1. The word ‘ideal’ is used throughout in a somewhat not precise sense, being equivalent in its meaning to ‘non-existing but possible to realize’. Hence, strictly speaking, it is in some contexts superfluous. A different question must be asked: how can there exist sentences which have not been written by anybody and which are studied by the metalogicians? The question may be answered in different ways. We can suppose that the existing sets of elements of the material world contain in themselves any shapes which are defined as expressions of the system investigated. Hence to write a certain expression belonging to the system is tantamount to the repetition of a certain shape which already exists in nature. One can also apply certain theory of possibility. The solution of this problem is not nescesary for our argument.
2. Nevertheless a similar distinction can also be drawn here. For instance, in historical sciences all correct descriptions of objects existing at present and which can be seen by every living man (i.e. documents) may become scientific descriptions. All other sentences about events in the past belong to the realm of theory and are usually individual hypotheses. Apart from these hypotheses, which refer to past events, the historian accepts in a more or less conscious manner various laws of physics, chemistry, biology and psychology which, together with purely historical hypotheses, offer the explanation of the fact that such and such a document can be found nowadays at such and such a place. Or, speaking more precisely, a historian adopts such historical hypothèse, from which, together with general laws, he would be able to deduct the descriptive sentences which refer to the present state of documents. Since a very great number of various assumptions enter into historical theories, their formalization may appear practically impossible and perhaps even purposeless, for reasonings are not so involved that their formalization would result in their simplification.
3. For instance, in the sense of Rudolf Carnap, cf. his ‘Testability and Meaning’, Philosophy of Science 3–4 (1936–37).
4. The concept of a thing of everyday experience is, therefore, relative. It signifies those objects which the said people can see and touch. Of course, the word ‘can’, as it is used here, does not have a clearly defined meaning. Nevertheless, it is difficult to avoid that word in any methodological consideration where we speak constantly about possible forms of science. The word ‘can’, or its various narrow-ings, appear to be typically theoretical and not descriptive. It can only be reduced to certain descriptive operational terms, but cannot itself become descriptive term.
5. The descriptive language in this sense will not be limited to the description of someone’s sensations, but may contain all descriptions of the things of everyday experience, hence also, among others, the descriptions of the experiencing people. On the other hand, by reistic language we mean such a language which can be reduced, in an easily visible fashion, to such a language which is characterized by the following conditions: (1) Among logical types there is the lowest category and all expressions of logical types are functors of the lower ones. (The lowest type can be called the category of the names of objects.) (2) The primitive expressions of language (except quantifiers and truth functions such as implication or negation) are functions in which only the expressions of the lowest logical type are arguments (e.g. the variables of the lowest category). (3) All names of bodies which can be seen or touched, hence the names of animals, plants, objects and so on, or, in general, all names of bodies in the somatic sense, are regarded as constant names belonging to the lowest logical type. (If only the names of bodies are constant names of the lowest type, then such a language can be called somatistic.)(4) The names of psychological experiences do not belong to the lowest logical type, but to higher types. Sensations, notions and ideas are not objects, but rather they constitute a way of psychological experience. (For instance, if I want to describe that A imagines a mount of gold, we say that A imagines in such a way in which he would experience remembering such a mount of gold, had he seen it previously), cf. T. Kotarbiński:’ sur l’attitude réiste (ou concrétiste)’, Synthese VU (1948/49).