Notas para un esquema de la filosofía de la ciencia contemporánea

Abstract

These notes propose a principle of order for the philosophy of science of the last two decades. They do not intend to include the whole subject, since, above all, they contain no reference to the “continental” European trends. Behind the variety of topics and views in the contemporary philosophy of science the careful observer can perceive a pattern designed by epistemology which determines solutions as well as problems in this field. This may possibly justify our decision to restrict our attention to strictly epistemological positions developed during the last decades. We shall refer here, essentially, to what are usually considered as three conflicting trends of thought: 1) Scientific realism, which in one version or another is defended by such philosophers as G. Maxwell, Popper, Bunge, Feyerabend, and J.J.C. Smart; 2) the philosophy of science of linguistic or Wittgensteinian inspiration, represented by such thinkers as N.R. Hanson, S. Toulmin, and S. Scriven; 3) the philosophy of science of T.S. Kuhn and his disciples.
We shall use the expression “the classicists” to designate the philosophers of science of the years prior to 1950, and “the contemporary writers” in referring to the philosophers of science of the last 20 years. Both the classicists, among whom one finds Popper and Carnap, as well as the contemporary writers, agree that science is the paradigmatic case of knowledge; but there is a point of agreement among the classicists which the contemporary writers unanimously reject. It has to do with the principle of semantic uniformity which maintains that every statement of an empirical theory is an affirmation. In an affirmation, the distribution of reference to its non-logical terms precedes the determination of its truth-value; an affirmation may be false. Now, then, there are statements of empirical theories —such as the principle of inertia— which are implicit definitions, and implicit definitions partially identify their object as that which possesses the properties in question and therefore they cannot predicate anything false of it. To say of a statement that it is a conjecture is to say that it is at least possible that what the statement attributes to its object may not be one of its properties; therefore it is unacceptable to think of implicit definitions as conjectures. For its contemporaries, the non-conjectural character of the maximum scientific principles is an indisputable fact, just as these principles, far from being tautologies with no empirical content are the fundamental principles of our knowledge of nature. The contemporary writer embarks upon a search for an epistemology which let him understand how it is possible that there may be statements with an empirical content, that is to say, which are syntetic, and which nevertheless are irrefutable, that is to say, necessary. The contemporary philosophy of science is in great part a return to the problems and solutions of Kant. This is especially true in the case of Wilfrid Sellars.
For this philosopher, the images which man constructs of himself and his world fall into two basic categories: the “manifest image” and the “scientific image”. An essential characteristic of the manifest image is that in it the categorical refinement has been developing without recourse in any instance to the postulation of unobservable entities. The scientific image on the other hand is what man has been constructing through the postulation of subvisible or invisible entities. The manifest and scientific images make an effort to be images of the same universe, even though it seems to become more and more clear that neither of them can be adequate representations of the same reality.
The thesis that the scientific object is that which really exists and the manifest object that which does not exist is the position of the scientific realism defended by Sellars. For Kant, the primary qualities, the spatial geometric forms, are transformed into forms of sensibility. In Kant it is not possible to represent any trait of reality, the thing in itself; thus, Kant invites the idealistic rejection of the external world. From Kant on, philosophy takes a seriously erroneous course which it is necessary to correct through a process in which, according to Sellars, modern philosophy is now engaged.
For Kant and Sellars, the peculiar structure of sensibility does not consist of mere receptivity, but also incorporates an active faculty which organizes the variety or multiplicity of sensorial data. On the other hand, the understanding, through the categories, permits us to identify a sector of the space-temporarized multiplicity as, let us say, a physical object. Referring to the manifest image group, Sellars point out: “there are many principles concerning physical objects and our perception of them (we might call them ‘categorial principles’) which are constituents of the concepts in whose terms we perceive the world”.
Sellar seems to be pointing out that these principles lack the character of affirmations upon rejecting the Popperian thesis of Feyerabend, who looks upon these principles and the conceptual framework they constitute as a conjecture or theory (refuted quite some time ago).
The categorial principles of Sellars, the conceptual principles of Hanson, the exemplars of Kuhn, represent stages through which the contemporaries have attempted to identify, within the complexity of ingredients which make up a theory, the element which fulfils the function of giving form to the world of experience as a perceptible world.
Thus far, the return to Kant called for by Sellars. For Kant, nothing can be known of the itself. For Sellars, on the other hand, it is possible to know a great deal of what really exists. The scientific image has as its object the structure of the world of things in themselves, a structure in which the scientific theories converge. Science, Sellars would say, is the measure of all things: of those which are to the extent they are, of those which are not to the extent they are not.
Just as Sellars, Hanson, Toulmin, and Kuhn concede a dominant role in their philosophy to the Kantian categorial theme, but form a different philosophical perspective partially inspired in linguistic philosophy.
There is a type of argument associated with the so-called “argument of the paradigmatic case” which plays an important role in the Wittgensteinian focus on the problems we are confronting. According to the linguistic philosopher, what a term means is neither more nor less than what I (or any other speaker of my language) have been taught it means. Correct use will constitute (or, at least, will determine) its meaning. But it would seem clear that the word “table”, for example, normally acquires its meaning in contexts wherein it is ostensively associated with certain paradigmatic objects. The linguistic philosopher thinks it would be absurd to raise in these contexts any doubt concerning the fitness of what we are being taught. Only an affirmation can be doubted.
The fact that in order to describe the circumstances in which we learn a language we have to make use of a language which is sufficiently structured in which the process of reference has reached full maturity is doubtless, partially responsible for the natural tendency to believe that the world, apart from every description or conceptualization, is “divided up”, organized into objects, qualities and/or facts, and that the “external” world determines in an univocal manner the linguistic form which adequately describes it. The linguistic philosopher will reject this belief. It is not a matter of affirming that nothing exists before the advent of language in the world. Just as in Kant, it is not denied that there might be things in themselves; but the active participation of the individual —in this case through language— is acknowledged in the constitution of that to which knowledge refers.
Within the linguistic orientation, the most intelligent effort to give form to this concept of scientific knowledge is that of Kuhn. In harmony with the majority of contemporaries Kuhn tells us that in periods of scientific revolution “the way the scientist perceives his surroundings has to be re-learned —in a familiar situation he must learn to identify a new Gestalt. When he has succeeded in doing this, his world of investigation may seem to him in many places incommensurable with the one he inhabited before”.
As is well known, one of the basic senses in which Kuhn uses the term “paradigm” is identical with the sense it has in the expression “argument of the paradigmatic case”. Paradigms or “examples” are apt-instruments for the assignment of meanings through ostensive processes. For Kuhn, one of the essential keys of every learning process consists of this procedure, so difficult to understand but of undeniable practical effectiveness: the ostension. Up to now we have tried to emphasize the patent or hidden similarities behind the various positions defended by contemporary writers. Behind them may be found undeniable differences to which we must briefly refer.
One interesting way to appreciate the radical differences between those positions is to consider their reaction to the kind of scientific change that is sufficiently radical and revolutionary so as to fall outside the category of what Kuhn would call “normal science”.
For Popper and some of his disciples revolutionary change is normally a process in which the original reference is preserved. It is possible for the Popperian to understand the essential part of the process of scientific change as a sequence of theories which only alters its theme to the degree that they extend it. For those who attack the problem of scientific knowledge in the Wittgensteinian tradition, for the Kuhnians, and for the disciples of Popper —on those occasions when they forget their character of being disciples— a sufficiently radical scientific change does not preserve the original reference.
Two sufficiently different scientific theories would function like two classes of statements about an ambiguous “gestaltic picture”, for example, using the Wittgensteinian illustration, the first making statements about the duck and the second about the rabbit. Even though there may be a sense, very difficult to characterize, in which both systems of statements are about the same thing, what the statements of each class refer to, in this sense, does not appear to be the same thing. Therefore the categorial statements do not seem to contradict themselves.
For Sellars, the scientific change must be understood on the basis of the model provided by the Great Change, the change which perhaps nobody will witness but which, with some reservations, Sellars considers the ideal toward which the process of scientific growth should tend: the replacement of the manifest image by the scientific image.
Just as the development of the scientific image has in part consisted of a demonstration that the objects of the manifest image do not exist —in the realm of the scientific image itself the passage from one theory to another sufficiently different should be understood as the discovery that the old theory did not denote, that is, it lacked referential force. I wish to bring these reflections to a close by asking a number of questions concerning a particularly delicate aspect of the image of knowledge given to us by contemporary writers. Does scientific knowledge and the methodology which describes it constitute a species of subjectivistic “universal evaluator” in which the concept of truth as correspondence has no part to play? Does contemporary methodology lead to subjectivism? It must be admitted that in their least fortunate moments Kuhn, Toulmin and many others have encouraged an affirmative answer to this question; however, if one proceeds beyond certain formulations which may be unfortunate and analyses the reasons Kuhn adduces in support of his position, it is not difficult to see that his hostility toward the concept of truth can be eliminated from his system without changing any of its basic ingredients. What Kuhn really wishes to reject is the idea of science as a process which converges toward a final scene, the ‘Truth’.
There is a second reason why contemporary philosophers tend to avoid the idea of truth. When they reject the use of truth-values in relation to theories, they are often inspired by a clear or confused consciousness that the essential components of a theory are not affirmations. They do not wish to contend that there may be no connections at all between such statements and reality. What they do wish to contend is that this connection is different from what the classicist thinks.
But, what is the nature of this connection? This is the urgent question which contemporary writers will have to try and solve, under pain of setting up a new species of subjectivism.