The book exposes serious flaws in the reductionist assumptions of Mind and Matter of Naturalism and Constructivism, which underlie research and theorizing on cognition, language and action within current academic psychology. The author argued for alternative tenable assumptions about the relation between mental and material reality which, as a matter of principle, must be taken for granted, and be the point of departure for all further investigations into both reality and our descriptions of it. It is the intention to show that the assumptions and principles derived from the arguments in the book offer a consistent foundation for a science of psychology. Furthermore, it seems that they open up new and straightforward ways of dealing with key-issues of truth and intentionality, subjectivity and objectivity, of relevance to psychology, philosophy and the humanities.
PSYCOLOQUY CALL FOR BOOK REVIEWERS: Below is the Precis of "Principles of Cognition, Language and Action: Essays on the Foundations of a Science of Psychology" by Nini Praetorius (720 lines). This book has been selected for multiple review in Psycoloquy. If you wish to submit a formal book review please write to firstname.lastname@example.org indicating what expertise you would bring to bear on reviewing the book if you were selected to review it.
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The project of my book can best be summarized as an attempt to find out whether in psychology a basis of commonly agreed assumptions, concepts and principles may be found on which to base scientific investigation and theorising on that which uniquely characterises the subject matter and phenomena falling within the subject area of psychology, namely the cognizing, feeling, acting, self-reflective and language using person. The situation in academic psychology to-day is that a plethora of radically different theories, models and conceptual schemes has been developed and adopted, often resting on incompatible assumptions about the psychological phenomena and functions being investigated. In order to pin point the reasons for this state of psychology, I have tried to unravel the assumptions behind some of these models and theories, and to trace their scientific and philosophical origin.
During this work I have identified alternative assumptions and presuppositions, primarily about the relation between the cognition, perception, action and use of language of persons and the material and social reality that this cognition, perception, action and use of language concern, which I think we have to take for granted, and which necessarily must form the point of departure for any further investigations into the psychological functioning of persons. It is my contention that these assumptions, among them the assumptions about subjectivity and objectivity, truth, identity, and inter-subjectivity, form a matrix of interrelated assumptions, the consequences of which cannot be dealt with consistently if conceived of separately or in isolation.
My rationale for soliciting commentary on these and other issues raised in my book is, first, to get independent assessment of the tenability of the assumptions I have identified, and of my arguments for their necessity. Secondly, despite the modest results so far, it would be beneficial for me to have the opinion of colleagues as to the strengths - and weaknesses - of my approach to help provide a foundation of assumptions for a science of psychology.
1. During the last couple of decades a growing concern has been expressed as to why psychology, now more than a hundred years after becoming an independent research area, does not yet meet the basic requirements of a scientific discipline on a par with other sciences such as physics and biology.  These requirements include: agreement on the definition and delimitation of the range of features and properties of the phenomena or subject matter to be investigated; secondly, development of concepts and methods which unambiguously specify the phenomena and the systematic investigation of their features and properties. A third equally important requirement, implicit in the first two, is exclusion from enquiry of all other matter with which the discipline is not concerned. To these requirements must then be added the development of basic assumptions about the nature of what is under investigation, and of principles to account for its properties and to serve as a guide to relevant questions to ask and theories to develop.
2. One of the major obstacles for psychology in establishing itself as an independent scientific discipline has been that of delimiting its subject area from those of other sciences, in particular physics and biology. This is understandable, since human beings have bodies made up of physical matter, which, like all other matter, obeys the laws and principles of physics, and to this extent may be described and accounted for in terms of physics. Likewise, human beings are living organisms like other living organisms, built up of cells and organs, which, in order to stay alive and procreate, organise their interaction with the surrounding environment in ways which serve biological ends. Whether for these or for other reasons, it has apparently been difficult to reach agreement on the PSYCHOLOGICAL properties that uniquely characterise human beings as opposed to mere physical systems and biological organisms, and thus to agree on what properties and features human beings have apart from or in addition to those of physical systems and biological organisms. Admittedly, most psychologists to-day can agree that human beings are persons who may act, cognize, think and feel, and who develop languages in which together they may reflect on and communicate about their actions and what they cognize, think and feel. Likewise, most psychologists would agree that such psychological phenomena fall within or even define the area of psychological inquiry. However, when it comes to assumptions about the nature of these psychological phenomena and properties of persons, or the concepts, models and principles by which they may be adequately described, there is little common agreement among psychologists. Even worse, discussion about issues as fundamental as these, which has proved to be essential for the development and progress of the natural sciences, is almost totally lacking within psychology. Lacking also is debate as to whether the wide variety of (often incompatible) models and conceptual systems, currently used to describe psychological phenomena, are indeed adequate, just as is reflection about the tenability of the assumptions on which current conceptual schemes and models are based.
3. The book aims to alert psychologists to the importance of such debate and reflection, and in particular to serious flaws in the assumptions of traditional and more recent philosophical positions and theories about cognition, perception, language and action, by which current academic psychology is influenced. To this end a critical discussion addresses, on the one hand, the assumptions of the NATURALIST positions , which dominate research and theorizing within traditional, so called "experimental" psychology on perception, cognition, language and action, and on the other, the radically contrasting assumptions of the CONSTRUCTIVIST positions  which dominate the so called "social constructionist movement" and its research and theorizing about the same issues. It is the aim of this discussion to show that by the adoption in psychology of these philosophical positions, the flaws they inherit and problems to which they give rise, cease to be of merely "philosophical" interest, but become flaws and problems within the foundations of academic psychology itself.
4. The assumptions of the philosophical positions of Naturalism and Constructionism - just like their Classical Materialist and Idealist forerunners - represent attempts to solve the problems about the relation between Mind and Body and Mind and Reality, which arose some 400 years ago as a consequence of the Cartesian division of reality into two fundamentally different and independently determinable parts or "realms". For its part, this division, known as Mind-Matter dualism, was Descartes' attempt to solve the problems which arose at a time when it seemed that a mathematical, quantitative description of the world was sufficient to describe the behaviour of objects in material reality. Thus, knowledge of an object's geometrical form, motion, mass and solidity was all that was necessary to account for its motion relative to other objects. It was natural to suppose, therefore, that these properties were the only ones that objects "really" possessed, and that the other characteristics of objects, e.g. their colour, smell, warmth, coldness, taste and other non-quantifiable properties of objects, were only apparent - and in some way or other dependent on ourselves. Such properties or phenomena, as Galileo put it, were merely "names residing solely in the sensitive body" (Galileo, 1953). It had to be admitted, however, that in a number of respects our bodies are also entities and mechanisms resembling lifeless, material objects - but if we ourselves are a kind of mechanism, how then could any event not describable in physical terms take place in us?
5. Descartes "solved" these problems by modernising the Christian concept of the Soul, making it a "realm" for all the faculties, qualities, and phenomena for which there was no longer room in the mechanistic world-view. The soul became the domain to which experiences, sensing, beliefs, feeling, free-will and thought belonged (Descartes (1637/1967). However, with this division of reality into a "physical" and a "mental" part, arose a number of puzzling and intractable problems, which have kept philosophers busy ever since. There was first the problems of how a reconciliation could come about between the "material" and the "mental" - if indeed there could (i.e. the psychophysical problem about the relation between Mind and Body). And, secondly, there was the problem, partly epistemological and partly ontological, namely if the ideas and perceptions of objects residing in our minds to which we have immediate access, are the only phenomena the existence of which we can be certain, then what guarantee do we have that those ideas are TRUE, or that the objects perceived are MATERIAL? (i.e. the problem about the existence of material reality). And there was the problem, thirdly, that if any one of us only has direct access to the thoughts, feelings and cognition our own minds, then how can we be certain that the thoughts, feelings and cognition of other persons are the same as those we ourselves entertain? Indeed, how can we be certain that the world itself, including other people and their minds, exists as other than ideas in our own private minds? (i.e. the problem of the privacy of our minds).
6. Present-day Naturalism and Constructivism share the assumption with classical Materialism and Idealism that the Mind-Matter problems may actually be solved - and that the way to do so is by denying the independent existence of either one or the other "realm" - in effect, by reducing the one to the other. Within Naturalism (as within Classical Materialism) attempts have been made to solve these problems by proposing that mental states, in virtue of having physical causes and effects, must themselves be something physical, and hence in some way or other must be reducible to or deducible from physical or biological states and processes of the body, and its causal interaction with physical reality (4). Conversely, within Constructivism (as within Classical Idealism) attempts have been made proposing that the world of matter is nothing but a product of conceptual and linguistic schemes which somehow or other are "fabricated" or "invented" by our minds, and thus is reducible to something mental.
7. However, far from solving the Mind-Matter problem and the range of related epistemological problems arising from the Cartesian division of reality into a physical and a mental part, each with its own independently determinable existence, the reduction of the physical to mental phenomena by Constructivism, and vice versa by Naturalism, have only made these problems even more intractable - and added a few more to the original list. What has not always been realized is: Despite the apparently completely opposed assumptions of Constructivism and Naturalism, most of the problems to which they lead are exactly the same, among them problems of inconsistencies in the notions of objectivity and subjectivity, truth and inter-subjectivity and therefore, inevitably, inconsistencies in all other key epistemological notions. Further discussions in the book should make this clear .
8. Others have argued that the assumptions of Naturalism and Constructivism about the relation between Mind and Matter are untenable, and that their reductionist solutions of the problems to which these assumptions give rise have nonsensical consequences. Some philosophers have long since realized that these problems cannot be solved , just as it has been argued that the "Cartesian Mind-Matter myth" and the problems it involves needs to be "dissipated" rather than solved (Ryle, 1949). What is new in the book is the argument that REASONS OF PRINCIPLE exist why Cartesian Mind-Matter dualism, and the host of derived epistemological and ontological problems to which it gives rise, entail assumptions about the relations between Mind and Matter, WHICH PREVENT THESE PROBLEMS FROM BEING CONSISTENTLY STATED and, therefore, FROM BEING SOLVED - be it by the natural sciences or by empirical psychological research or, indeed, by philosophical investigations. More importantly, though, it is shown that the arguments refuting the Naturalist and Constructivist assumptions and solutions of the Mind-Matter problems, suggest and point to tenable ALTERNATIVE assumptions about the relation between Mind and Body and Mind and Reality, which not only have to be taken for granted by epistemology, but which must necessarily be fundamental for the development of consistent and coherent theories and research in psychology about the cognition, language and action of persons.
9. Arguments in refutation of the assumptions behind the Mind- Matter problems and their proposed solutions are not particularly complicated, nor are the arguments for the alternative assumptions by which they must be replaced. The main line of a GENERAL argument presented in the book against these problems of Cartesian dualism is that they imply the following conflicting assumptions. On the one hand, the possibility of a polar opposition between Mind and Matter is assumed, which necessarily implies AND requires that we may indeed talk consistently and correctly about BOTH Mind and Matter; and, on the other, it is assumed that Mind and Matter are INDEPENDENTLY DETERMINABLE "realms" in the sense that the content of each realm may be talked about and characterized independently of referring to the content of the other. That these assumptions are conflicting becomes obvious when we consider the impossibility of talking consistently about what exists in material reality, independently of assuming that material reality exist as something we may perceive, have knowledge of, and about which we may put forward propositions which are true, and thus without referring to our perception, cognition and description of it. Consider, conversely, the impossibility of assuming that we can talk consistently about our perception, knowledge and descriptions of reality, without referring to reality and these things; i.e. the impossibility of talking about WHAT we perceive, cognise and describe, without at the same time taking about and referring to THAT which we perceive, cognise and describe.
10. To take a concrete example. How can we possibly talk consistently about the apples on the table "out there", without presupposing that such things as apples and tables "out there" exist as things that we may indeed perceive, have knowledge of and put forward true propositions about, and therefore independently of referring to our perception, cognition and description of them. And conversely, how can we possibly talk consistently about the content of our perception, cognition and description of the apples on the table "out there" without or independently of referring to, and talking about, the actual apples on the table in question? Without presupposing these interdependencies, neither talk about actual apples on the table "out there", nor of perception, cognition or descriptions of them would make any sense.
11. Thus, rather than assuming that Mind and Matter are independently determinable "realms", it would seem that the very possibility of describing and characterizing both Mind and Matter consistently presupposes the assumption of an INTERDEPENDENCY between Mind and Matter, i.e. between our perception, cognition and description of material reality, and the material reality which exists independently of our perception, cognition and description of it. Indeed, for the sake of epistemological consistency we shall have to presuppose that a NECESSARY RELATION exists between our cognition, perception and description of reality and reality being perceived, cognized and described, that is, presuppose that we may perceive, have knowledge of and also a language in which we may put forward propositions about reality which are true. Without presupposing so, we would quite simply not know what we were talking about when we talk about REALITY and things in reality, let alone about our COGNITION, PERCEPTION and DESCRIPTIONS of reality and things in reality, which may be true or false.
12. This is an assumption that must be taken for granted as a matter of principle and be the point of departure for all our further investigations into both reality and our perception, cognition and description of it - be it in ordinary everyday or in scientific situations. This assumption is formulated as a principle called THE PRINCIPLE OF THE GENERAL CORRECTNESS OF LANGUAGE AND KNOWLEDGE, or just, the Correctness Principle. It is a principle which implies that to be a person and a language-user is to have knowledge about reality, oneself, and the situations in which one finds oneself in reality, and a language in which one may put forward propositions which are true - or false - about reality, oneself and these situations. To anticipate an obvious objection, let it be stressed that the Correctness Principle does not mean that all or every proposition put forward in language about reality and our cognition and perception of it are true or correct - on the contrary, they may be false or incorrect. Indeed, we may very often discover and determine that they are. However, no determination of the truth of any PARTICULAR proposition about reality or of our cognition and perception of it could be carried out, let alone would make sense, without presupposing that, GENERALLY, the language in which the determination is conducted may be used to say something with is correct, true or false, about that which we talk, and thus is a language to which the Correctness Principle applies.
13. For the same reason it is a principle the validity of which cannot be proved. It can only be shown that if we do try to prove it - or, worse, try to doubt or deny it - we will involve ourselves in circularities, contradictions or absurdities. However, it is sufficient to show that attempts to prove the principle would have to presuppose the principle, and that, conversely, attempts to doubt or deny the principle would amount to assuming that we may use language to doubt or deny that we can say anything about anything, which is true.
14. Following an analysis of the further consequences of the Correctness Principle it becomes clear that a LOGICAL RELATION exists between key-notions used to characterize, on the one hand, our cognition and description of reality and, on the other, reality, i.e. notions such as 'knowledge', 'propositions', 'reference', 'true', and 'reality' and 'things' or 'facts of reality'. This relationship is to be understood as logical in the sense that none of these notions has well defined meanings independently of reference to the others, nor may any of them be reduced to or deduced from any of the others. For this reason alone, it will be equally impossible to reduce that to which any of these notions refer, to that which any of the others refer, and thus to reduce Mind to Matter - or vice versa.
15. To this point may be added that referentiality and truth are logical properties of knowledge and linguistic propositions, but not of physical, physiological or biological states or processes - by any definition of physics, physiology or biology. It may be true or false that physical, physiological and biological states and processes exist, but such states and processes cannot themselves be TRUE or FALSE, nor be ABOUT anything IN THE SENSE THAT KNOWLEDGE AND DESCRIPTIONS MAY BE. Neither is there any way in which these logical properties of knowledge and propositions - referentiality and truth - may be reduced to or explained in any of the terms we use to account for physical, physiological or biological states or processes. Indeed, REASONS OF PRINCIPLE exist why referentiality and truth, which cognition and language share with logic, cannot be reduced to nor be explained in terms of processes and states, which are more fundamental than referentiality and truth. Among these reasons is the impossibility of accounting for these more fundamental processes and states without describing them, and thus without implying the existence of referentiality and truth. To assume otherwise would be just as absurd as assuming that logic and its principles, on which par excellence the language of science relies, could be reduced to or explained in terms of something more fundamental or elementary without using logic
16. From these arguments it follow that, on the one hand, the very possibility of an ontological distinction between Mind and Matter precludes EPISTEMOLOGICAL MIND-REALITY DUALISM, i.e. the assumption that Mind and Matter are independently determinable entities or realms. And it follows, on the other hand, that the epistemological conditions for distinguishing between and talking in well defined ways about Mind and Matter, at the same time necessitates the assumption of ONTOLOGICAL MIND-BODY DUALISM, which precludes reductionism. In other words, precludes psychological states and properties of Mind, which uniquely distinguishes Mind from Matter, from being reduced to, derived from, or explained in terms of Matter - and vice versa.
17. Central to these arguments and assumptions is that epistemological and ontological issues and concepts are inter-related. Thus, any consistent ontological determination and distinction between Mind and Matter involves EPISTEMOLOGICAL COMMITMENTS, i.e. presupposes the assumption of a necessary relation between Mind and Reality (or between our perception, cognition and description of reality, and the reality perceived, cognized and described). Conversely, any consistent epistemological account of either Mind or Matter involves ONTOLOGICAL COMMITMENTS, i.e. presupposes the assumption of logical properties of Mind which makes Mind fundamentally and irreducibly different from Matter.
18. It is the contention of the book that the assumptions of THE PRINCIPLE OF THE GENERAL CORRECTNESS OF COGNITION AND LANGUAGE (cf. paragraphs 12 and 13) are assumptions which have to be taken for granted, and on which any further inquiries into the cognition and use of language of persons must be based. In the book a thorough analysis is made of the consequences of this principle for the kind of questions we can meaningfully ask and hope to answer - scientifically and empirically, philosophically and theoretically - about the relation between our perception, cognition and description of reality and reality itself. Following this analysis, a critical discussion is carried out of traditional psychological theories of perception as well as recent philosophical theories of cognition and language. Whilst such theories, as well as any empirical research set to support them, necessarily have to assume the principle of the general correctness of perception, knowledge and language, this principle is either ignored or denied - or both. Consequently, the attempts by these theories to explain how perception and knowledge of the world comes about, and how language and use of language is acquired, proceed in on of two ways. Either they set out to explain what has to be presupposed in order to formulate the theories and to carry out the supporting empirical research - and thus become circular theories - or, even worse, become theories which, in the process of explaining perception, cognition and language in terms of something more "fundamental" or "elementary", deny or "reduce away" the defining properties of perception, knowledge and language - thereby in effect doing away with the phenomena they set out to explain - and with it, of course, the very presuppositions on which the formulation of the theories relies.
19. During extensive discussions of the epistemological assumptions of various forms of the Constructivist and the Naturalist positions it becomes clear that in both positions important key epistemological concepts, in particular the concepts of 'truth' and 'identity', are left ill defined and suffering from inconsistencies. That quite similar inconsistencies and problems occur in these concepts is not surprising, since they may be traced back to inconsistencies in the common assumption of a Mind-Reality dualism on which both positions rest. Indeed, for the very same reason, similar problems and inconsistencies may be found in traditional and more recent Realist, Rationalist and Irrealist theories of Language and Cognition, and their attempts to account for and give arguments in support of the existence of a relation (or lack thereof) between language, cognition and reality. However, taking the Correctness Principle as the point of departure in an analysis of how people may acquire knowledge of and together develop languages to describe things in reality, reveals assumptions concerning the concepts of 'truth' and 'identity' which avoid the inconsistencies.
20. Turning first to the concepts of 'truth' it is argued that the necessity of assuming a logical relation between notions such as 'statements', 'facts' and 'true' (cf. paragraph 14) means that we cannot ask, nor explain or justify how it comes about that we know true statements, i.e. know that true statements are true. In effect, we cannot ask, nor explain or justify how it is that we know correct uses of the word 'true'. On the contrary, notions such as 'true' and 'correct' have to be "primitives" of any theory of language and cognition (as they are in logic and mathematics), which we have to know correct uses of in order to talk about language and cognition and what language and cognition are about, i.e. reality and its facts. If we could not or doubted that we could use 'true' or 'correct' in a correct way, we would quite simply be cut off from using language for talking about anything. If, for example, we say, "it is true that an apple is on the table, but there is no apple on the table", we would immediately know that the word "true" was used in an incorrect way. However, that we and even a child - maybe even philosophers - do know this suffices, indeed it has to suffice. For, there are no other, let alone non-question begging ways of explaining how we know correct uses of "true" and 'correct'. 
21. Another assumptions about the notion of "truth" which has to be taken for granted is the assumption about the inter-subjectivity of the notion of truth. This is the assumption that what is true or false for a person about the things he or she cognizes and describes would also be true for others - could they cognize and describe what the person cognizes and describes. Hence, it is not because persons together may come to agree and make conventions about what is true and false about the things they cognize and describe that they may have or come to acquire a notion of truth. On the contrary, without a notion of truth of which it is presupposed that what is true for oneself is also true for others they could not begin to agree and make conventions about anything. In other words, the notion of truth both implies and presupposes a notion of 'other persons' or just 'others'. This assumption is fundamental for cognition, use of language and communication of persons, and indispensable for any meaningful discussion among persons about what they know, and how they describe what they know. Furthermore, it is a condition on which rests the possibility of persons to distinguish between knowledge and description of what is and what is not publicly observable, and on which rests our determination and characterization of individual differences and variations in our knowledge and description of both that which is publicly observable and that which is personal.
22. Why this is so may become clear when we consider that the very procedures by which we determine what in a situation is materially and publicly observable, presupposes that something is the case or true about the situation and things being determined and observed - which is also the case or true to other people - in casu the people involved in the observations. Thus, it is not because situations exist or may be arranged, in which things are publicly observable, and which we may come to agree to describe in particular ways, that a notion arises of what - for everyone involved - is true or correct about things and situations. It is the other way round, for no such determinations of correctness of knowledge and description of things and situations could be agreed upon, let alone be arranged and function as criteria or standards for correctness among language-users, unless it was presupposed that WHEN arranging and determining these criteria or standards, we already have a concept of 'truth' which is such that what is true or false, correct or incorrect, is also true or false, correct or incorrect for others. It is because of this logical implication of 'others' in the notions of 'true' and 'correct' that we may talk correctly and rigorously about our knowledge of what is publicly observable - and distinguish it from what is not.
23. Thus, the point so easily overlooked is that even in a situation in which the things and events being described are publicly observable, it is logically implied and presupposed by descriptions put forward and understood by others that these others, being in the same situation in which we are, will have the knowledge we have about these things and events, and will use language to describe them as we do. That is, it is presupposed that our notion of 'true' or 'correct' is such that what is true or correct, is also true or correct for 'others'. However, the assumption that situations or points of view in this sense are IN PRINCIPLE SHAREABLE is just as much a condition for determining and characterising individual differences and variation in our knowledge and descriptions, both of that which is publicly observable and that which is personal. The argument of why this is so takes as its point of departure the fact that, despite such differences in knowledge and description of either things in reality or of ourselves and other persons - due, for example, to differences in our background, education, history of experience, culture, and so forth - we are generally able to communicate to others what we know, and even to determine that and how our knowledge and descriptions may differ. This relies no doubt on the fact that, apart from differences in our knowledge, experience and background, we do share a substantial amount of knowledge and description of the world in which we live and act, of the things with which we may act, of ourselves and other persons with whom we may co-act. However, this does not of course suffice to account for the inter-subjectivity of knowledge and description that we do NOT share with others, and which is PERSONAL. It would not do so - unless it is also assumed that, although other people may not be in our situations, and may not have, or may not have had, exactly the same experiences and knowledge that we have or have had, they would - COULD they be, or had they been, in our situations. And assumed, furthermore, that to be a language-user and to share a language with other persons logically implies and presupposes that other language-users - granted they could be in our situation and have the experience, knowledge, background, points of view etc. that we have - would use language to describe what we experience, know of, etc., in those situations as we do. That is, they would agree that the descriptions we put forward about these things and this knowledge are correct and correctly applied.
24. Thus, the inter-subjectivity of cognition, language and communication of persons relies on a notion of 'truth' which logically implies that what is true or false, correct or incorrect, is also true or false, correct or incorrect for 'others'. On this assumption relies the possibility of persons to talk about and determine individual differences in their knowledge and description of things in reality - and whatever else they may have knowledge about or experience - and thus the very possibility of a person to BE a person i.e. someone who is different from other persons. Conversely, the assumption about the logical relation between the notion of 'truth' and the notion 'others' precludes and makes meaningless any notion of 'private minds' and 'private languages' of persons - just as it precludes and makes meaningless the notion that someone with the mind of a "zombie" could ever acquire or share with others a language to talk about anything, (PACE the recent philosophical discussions on Consciousness). 
25. Concerning the identity of things it is argue that the notion of 'the same thing' and hence of 'same' and of 'thing', necessarily implies that identifying a thing as the SAME is to identify it as that which in different situations of observation, description and cognition, may be differently observed, cognised and described. It is not because a thing retains the same, unchanged "essence" or "substance" in different situations in which it may be observed and correctly cognised and described in different ways that we have a notion of 'the same thing'. On the contrary, a thing may be identified as THE SAME THING precisely in virtue of being the thing which in different situations may be correctly cognised and described in these and those DIFFERENT ways. Indeed, the very notion that we may acquire more knowledge about the same thing, e.g. by arranging situations in which the thing may be investigated with new and different possibilities of observation and descriptions, is incompatible with the view that any of the descriptions of the thing put forward in any of the situations in which it may be observed, known and investigated, and any property of the thing uncovered in such situations, is IDENTICAL with the thing. Rather, any consistent notion of a thing being some particular thing of which we may acquire more and different knowledge in different situations, would seem to require that the knowledge and description of it in any of the situations in which it may be observed and described is LOGICALLY related to other descriptions and knowledge of the same thing in other situations. This assumption about 'identity' may be formulated thus:
To identify a thing as 'the same thing' logically implies that more may be said and known about it.
26. I contend that both the assumptions concerning the dependency of the notion of 'truth' on the notion of 'others', and the dependency of the notion of the 'identity' of a thing on different descriptions of it, are assumptions which have status as principles, for just the same reasons as the assumptions of the general correctness of knowledge and language. That is, we cannot talk consistently of either inter- subjectivity between persons or of the identity of things without presupposing these assumptions. Neither can these assumptions be proved nor disproved without being conceded.
27. If the principles derived from the arguments and assumptions in the book are valid, a fair number of traditional questions and the answers attempted in classical as well as more recent theories of Mind, Language, Reference, Identity and Truth will have to be reconsidered - and so will suggestions that solutions to these questions may be either obtained or verified by empirical psychological investigations. On the other hand, a whole range of questions about key-issues concerning cognition, language and action may be dealt with in much more straight-forward and consistent ways - be it philosophically or psychologically, theoretically or empirically. If so, I think we shall be able to see the beginnings of a consistent foundation of assumptions and principles that psychologists will have to take for granted and agree, and on which a science of psychology may be based. These are assumptions and principles which may serve as a guide as to what questions we may ask and hope to answer in our psychological investigations, and as to what concepts and theories about psychological phenomena will stand up.
. cf. among others Bruner, (1990), Giorgio (1985), Koch & Leary (1985), Miller (1985), Pylyshyn (1987), and Smith, Harr and Van Langenhove (1995).
. Physicalism, Scientism, Eliminative Materialism, Computational Functionalism, Biologism, etc.
. Including Structualism and various of its Deconstructivist, Relativist, Anti-realist and Irrealist successors.
. Even strong opponents to Naturalist reduction, as for example John Searle, Thomas Nagel and Collin McGinn, share the further intuition of Naturalism, almost universally held by the scientific community, that everything which exists objectively in the universe must be of a physical nature, and thus must have physical explanations. To psychologists (especially within so called "experimental" psychology) adhering to Naturalism, this assumption fixes the limits to what may and what may not be acceptable psychological theorizing. Hence, a psychological theory which is not compatible with the assumption of the purely physical nature of the human mind-brain system, or a theory which claims non-physical psychological entities, is not scientific and can be ruled out a priori. Indeed, neither theories nor data from research on psychological phenomena and events can attain scientific status unless they can be made consistent with the rest of the natural sciences. For a presentation and discussion of various versions of Naturalism in psychology, see Seager (1991).
. The following quotation from Nagel will have to suffice here as an example of how assumptions of Naturalism and Constructivism may lead to similar consequences. Nagel, by no means a proponent of Naturalist REDUCTION, writes: "What has made modern physical science possible is the method of investigating the observable physical world not with respect to the way it appears to our senses - to the species-specific view of human perceivers - but rather as an objective realm existing independently of our minds". [...] "It was a condition for the remarkable advances [of the physical sciences] that the subjective appearances of things be excluded from what had to be explained and described by our physical theories. And what was done with those appearances instead was that they were detached from the physical world and relocated in our minds. The whole idea of objective physical reality depends on excluding the subjective appearances from the external world and consigning them to the mind instead" (1994, pp 65-66). - This view, reminiscent of the Galilean and Cartesian division between the "subjective qualitative" and "objective quantitative", seems to be shared by a large number of philosophers ranging from "soft" type B-materialists through to "hard nosed" type A materialists. Although this view posits "mental construction" only of things in our familiar world, it inevitably leads to inconsistencies in the notions of "objectivity" and "subjectivity" similar to those found in the Constructivist position. This becomes clear if we can agree that descriptions of the conditions for carrying out physical investigations rely on ordinary everyday observations and descriptions of the situations in which such investigations are carried out (i.e. of the laboratory, measuring instruments, their position in space relative to other things in the experimental set-up, etc.) and agree, therefore, that the descriptions and observations of these conditions necessarily have to be considered just as true and objective as the description and observations of the physical phenomena being investigated. To assume otherwise would be to assume that it is possible to arrive at true descriptions of what exists objectively in physical reality on the basis of observations and descriptions of things which do not themselves exist objectively in reality - but rather in the "realm" of our minds.
. For recent arguments to this effect, see. e.g. McGinn (1989), and Nagel (1986, 1994).
. We could not express doubt or deny that we know the meaning of 'true' and 'correct', nor how to use 'true' and 'correct' correctly, without having and using a notion of 'true' and 'correct' when expressing such doubts or denial of which we presuppose that we know the meaning and correct use. For the same reason it could not be proven or explained that we know the meaning of and how correctly to use the notions of 'true' and 'correct'.
. Cf. the discussions on "Zombie-ism" in the volume by Block, N. Flanagan, O. and Gzeldere, G. (1997)
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