Given the high marks assigned to Toulmin for his commentary on Kuhn and the affinity of his program with that of Popper (evolutionary epistemology vs formalism) , what does he say about Popper? The short answer is that he dismissed Popper as one of the formalists.
Does this mean that there is a problem with Popperian exegesis rather than with the contents of Popper’s ideas. How did Toulmin read Popper and only see a positivist who used falsification rather than verification as his lodestone?
Popper’s Objective Knowledge should have indicated the overlap of their evolutionary programs but that book came out in the same year as Toulmin’s Human Understanding so he would not have read it in time but there were plenty of signs that Popper was heading that way before the collection appeared in one volume.
At a conference on the state of British philosophy at the mid-century Popper wrote that he was more concerned with serious problem-solving rather than paying attention to what the other philosophers were up to but maybe he could have been more alert to the damage that could be done when massive numbers of students flooded into the universities in the postwar expansion and started to take on all the fads and fashions of the time. Jarvie suggested in his Rethinking Popper paper (conference 2007, proceedings published 2009) that Popper maybe should have been more active in networking and empire-building.
Turning to Toulmin on Popper. In the Conclusion there are several critical references to Popper. Before commenting on these, recall where Toulmin is coming from: his project is to establish or re-establish a relationship between philosophy and science (both theory and practice) which he considered did not exist at the time due to the obsession of the philosophers with logical proof or some similar form of justification of beliefs. He advocated an evolutionary or ecological approach to the community of scientists and their ideas as they exist at the time. [He wrote “Sir Karl Popper’s capsule description of scientific method as a dialectical succession of ‘conjectures’ and ‘refutations’ can at once be reinterpreted in evolutionary terms: it lays down the ecological conditions on which alone variation and selection can lead to effective scientific change.” P. 140, my italics.]
Toulmin’s wanted to formulate a revised concept of rationality which is not a property of ideas or people but instead it is a matter of the attitude which people adopt towards contending ideas and the way they form critical preferences and if necessary revise them in response to changing circumstances. (He did not use the term ‘critical preferences’)
All of that suggests that Toulmin was not just working in the same vineyard with Popper but also producing a very similar kind of wine! However he was more concerned with his differences with Popper than the similarity which he identified at page 140 (above). This of course is appropriate if the differences are real.
He started the Conclusion by taking aim at the idea that the acceptability (rationality) of scientific theories depends on their “comparative logicality”. He suggested that some people (naming Popper, Lakatos and Kuhn) were trying to “extend the notion of rationality beyond the scope of formal logic and to find some way of reapplying it in situations involving conceptual change” (479). He thought that this was misleading if it was interpreted as a move in the right direction because fundamentally he himself was moving in the opposite direction. “Popper and his associated have all taken the formal logician’s approach as a starting point [and] conceptual change has continued to be more or less of an anomaly for them [and they are] extending an analysis of ‘rationality’ which is still primarily formal.” (479)
His own concept of rationality is not based on formal entailments, inductive logic or the probability calculus because his ecological approach allows him to approach the central problems of decision-making in a community with “no appeal (such as Popper makes) to an arbitrary, a priori demarcation criterion as the definition of science.” (480).
He saw Popper as being concerned with problems of formal proof or refutation and he regarded ‘falsifiability’ as Popper’s alternative to ‘verifiability’ as “the universal, timeless lest of a genuinely scientific hypothesis”. Even when Popper softened his position to allow corroboration as well as refutation, still his concern was “the acceptability of propositions rather than the applicability of concepts; while his approved procedures of rational investigation – i.e. scientific testing, refutation, and/or corroboration – have continued to be variants on those of earlier propositional logicians.” (480-81)
Toulmin insisted that Popper never shifted from his dedication to “a set of general a priori conditions, which have been imposed on all scientific reasoning from outside, by his own – ultimately arbitrary – definition of what is to count as a ‘scientific’ hypothesis, theory or concept” (481) He suggested that Lakatos might advance beyond Popper by paying more attention to the historical record but still there was the problem of interpreting the historical record.
Turning to explore the “empirical basis” for Toulmin’s criticism of Popper, the search should cease a year or two before 1972 when Human Understanding was in press and it was to late to incorporate new material from Popper’s published work such as the collection Objective Knowledge.
What can we make of the claim that Popper used falsifiability as an arbitrary, a priori definition of science and the functional equivalent of verifiability in the program of the logical positivists and logical empiricists? To the contrary, it would seem that Popper’s approach to falsification was very much like Toulmin’s requirement that ideas should be worked out in the context of the scientific situation at the time in a particular scientific community.
Popper described his adoption of the criterion as a response to the situation in Vienna when Marxists, Freudians and followers of Adler all claimed that their systems were scientific and all-embracing in their explanatory power. In contrast, Einstein was prepared to formulate his theory in a way that permitted observational or experimental tests, with the risk of refutation. Popper saw a fundamental difference between the two kinds of theories, each of which was supposed to be scientific and he decided that the capacity for falsification was a very desirable characteristic for a system which claimed to be a science.
That means that Popper’s falsifiability criterion was not really a definition of science (he was not into definitions!) but a proposal to adopt a critical attitude towards theories and especially to check whether they were open to empirical testing. It was a proposal or a convention and its merit was to be judged by its helpfulness in coming to grips with problems in the theory of knowledge (and the practice of scientist). As for being timeless and a priori, Popper noted that there are degrees of testability (so the line of demarcation is not sharp) and the testability of particular theories will change with progress in theory and experimental technology.
Turning to the philosophy of science the aim was verification or inductive probability and the inductive method was regarded as the hallmark or criterion of science. Popper saw that there were intractable logical problems with verification and also induction. He might have been satisfied with his useful job as a schoolteacher (he wrote an amusing paper in All Life is Problem Solving to explain how he became a philosopher by accident) but as a good government worker (“I am from the government and I am here to help”) he probably wanted to help the positivists so he made up a lot of arguments that might have changed their minds and the direction of their work. In the event he did not succeed, beyond persuading Carnap to adopt testability as the criterion of meaning which probably did more harm than good by promoting the appearance that Popper was really one of them.
The same perception was no doubt reinforced by Popper’s persistent engagement with the positivists and their successors on the logic of demarcation and induction. Jarvie suggested that his ongoing debate on those topics distracted people from picking up the social or institutional turn which was present in The Logic of Scientific Discovery, albeit in a muted form. Popper’s close engagement with the logic of demarcation and induction may be misled Toulmin who missed the point that it is ok to focus on logic when logical issues are at stake, which was all the time for the logical empiricists. But Popper was playing a much bigger game and for all his demands that scientific systems should be testable it was quite clear that much more was required for a good theory. Testability was a minimum requirement, like a steering wheel for a car, but no salesman would list the steering wheel among the selling points! The theory had to have explanatory power, it had to be consistent with other well tested theories, and so on.
Rounding off this note before it gets too long, I really want to find out what Toulmin through about Popper’s objective knowledge and the evolutionary approach when Popper’s collection appeared. More research required!
