A CLOSER ANALYSIS OF THE CRITERION OF DEMARCATION SHOWS

4. A CLOSER ANALYSIS OF THE CRITERION OF DEMARCATION SHOWS

THAT IT IMPLICITLY CONSISTS OF TWO INDEPENDENT DIMENSIONS OF DEMARCATION.

A closer examination of the criterion of demarcation reveals that one can make a distinction that Popper has not made explicit, but that seems to form the implicit basis of his considerations and that allows us to make a multiple demarcation and thus to say something about the peculiarity of the other non-empirical kinds of

judgements. There are two main characteristics of statements of empirical science: (1) first of all their logical form of refutability and (2) moreover refutability by experience. That is to say, empirical scientific (systems of) statements must not only be refutable in general but refutable empirically in the sense of methodical testability. Therefore the criterion of demarcation has, strictly speaking, two independent dimensions which Popper does not keep apart, thus incurring a risk of confusion. Popper’s criterion of falsifiability is usually referred to as the crite- rion of demarcation of scientific statements, although falsifiability as a logical property does not delimit science from metaphysics. For Popper unites two aspects in the criterion of falsifiability: one logical, the other having to do with highlighting a particular basis of validity, i.e. experience. That is to say, falsi- fiability, on the one hand, deals with the logical structure of statements and the logical relation of classes of statements and, on the other, with methodologically characterized statements of these classes that refer to experience in the sense of

empirical testability. 26 It is, however, extremely important to keep apart both aspects, the logical one and the one that characterises the basis of validity, because these are two different criteria. It is therefore called for that we take a closer look at the demarcatory capacities of the two dimensions:

(1) On the logical form of refutabilty (falsifiability as a logical relation between classes of statements) : Scientific statements – and systems of statements, in particular – are essentially universal statements (universal if-then statements); from them one can deduce certain negative existential statements (existential bans); hence they can conflict with certain statements by virtue of their logical

form. 27 It was exactly this feature that made the criterion of verifiability prob- lematic. Another consequence is the logical ‘asymmetry between verifiability and falsifiability’ 28 that allows us by logical means of the ‘modus tollens’ to draw inferences from particular statements accepted as true to the falsity of a universal statement. 29

This logical relationship between kinds of classes of statements initially has nothing to do with the fact that empirical statements have this feature. It is only in the ensuing examination – which is guided by the interest in scientific state- ments – that the investigation is confined to this subclass of statements, which is

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characterized by this relationship. It is typical of statements in empirical science that they belong to the classes of statements that stand in this logical relationship. If by falsifiability in general we understand this logical relationship, then the

same fact might also be expressed as follows. Falsifiability in general and empirical falsifiability do not coincide. The first characteristic of scientific

statements is therefore that by asserting something they simultaneously exclude something. Hence informativity always entails the possibility of refutability – in

a case where what was excluded by the assertion is for whatever reason admit- ted, the assertion must be rejected. One might call this the logical aspect of falsi- fiability. 30 But this is not an exclusive property of empirical statements alone.

(2) On empirical falsifiability (reference to experience) : Popper demands not only falsifiability in the sense of the mere logical possibility of refutability, but also in the sence of refutability by experience, empirical falsifiability. That is, scientific statements have to be such that they exclude not just any statements, but certain statements about our experience – basic statements – whose truth

would imply the falsity of the respective scientific statement. 31 The aspect of refutability by experience gives the statements empirical informative content and makes them empirically scientific.

Demarcation is thus based on the logical property of refutability – falsifiabil- ity (or non-falsifiability) – in general, on the one hand, and on the particular kind of refutability by experience, the method of empirical testability, on the other. For only the two taken together define the realm of empirical science. 32

Hence what makes any (informative) theoretical system empirically scientific is this reference to our methodical experience. Testability by experience ‘appears as a distinctive method whereby one theoretical system may be distinguished

from another’ 33 Given this positive characterization of empirical scientific (systems of) state-

ments as empirically falsifiable, we might be able to say something about the other systems of statements from which scientific statements are delimited re- spectively by the two dimensions of the criterion of demarcation.

1. The logical property of falsifiability delimits analytic from synthetic judgements. Synthetic judgements – metaphysical as well as empirical – are formally delimited by the common logical property of falsifiability (the logical possibility of being refuted). Therefore, the characteristic of falsifiability (test- ability) has to be regarded as a feature of all informative (synthetic) judgements.

We also find this relationship in the case of metaphysical judgements, as in the case of empirical statements, where negations of metaphysical judgements also define contents that are excluded by them in the case of non-empirically

testable (metaphysical) statements. Thus, for instance, metaphysical determinism (every event has a cause) excludes something (there is no event that has no cause); an uncaused – free – event of volition even though it is not empirically testable, would at least be something that is subject to this ban. That is to say, the

fundamental logical asymmetry between verifiability and falsifiability, between

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logical provability and logical refutability, also exists in the case of – non- analytic – metaphysical statements.

Consequently, falsifiability distinguishes informative judgements from con- tradictions and tautologies and thus determines their synthetic character.

2. In opposition to this sole criterion of demarcation between empirical and metaphysical statements (which are falsifiable as well) is empirical testability (i.e. refutability though the property of being related to experience) which, how- ever, does not coincide with falsifiability as a logical property. 34

The difference between metaphysical and empirical statements is therefore solely due to the methodical difference in the type of empirical and non-empiri- cal testability, it being an open question as to what might be regarded as testabil-

ity in various cases. Since empirical testing is determined by ‘methodology’, there can also be criteria for the testing of metaphysical statements. 35

If content is determined by the degree of falsifiability, then content and empirical content do not coincide, i.e. there are non-empirical but by virtue of their logical form nonetheless falsifiable (synthetic) statements that have to be considered as rich in content even though they are empirically empty.

Thus we have to distinguish between testability and scientific testability. Which criteria of testability would have to be applied for metaphysical as well as for scientific considerations, respectively, is another question.