Moritz Schlick began his academic career as a physicist before transitioning to philosophy. In 1904 he achieved a PhD from the University of Berlin in physics, under the supervision of Max Planck, where his thesis investigated the behavior of light when refracted using different mediums. He began his journey in philosophy with a volume on eudaimonism, a fact many forget about the famous Schlick. He didn’t spend much time on value theory before writing “General Theory of Knowledge”, the subject of my writing here today. Schlick aims to provide answers for some of the biggest problems in philosophy at the time, the thing in itself (ding in sich) of Kant, the unity of consciousness, criterion of truth, and more. What makes Schlick’s work stand out amongst his contemporaries is his methodology. He’s not coming from a religious background, or from a traditional philosophy background, he’s a physicist. Schlick’s idea is to attack the problems of truth and knowledge in philosophy by seeing how the sciences come up with criteria for truth and knowledge, and replicating it in the everyday situations that philosophy evokes. One can say that he believes that philosophy must obey the established criterions of verification and reduction (reduction of two concepts to one as scientific discovery for Schlick) if it is to make real progress. What Schlick was picking up, inspired by Mach, Avenarius, and Russell, would take off as the dominant methodology of philosophy for decades to come. Many consider Schlick’s work underappreciated, and perhaps one of the earliest books we can consider firmly as, “epistemology” and “analytic philosophy”. There is no doubt that Schlick’s General Theory of Knowledge commanded the respect of philosophers for decades, and the impact of his writing whether we realize it or not is still felt in the field of analytic philosophy.

Schlick begins by admitting that the question of ‘what is knowledge’ and ‘how do we come to knowledge’ can be difficult. However, he frames it much differently, drawing an analogy with physiology. Man was able to move his body freely before scholars could explain the how and the why, and scientists have continued to research and discover, unbothered by the philosopher’s trouble in explaining the possibility and explanation of knowledge. Scientific knowledge constitutes real phenomena –we can see it and feel it– which the scientists surely encounter as one encounters his arm or body. To Schlick, the point is that to move our body we do not need complete understanding of physiology, just like in science, we don’t need a complete theory of knowledge for that scientific knowledge to be legitimate. Epistemology cannot issue decrees that outline what isn’t knowledge, its only role is therefore to “clarify and interpret that knowledge.” Here Schlick outlines an early conception of the goal of philosophy of science, one which will impact and influence other philosophers of science much later in the 20th century. 

Schlick finishes his first section by further motivating the requirement of philosophy in comprehending the sciences. The ultimate basis of the general sciences, from consciousness in psychology, to axioms in mathematics, at their bottom admit only a philosophical or epistemological clarification. In fact, they demand an epistemological clarification for Schlick, especially for she who is unwilling to call an arbitrary end to the theoretical impulses which arise from the analysis of the sciences at their core. 

The central goal of this book is to break down the questions that lie within a bigger question: “What is knowledge?”. For most the answer to this question seems obvious, there’s no need for further elucidation. In everyday usage this can be prudent, however in philosophy, explanation is necessary as the concept of cognition tacitly assumed by most is not useful in philosophical endeavour. 

As a point on methodology, Schlick notes that some might aim for knowledge to be secured (as in defined) at a later stage or even at the conclusion of one’s undertaking of epistemology. But accepting this methodology, as philosophers have done for centuries, makes the boundaries of epistemology’s field of research and the correct point of entry into the field left in obscurity. Therefore, every discipline (including epistemology) must rest upon an implicit delimitation of its field. Before light was discovered as electrical waves, we still were able to define it as a sensation made aware by our eyes, by that same token, whatever we can say about knowledge in a philosophical system, it must be possible independently of that system to create an adequate definition. This holds for the concept of knowledge. Schlick holds that in science we really do possess knowledge and advancements in knowledge, which implies that the sciences have some sort of criterion for selecting genuine knowledge and what that knowledge consists of. So the sciences must contain a full definition of the concept, and philosophers simply need to infer it from the research and use the definition as a firm starting point to begin the deliberation on epistemology.

Only this way can pseudo problems (which have plagued philosophy since time immemorial) be avoided. What are pseudo problems? For Schlick these are questions which are asked with a poorly or non defined meaning of ‘know’. Schlick gives examples like “Can man know the infinite?” or “Can we know things as they are in themselves?” as pseudo problems. Once a better definition of ‘knowing’ is spelled out according to Schlick, it’s immediately evident that the question is poorly put or that the question has a precise and unanticipated answer.

So then the question, what is knowing in everyday, mundane situations? For Schlick it’s a resemblance. When you see something in the distance, brown and round, one can tell it’s an animal, as one gets closer they realize it’s a dog, until finally they are close enough to identify the dog as their own. When one sees the brown object, from childhood they are able to identify the object as one that resembles the class of objects which we denote in English as dogs. To say that I recognize or ‘know’ the object to be an animal, and then a dog, means that I have identified the object to resemble what I understand as a thing which fits into the class of animal and then dog. Knowing is simply to re-cognize concepts within a certain thing, to reduce something ‘unknown’ to something we are familiar with. 

This carries over to the sciences, where Schlick describes the process of coming to scientific knowledge as reducing two separate phenomena to one or the other. Proceeding in the fashion described, the number of phenomena explained by the same principles becomes greater and hence we need less principles to explain the totality of phenomena. Therefore, according to Schlick, the ultimate task of knowing is to make this minimum as small as possible. 

Continuing on the topic of scientific knowledge, Schlick points out that scientific knowledge (which he takes to have the same criterion for legitimacy as everyday knowledge) has a rigorous standard for legitimacy. This is despite the fact that our mental images are hazy and incomplete. Even more, we struggle as humans to create general images, for example of a dog, we cannot come to a true general image of a dog in our minds. Thus to reason rigorously and to come to scientific knowledge, one must do so using concepts. Concepts are different from images insofar as they are nonreal and completely determinate, discrete. Indeed they are not real, things we assume in place of images with exact contents. Humans operate with these concepts as if they were exact images whose properties we can always recognize with complete certainty. These properties of the concept are given by means of stipulations which all together constitute the definition of the concept, or its intension. The definition specifies the common name (sign, signal in Schlick’s words) we are to use to represent all objects which are set forth in the definition. Strictly speaking, concepts don’t exist. There is only conceptual function, which can be performed by various mental acts or by names/signs. The importance of the conceptual function lies in its task of designating or signifying things with their corresponding definition. Truth and concepts consist in their being signs, and always presuppose someone who designates, who desires to set up a correspondence.

Concepts, according to Schlick exist only so that we can make judgements, which he defines as signs for the existence of a relation between objects. Therefore whenever we make a judgement, we seek to designate a set of facts (real or conceptual). This is the great task of knowledge, designating particular objects with the help of general concepts. In Schlick’s words “The concept that corresponds with or is coordinated to the known object stands in certain relations of subsumption to the concepts through which the object becomes known, and the existence of these relations is precisely the fact that the judgment serves to designate.” pg. 39. So what then is truth? Well, truth becomes the unique coordination of objects to a particular sign. What does unique mean in Schlick’s vocabulary? It means the same sign can never mean different objects. A judgment which uniquely designates a set of facts we can call true. To define a concept implicitly, you simply determine it by it’s relations to other concepts. However, to apply a concept to reality, is to choose out of the countless amount of relations in the world, a certain few and to designate this unit as a name.

Here Schlick builds on the work of those like Henri Poincaré in fleshing out a conventionalist philosophy, which he again defines as the arbitrary selection of certain relations in the world denoted with a sign. 

One of Schlick’s main goals in writing this book is to create a counter balance to the dominant Neo-Kantian philosophy in Germany at the time. As we see later, he refutes concepts like transcendent metaphysics, but the analytic-synthetic distinction is one of the few points Schlick welcomes in from Kant’s Critique of Pure Reason. In fact, this distinction will become the core of the Logical Positivist movement he pioneers in the coming years after this book is published, and will arguably be the downfall of the movement with W.V.O Quine’s famous work Two Dogmas of Empiricism. Schlick believes it to be so irrefutable, that he says “The partitioning of judgments into analytic and synthetic is thus something quite well defined and objectively valid… the point is so evident that I would not have mentioned it were not certain misunderstandings about it present in the literature.” pg 76. These misunderstandings stem from the fact, as Schlick believes, that some authors do not make it key to their interpretation that the nature and content of a concept are to be completely made up by the features it includes. Seemingly obvious, this concept, or what Schlick calls definitions, are analytic and make up the backbone of his epistemology. 

Moving on, Schlick comes to a point I believe to still be hotly contested, intuition based philosophy. Many metaphysicians at the time (and today) believed that intuition brings us genuine knowledge. The green stem of a plant next to my computer is green. That is an intuition that brings knowledge. To Schlick, objects in intuition are given, they don’t provide knowledge. Intuition is experience, but cognition and knowledge is something much more, i.e. the complex process of unique designation of real world fact to sign. Clearly, our intuition deceives us and can lead us astray. Our conceptual function within our brain creates fictional, yet pure concepts which we can then reason with to come to knowledge. Knowledge, that is, that meets the standards of those like Descartes. Schlick positions his view as the antidote to Kant’s “ding in sich”, the thing in itself, saying that if we consider knowledge to be a unique designation, and intuition to be what is given, then it is not necessary to know something in itself. After all, how could one represent something without representation. Contradictio in adjecto. 

Let me reestablish Schlick’s idea that knowledge is when we reduce two terms to one another by finding a third term again in each, creating a connection between them. This is evidence in our scientific discoveries, the most rigorous pieces of knowledge we possess. We say that the third term is derived from the first two, with the first two propositions being the premises and the third the conclusion, thus creating a syllogism. Although regular thought likely doesn’t occur in syllogism, according to Schlick, this doesn’t mean they can’t be a tool for  rigorous systems like the exact sciences or mathematics. Again, they science operates using pure concepts, which allow for reduction to other complete concepts. Another interesting fact about the syllogistic nature of scientific reasoning in the universal aspect of the conclusion. The truths of the conclusion are not new, they are contained universally within the major premises. The establishment of the universality in the conclusion ensures that the conclusions apply to all instances covered by the premises, affirming their necessity. Worth it to mention is that the validity of certain conclusions is contingent upon verification against potential mental errors. What this means is that while we can theoretically doubt all certainty, in practice, we rely on verification processes to assure ourselves of correctness. Scientific syllogistic reasoning reveals implicit universality in premises, the certainty of the universality depends on empirical verification which guards against psychological error. 

Underlying experience is a constant, “unity of consciousness” as Schlick puts it. Consciousness is not a collection of contents, a theater of sensations, as Hume might put it. Instead, there is a unified while that organizes experiences into a single, coherent awareness. Schlick admits that such a unity is inexplicable, although necessary. It is what allows us to recall, and is the basis of what we colloquially call memory. Memory as a fact of consciousness is the precondition that provides a guarantee of the fundamental nature of thought. Through the process we can recall concepts, judgements, signs, and more, as well as designating an “I” throughout to reference from. A Kantian flavor thus emerges from Schlick’s work once again, with a priori cognitive faculties being a necessary for human thought and consciousness at all. 

Having established that the data of consciousness can be imprecise, Schlick must now salvage the idea of truth in reality. Remember, truth is defined simply; the uniqueness of the correlation of judgments with facts. The scientific procedure of verification is then the process we can use to check if a unique designation has been obtained by a judgment (like the sentence, “that object is a chair” is a judgment). Judgments are like hypotheses in science, they’re advanced first and then whether a unique correlation is found determines the validity of the judgement. Schlick finds that every assertion about reality is connected with a chain of judgments to immediately given facts that determine the truth or falsity of the judgement. There is a sense in which empirical truths that depend on experience can only be confirmed with probability. However, conceptual truths have certainty through identity with definitions. This means that a priori valid judgments about nature would need to prescribe laws to itself, a revealing development in the journey for absolute empirical certainty. So, Schlick helps us realize that a judgement being true only has any sort of meaning within the framework of concepts and definitional framework we construct for ourselves, another nod toward conventionalist philosophy that will dominate the next half century at least. 

A good writing on Schlick would be incomplete without an attack on metaphysical doctrines. Going again at the thing in itself, Schlick lambasts those who posit anything beyond experience. The problem is formulated by Kant and made to be unsolvable. The ding in sich as well as all other nonphysical, metaphysical entities are by definition beyond observation, and so no evidence can ever confirm or refute claims about them. Conversations and discussions surrounding these concepts are empty, they add nothing to knowledge since we can’t anchor the conversation to experience. Moreover, that an object is not produced by our designation, or naming of it, that it is independent of it and can exist without correlation to some sign is contained within the concept of designating itself. For example, calling a mountain “Everest” doesn’t bring the mountain into existence, it refers to something that already exists. The independence of objects is already evident in how reference works, without needing to posit an unknowable reality being appearances.