Structure of Science
PhiloSign
The Structure of Science
Peirce is one of the few thinkers, alongside Aristotle and Kant, who constructed their philosophy in an architectural form. One instantion of this architectonic form is Peirce’s Classification of the Sciences, which orders the sciences in a hierarchical order relative to each other.
This is not a normative order implying that one science is more important than another, rather the aim is to clarify the interdependencies between sciences. The guiding principle of Peirce’s classification is simple: “one science depends upon another for fundamental principles, but does not furnish such principles to that other.” (CP 1.180)
In other words, the more general science produces principles and laws for the more specific science, which in turn produces facts and data for the more general science. The more general science thus serves as the framework through which the narrower science can interpret its observations. Conversely, the observations of the narrower science are suggestions and cases that the more general science should be able to incorporate.
…the sciences form a sort of ladder descending into the well of truth, each one leading on to another, those which are more concrete and special drawing their principles from those which are more abstract and general. CP 2.119
The classification of the sciences provides a great overview of the breadth and systematic nature of Peirce’s thought. Furthermore, it acts as a kind of map of Peirce’s philosophy preventing us from getting lost in the semiotic maze.
In this text, I’m not able to do full justice to the classification. My purpose is just to offer a broad overview of its structure and possibilities.
General Structure of the Classification
So, let’s take a look at the classification itself. The sciences become:
- more practical as we move down the diagram, and
- more minutely classified as we move to the right in the diagram.
In the structure above there are various levels classifications. The most fundamental level is the distinction between Theoretical Sciences and Practical Sciences.
According to Peirce, theoretical sciences are pursued simply to discover the truth, regardless of the practical value or what is done with that knowledge. The purpose of practical science, on the other hand, is to serve practical purposes and act as an practical ‘art’ of achieving something concrete.
The key word here is purpose. Theoretical science is independent of any specific ‘worldly’ purpose for applying the knowledge. For example, nuclear physics is independent of its applications to atomic bombs. Practical sciences, in contrast, serve a particular purpose. For instance, medicine serves our health, engineering helps us to construct infrastructure, and navigation assists with orientation.
Peirce provided no classification of the practical sciences as it didn’t “concern us in logic”. Furthermore one easily becomes “utterly bewildered by its motley crowd” of sciences (CP 1.243).1
Theoretical sciences divides into the Science of Discovery and the Science of Review. Science of discovery is the branch which we would consider science in the ordinary sense of the term. Here we find the familiar sciences like philosophy, physics, chemistry, psychology, sociology etc. We’ll take a closer look on it in a moment.
The task of science of review is to update and reflect on the classification itself. The architecture is not an eternal and rigid structure, rather, new sciences must be integrated into the structure, and older ones may merge into other sciences. Science is a continuously evolving social project, and the architecture must change along with it.
…the classifications certainly ought to differ from age to age. If Plato’s classification was satisfactory in his day, it cannot be good today; and if it be good now, the inference will be that it was bad when he proposed it. CP 1.203
However, there is also a philosophical aspect in the science of review. It is the philosophy of science.
By “science of review” is meant the business of those who occupy themselves with arranging the results of discovery, beginning with digests, and going on to endeavor to form a philosophy of science. Such is the nature of Humboldt’s Cosmos, of Comte’s Philosophie positive, and of Spencer’s Synthetic Philosophy. The classification of the sciences belongs to this department. CP 1.182
It is fascinating how Peirce added this reflective part of the classification into the classification itself. Furthermore, following the logic of the classification, the science of review is dependent on the science of discovery. In other words, it must take all the sciences of discovery into account when formulating the classification, but as it is more general than practical science, being a theoretical science, it is independent of any worldly purpose. Truly a genius move in my opinion.
But now it is time to take a closer look on the science of discovery which is the most important part of the classification.
Science of Discovery
The most general science is Mathematics, which “studies what is and what is not logically possible, without making itself responsible for its actual existence.” (CP 1.184). Mathematics draws conclusions from hypotheses without any concern for whether these hypotheses correspond to any reality. Thus, mathematics is not an empirical science, but the most theoretical science possible. The mathematician is in no need of any other science. There is no scientific finding that would alter the work of the mathematician. The area of a circle on a plane would always be \(\pi r^2\) regardless of any empirical finding.
The next science after mathematics is Philosophy, which is an empirical science because, unlike mathematics, philosophy is interested not only what is logically possible, but in what is also real and true.
Philosophy studies the world through the general experience that we all share. This is the everyday Lifeworld (Lebenswelt), that we face every moment of our life. This means that all philosophical theories, claims, and hypotheses are verifiable by everyone because we all share this same general experience.
In contrast, the Special Sciences, which come after philosophy, study reality through specific experiences. The observations of the special sciences are not open to everyone; they require either instruments (such as telescopes, microscopes, particle accelerators) or specialized insights (a sociologist “sees” the structures behind everyday life, a psychologist “perceives” personality traits). I’ll return to this distinction later.
Philosophy is further divided into three parts: Phenomenology, Normative Sciences, and Metaphysics. Phenomenology (or Phaneroscopy) studies what is universally present to the mind in all possible experiences without assessing whether the experience is beautiful, good, or even true. It tries to discover the most general aspects of reality that are present in all possible experiences – even in dreams or hallucinations. Peirce discovers phenomenologically the Three Categories as the most fundamental structure of reality.
The inquiry into Beauty, Goodness and Truth falls under the domain of Normative Sciences, which are also divided into three: Aesthetics, Ethics, and Logic (i.e. Semiotics). The purpose of aesthetics is to describe and study the ideals to which other normative sciences conform. Ethics investigates the kind of actions that would lead toward these ideals. Logic, in turn, studies the normativity of thought and reasoning, and thus depends on the ideals of aesthetics and the self-control of ethics.
Finally, the last branch of philosophy is Metaphysics which studies what is ultimately true in our cosmos, being the ‘descriptive branch of philosophy’. It observes the most general characteristics of the cosmos as “the science of Reality” (CP 5.121). Metaphysics provides thus the general framework (Weltanschaugung) for the special sciences. The now common idea that physics could do without metaphysics (and philosophy) isn’t feasible for Peirce:
[Physics] cannot avoid depending upon Metaphysics. It is when they promise themselves that they will not make any metaphysical assumptions that they are most in danger of slipping too deep into the metaphysical slough for deliverance, precisely because one cannot exercise control and criticism of what one does unconsciously. CP 2.121
Special Sciences
For Peirce, the physicist must rely on metaphysics, whose task is to study the nature of reality. But isn’t this exactly what the physicist also aims to do? This question leads us back to the distinction between philosophical observation and the observations in special sciences. This is the distinction between Cenoscopic Sciences and Ideoscopic Sciences.
These words sound fancy, but the distinction itself is rather simple. The observations in cenoscopic sciences (philosophy) are about our everyday experience – about the every waking hour of our lives. These observations don’t require any special instruments and are thus open to everyone. Although these observation can be made at every moment all of the time, the difficulty lies precisely in the pervasiveness of these experiences:
These observations escape the untrained eye precisely because they permeate our whole lives, just as a man who never takes off his blue spectacles soon ceases to see the blue tinge. Evidently, therefore, no microscope or sensitive film would be of the least use in this class. The observation is observation in a peculiar, yet perfectly legitimate, sense. If philosophy glances now and then at the results of special sciences, it is only as a sort of condiment to excite its own proper observation CP 1.241
Scott Randall Paine puts its nicely in his text On the Cenoscopic and the Idioscopic
In cenoscopy, things escape the eye not by being hidden by virtue of their tininess or hugeness, or their extension over eons of time or involvement in hyper-complexities of culture, but simply by their commonness. Their very obviousness requires a conscious direction of our attention, like that needed to notice the ticking of a clock that your ears were hearing all the while you conversed with someone, but which remained unperceived because you were otherwise occupied. Scott Randall Paine
Therefore, metaphysics, as a cenoscopic science, studies reality through general experience in a way that anyone can participate in. Are individuals real? Is my inner world separate from the external one? Is time real? What is consciousness? Is the world matter or spirit? These are questions we can observe through our everyday experience.
Maybe part of the confusion we face currently in the meaning crisis stems from the misplaced pursuit of answering these fundamental philosophical questions through special sciences and their special observations. We can’t see the forest with out the trees.
In turn, Ideoscopy depends “upon special observation … either instrumental or given by training.” (CP 1.242). Therefore, physics, as an ideoscopic science, uses various instruments to study on topics like the structure of the atom, which are not immediately accessible to us. However, physicists use the more general framework provided by metaphysics (for instance the world views of materialism and idealism or philosophical ideas about the nature of causation).
In our current era, some popular physicists seem to have forgotten this important fact. They regard philosophy as an ancient remnant of science, something destined to fade away as its questions are answered by natural scientists (special scientists). However, they seem to forget the observer when they observe.
No matter how advanced the data we gather or how sophisticated the instruments we build, all these observations remain embedded in our common experience. Every observation is situated in the Lifeworld. The scientist grabs their cup of coffee, sits before a screen, and this aspect of experience is more general and fundamental than the special observation itself.
Therefore, one cannot escape the fact that philosophy – as the discipline that inquires into this all-encompassing, shared experience – precedes, and is embedded, in all the special sciences.
Another way to see this is to ask the physicist why they reason the way they do. What are the principles of reasoning they ought to follow? This is a philosophical question that cannot be settled by observing the universe with instruments. Questions like “What counts as evidence?” “How do we justify inference?” or “What is the nature of causation?” are questions that special sciences cannot answer with a microscope or a particle accelerator. These are philosophical questions that precede any scientific inquiry.
Triadic Division of Special Sciences
Peirce divides special sciences into Physical and Psychical sciences which are further divided into (1) Nomological, (2) Classificatory, and (3) Descriptive branches.
Nomological Sciences seeks to discover the universal laws guiding either by efficient causation (physical) or by final causation (psychical).
Classificatory sciences explore the general types of manifestation in both the physical and the psychical sciences, organizing them into structured classifications. Examples include the periodic table of elements in chemistry, Carl von Linné’s taxonomy in biology, personality types in psychology, and societal classifications in sociology.
Descriptive Sciences inquire particular manifestations of either physical or psychical. For example astronomy describes particular objects in our cosmos. In the same manner history describes particular eras of the past or biography describes particular people.
Physical Sciences
Nomological physics discovers the ubiquitous phenomena of the physical universe, formulates their laws, and measures their constants. It draws upon metaphysics and upon mathematics for principles. Classificatory physics describes and classifies physical forms and seeks to explain them by the laws discovered by nomological physics with which it ultimately tends to coalesce. Descriptive physics describes individual objects – the earth and the heavens – endeavors to explain their phenomena by the principles of nomological and classificatory physics, and tends ultimately itself to become classificatory. CP 1.188 (italics mine)
I will not delve into all of the sciences here. Instead, I want to concentrate on the hierarchies and interdependencies between the sciences. As already said, the logic of the classification is that the more general sciences provides principles for the more specific sciences.
Let’s take biology, for example, which belongs to the special sciences, specifically the classificatory special sciences. Which broader sciences serve as a framework for it? Biology relies heavily on the discoveries of chemistry, making chemistry one of biology’s frameworks. Similarly, physical laws and principles are factors that a biologist must consider in their research. Additionally, a biologist is a scientist who seeks truth by making inferences from various signs, relying on logic or semiotics in reasoning, which is guided ultimately by ethics and aesthetics.
Physics, on the other hand, does not need chemistry or biology in its research. When studying the structure of the atom, its chemical properties or function in the biological organism do not influence the research. The fundamental structure of the atom is more general than its chemical properties or biological functions.
Psychical Sciences
Nomological psychics discovers the general elements and laws of mental phenomena. It is greatly influenced by phenomenology, by logic, by metaphysics, and by biology (a branch of classificatory physics). Classificatory psychics classifies products of mind and endeavors to explain them on psychological principles. At present it is far too much in its infancy (except linguistics, to which reference will be made below) to approach very closely to psychology. It borrows from psychology and from physics. Descriptive psychics endeavors in the first place to describe individual manifestations of mind, whether they be permanent works or actions; and to that task it joins that of endeavoring to explain them on the principles of psychology and ethnology. It borrows from geography (a branch of descriptive physics), from astronomy (another branch) and from other branches of physical and psychical science. CP 1.189 (italics mine)
According to Peirce, the most general psychical science is experimental psychology, whose task is to study “the general phenomena of mind” (CP 1.199). I believe that contemporary cognitive science comes closest to this discipline, as long as we understand cognitive science as a field that studies the general laws concerning the mind, and not only the brain.
After cognitive science come the classificatory psychical sciences. These sciences study various types of mental manifestations using the general mental laws discovered by cognitive sciences as their framework. Although these sciences are referred to as classificatory sciences, they do much more than pure classification. The first classificatory psychical science is Psychology, followed by Linguistics and Ethnology, which I have replaced with Sociology since ethnology is now considered a subfield of anthropology. I believe sociology is a more appropriate term because it generally involves the study of the nature of communities and societies.
After the classificatory psychical sciences come the descriptive psychical sciences, which aim to describe individual historical manifestations of the mind and explain them using cognitive and sociological principles. The key difference between the classificatory and descriptive psychical sciences is that the former studies mental types, while the latter examines particular mental manifestations. For example, psychology describes the general features of the mind, while a biography describes the features of a particular mind. Or sociology studies types of society and history societies that have already manifested.
The first descriptive psychical science is History, followed by Biography. This means that any biography should always be seen within a historical framework, as we are all products of our time. Finally, the task of Criticism is to “describe individual manifestations of mind” (CP 1.189), which must always be understood as part of history and biography.
Summary
Peirce’s Classification of the sciences is a remarkable structure that deserves much more attention and is in need of an updated reflection. Although the the classification seeks to describe the real organisation and structure of the scientific project, especially the structure of philosophy seems to be more of a philosophical statement than a descriptive project. A closer look on the reasoning behind the structure of philosophy would be a source of many fruitful insights.
Formulating the classification of the practical sciences would be an interesting task. For example, we could say that engineering (‘physics’) is more general than taking care of plants (‘biology’).↩︎