of the development of the system over time. What has emerged is a general conception of science which I will call the "tapestry model" (or perhaps I should say models because, as we will see later, there are important differences amongst these past-positivists).
Surrogates of the elements of the old layer cake model still reside in the center (although the language-based theory/law distinction is no longer important). But they are surrounded by other items which interact with them in all sorts of ways. Thus theories may gain meaning from favored models and analogies not just through their connection to observations. The 'empirical' testing and confirmation of the central theories is a complex process which depends not just on observation reports but also on all sorts of other theories, including theories about how instruments work and theories about other causally relevant phenomena.
In short, the theories and observation reports of any science reside in the center of a complicated fabric which is constrained on all sides by a 'framework' which is itself subject to revision. There is no foundation and the paths of transmission of meaning, evidential support, and critical appraisal run horizontally as well as vertically.
The general problem for post-positivist philosophers will be to describe in more detail patterns within the tapestry and the processes by which it is woven and re-woven. (The problem of describing the development of science.) Some will specialize in the role of heuristics - no longer will it be an oxymoron to speak of a "logic of discovery". Others will argue that even the above model is too austere and study effects of scientific institutions on the progress of science.
I have indicated how the philosophical accounts we will be discussing are post-positivist, but in what sense can we say they are theories of progress? If science has no foundations, if metaphysical and methodological frameworks themselves can be revised through scientific inquiry, where can we find an Archimedean point from which to measure progress? Sure, science changes but in what sense does it progress? The issue of the rationality of scientific change is a major problem for the post-positivistic philosophers whom we will study and we will discuss some of their solutions. I think it is fair to say that all the philosophers we will study believe that there is an objective notion of cognitive progress and in science would consider it a criticism if it could be shown that their theory of science led to the relativist's conclusion that theory change was primarily governed by fashion, ideology, or politics. (Not all post-positivists eschew relativism, but i have not included them here.) Whether our believers in rational progress succeed in avoiding relativism - and exactly what they mean by relativism - remains to be seen, of course.