Last time we examined Laudan's criticisms of the hierarchical model of scientific justification. As you recall, his point was not that scientific debate is never resolved as the hierarchical model would predict; it is just that it does not always do so. Laudan thinks that the hierarchical model is often plausible, so long as it is loosened up a bit. In particular, the hierarchical model has to allow that not all disputes can be resolved by moving up to a higher level; also, as I mentioned at the end of the last session, it has to allow for elements from a lower level to affect what goes on at a higher level. (For example, it was mentioned that the methodological rule that double-blind tests be preferred to single-blind tests was based on the factual discovery that researchers sometimes unintentionally cause patients who have received a medication, but don't know whether they have, to be more optimistic about their prospects for recovery and thereby affect how quickly people recover from an illness.) If these adjustments are made, the hierarchical model becomes less and less "hierarchical."
In the end, however, the what makes the hierarchical view essentially "hierarchical" is that there is a "top" level (the axiological) for which no higher authority is possible. To put it less abstractly, a theory of scientific justification is hierarchical if it says that there is no way to adjudicate between disputes at the (axiological) level of cognitive values, aims, or goals; disagreement at this level is always rationally irresolvable.
Laudan wants to dispute the claim that disagreement at the axiological level is always irresolvable. Instead, he argues that there are several mechanisms that can and are used to resolve disagreements at the axiological level. To see that these mechanisms exist, however, we have to drop all vestiges of the view that scientific justification is "top-down." Instead, scientific justification is a matter of coherence between the various levels; scientific disputes can be rationally resolved so long as one or more of the levels is held fixed.
Central to this model of scientific justification is the view that the different levels constrain each other, so that holding some of the levels fixed, there are limits to how far you can go is modifying the other level(s). This means that it must be possible for some of the levels to change without there being change at all the other levels. Before Laudan describes this model, which he the "reticulated" model of scientific justification, in detail, he first discusses a common but flawed pattern of reasoning that leads many people to think that there must be "covariation" between all three levels.
The Covariation Fallacy
If these theses are correct, then theoretical disagreements between scientists would indeed have to be accompanied by disagreements over aims, e.g., what counts as an acceptable scientific explanation. Laudan, relying on the fact that there is underdetermination between every level, argues that this is not necessarily so. People can agree over what counts as a good scientific explanation while differing over whether a specific theory meets whatever criteria are necessary for a good scientific explanation, or over what methods would best help promote the acquisition of good scientific explanations. (Kuhn's view, of course, is that there must be a difference at the higher level if disagreement occurs at the lower level; thus, he argues that the scientists agree only at a shallow level--theories ought to be "explanatory"--while disagreeing about what those criteria specifically amount to.) What is perhaps more important, people can disagree about the aims of their discipline (e.g., truth vs. empirical adequacy, or consistency with the evidence vs. conceptual elegance, simplicity, and beauty) while agreeing about methodology and theory. (TEST: Get a group of scientists who agree on theory and method and then ask them what the ultimate aims of their discipline are; you might find surprising differences.) This would occur if the methods in question would promote both sets of aims. Similarly, the same theory can be deemed preferable by two different and deeply conflicting methodologies. That is, a theory can win out if it looks superior no matter what perspective you take. This is how things have often occurred in the history of science, according to Laudan.
Kuhn commits the covariance fallacy, Laudan argues, in his arguments for the view that theory, methods, and values, which together make up a paradigm, form an inseparable whole. As Laudan construes him, Kuhn thinks that a paradigm is a package deal: you can't modify the theory without affecting the methodological rules, or how the aims of that discipline are conceived. On the contrary, Laudan argues, change can occur piecemeal, one or more level at a time (with adjustments to the other levels coming later).
How Can Goals Be Rationally Evaluated?
Laudan describes two mechanisms that can be used to adjudicate between axiological disputes: (1) you can show that, if our best theories are true, the goals could not be realized (the goal is "utopian"); and (2) the explicitly espoused goals of a discipline are not (or even cannot be) reflected in the actual practice of that discipline (as evinced in its methods). Mechanism (1) tries to show a lack of fit between theories and aims, keeping the former fixed; mechanism (2) tries to show a lack of fit between methods and aims, keeping the former fixed.
Method (1) - Different Kinds of "Utopian" Strategies:
(a) Demonstrable utopianism (goals demonstrably cannot be achieved, e.g., absolute proof of general theories by finite observational evidence);
(b) Semantic utopianism (goals are so vaguely that it is unclear what would count as achieving them, e.g., beauty or elegance);
(c) Epistemic utopianism (it's impossible to provide a criterion that would enable us to determine if we've reached our goal, e.g., truth).
Method (2) - Reconciling Aims and Practice
(a) Actual theories, methods cannot achieve those aims. Examples: Theories must be capable of proof by Baconian induction from the observable evidence; Explanatory theories must not speculate about unobservables. Both were rejected because the practice of science necessitated the postulation of unobservables; so Baconian induction was rejected as an ideal and replaced with the Method of Hypotheses (hypothetical-deductivism). Here agreement over theories and methods--which didn't make sense if the explicitly espoused aims were really the aims of science--provided the rational basis for adjusting the explicitly espoused aims of science.
(b) All attempts at achieving those aims have failed (e.g., certainty, explanatory, predictive theory that appeals only to kinematic properties of matter).
Three Important Things to Note about Laudan's Reticulated Theory of Scientific Rationality: on Laudan's view, (1) because the levels constrain but do not determine the other levels, it is sometimes the case that disagreements over aims are rationally irresolvable--but this is not generally the case; (2) the levels are to a large degree independent of one another, allowing for paradigm change to be piecemeal or gradual rather than a sudden "conversion" or "Gestalt shift;" and (3) scientific "progress" can only be judged relative to a particular set of goals. Thus, Laudan's view, like Kuhn's, is relativistic.
(Important: Like Kuhn, Laudan denies the radical relativistic view that progress does not exist in science; he simply thinks that whether progress occurs in science can only be judged relative to certain shared goals, just like whether certain aims are reasonable can only be judged if either theory or method is held fixed. Judgments that progress has occurred in science, relative to fixed goals, can therefore be rationally assessed as true or false.)