This essay was written by guest-author Will Porter.


Epistemology is arguably one of the most fundamental branches of philosophy, and certainly has been the one that has consumed much of my own thought for quite some time. Its primary task is to construct a theory of knowledge, discussing how human beings come to attain knowledge and the nature of knowledge once attained.
Ludwig von Mises, the founder of the Praxeological Austrian School of economics, –and later expounded on further by anteceding philosopher Hans Hermann Hoppe — delved into matters far surpassing that of only economics. Praxeology gives us insights into other areas of philosophy, especially epistemology, by way of distinguishing between that which can be known a priori, using logical deduction and reflection,and that which can be known only a posteriori, using observation to affirm or falsify a hypothesis. While a priori deduction, once established as true, holds absolutely for all times and places, a posteriori truths are hypothetical and tentative.
This fundamentally means that there are two realms of knowledge that we can speak of. The first being the causal, the mechanistic material world, governed by a posteriori laws established empirically.
The other kind of knowledge is that of the a priori realm, as said above, validated by logical rigor.
This latter set of knowledge is known by reflection on what is necessarily true. Though the building blocks of the concepts we reflect on are always attained empirically through the senses (at least initially), we can then employ these concepts, once grasped, to establish propositions that are true a priori, necessary to the structure of thought, as will be touched on more below.
(This is in line with Aristotle’s Peripatetic dictum: “Nihil in intellectu nisi prius fuerit in sensu” “Nothing is in the intellect without first being in the senses”. The a priori realm of knowledge was accounted for and tacked on by the Rationalist philosopher Leibniz with his addition to the maxim: “…nisi intellectus ipsi“  “…except the intellect itself.”)
To bolster this fundamental distinction with more substantial weight, as touched upon above slightly,these two realms of knowledge can be distinguished further as the Causal and the Teleological.
The realm of empirical knowledge concerns the mechanistic, causally-oriented external physical reality.The realm of a priori knowledge concerns that of the teleologically-oriented (purpose-oriented), that of the internal realm of thought, and the implementation of such thought, so to speak, in action (or at least that which guides action).
These two areas of knowledge are inextricably tied to one another. The causal world could not be interacted with, or purposely observed and known about without the teleological, purpose driven entity engaging in action to accomplish these tasks as ends. Thought needs a causally-structured external reality for action to take place in, for conscious implementation of purposes and preferences to take their course in making changes.

From Hans Hoppe: ”In so understanding causality as a necessary presupposition of action, it is also immediately implied that its range of applicability must then be delineated a priori by that of the category of teleology. Indeed, both categories are strictly exclusive and complementary. Action presupposes a causally structured observational reality, but the reality of action which we can understand as requiring such structure, is not itself causally structured. Instead, it is a reality that must be categorized teleologically, as purpose-directed, meaningful behavior.”

Action is the medium through which thought meets external reality, the intermediary by which the teleological meets the causal. Action is the implementation of knowledge in a conscious or purposeful manner to inflict change into the external, causally-governed world.

Because of this nature of humans necessarily as actors, as choice-making-external-world-changers (indeed a clumsy, yet true, way to phrase it), this can be said to constrain the realm of what can be possibly known a priori. The a priori categories, the laws of thought, are constrained and defined by the teleological laws of Praxeology, and by the categories of action that Praxeology entails.

This is so because action is the boundary between thought and physical reality. Thought can only be implemented into reality via action. The conceptual line between where the structure of thought ends and the external universe begins can be found in action.

Here we do not have a skeptical project. Because I sit here writing this, because I know I engage in action on an unrelenting and constant basis, because I formulate goals (consciously or not), have purposes and values, and because I make choices, setting aside alternatives and incurring costs, I cannot rationally attempt to question my own capacity to act. An argument that by its very utterance immediately demonstrates itself to be false is not worthy of taking up. The general tone of this project is that we know that we do get some things accomplished. We dress ourselves, we walk across the street, we interact with others, and we build rocket ships based on mathematical principles and fire them into space successfully.

The human organism is not a biologically, or in any way, ideal being, but we do certainly have a grasp on some fundamentals. We have survived to reach the top of the food chain and accomplish astonishing feats relative to every other species. There must be something that is happening correctly in our capacity to identify abstract conceptual principles and discern where and when they apply to reality, rooting out contradictions and anomalies wherever possible. So I here make the bold assertion that the human mind is capable of grasping some significant piece of that which is , that which exists external to ourselves.

The nature of this argument is more Assertoric (since/then) than a Hypothetical (if/then) one. We here say because/since A is true, B, C, and D follow. Because we know that humans act, some things must hold to be true. Our work here is not to question whether man truly attains knowledge, but in knowing that we clearly do, to discern between a conceptual taxonomy of different kinds of knowledge once attained.

We here must make known the vital role of knowledge in action, and also the inextricably related role that language and proposition-making (truth/validity claims) play in knowledge.

Without knowledge, action would be impossible, since a necessary part of action requires the identification of a certain state of affairs, and discerning between that and a more desirable one, which one then acts to attain. The only way to formulate and give a conceptual structure to such knowledge is by the means of language, particularly by propositions and truth claims which are or can be expressed in the form of argumentation.

Argumentation, as it relates to knowledge and truth, is the necessary result of our ability to identify and distinguish things in a conceptual framework. If one tried to dispute the fact that truth is possible to attain and that language has meaning, he would immediately refute himself in the course of making the precise kind of truth claim, using meaningful linguistic-communication, which he sought to deny existence to. Even if he merely uttered this, or thought it to himself, he still would have had to implement his conceptual framework of knowledge as expressed by meaning attached to symbolic patterns called language.

Just as one cannot say that one does not act, one can also not argue that one cannot argue. These truths are established as absolutely logically incontestable, whether one attempts to refute them with logic alone, or by using empirical evidence attained through observation.

The epistemological structure of a priori knowledge is determined, in a sense, by man’s nature as an actor, and to even make such recognition about the truth of action, the possibility of argument and the possibility of truth-validity are presupposed as fundamental categories of action itself. The immutable categories of thought, as formulated by Kant, must be seen as an integral part of action, since action requires knowledge as a necessary ingredient.

Since knowledge is necessary to action, we can say that knowledge plays a peculiar role as an action category. Truth-validity determination is an essential part of how action is guided, whether such determinations turn out to be right or wrong. Was it not for our capacity to distinguish between that which we deem true and false, we could not even tie our own shoes. Our action is always based on the result of that which we determine is true, whether we act against it or accept it. Knowledge is a propellant and a means for action, and yet action could not be discussed or known about without knowledge or the means to convey knowledge through language.

The task of epistemology has traditionally been to establish that which can be known a priori, and that which can be known (also known a priori in a methodological sense) to not be the realm of a priori knowledge, to determine the constraints or limitations on possible a priori knowledge; that which we can know just by thinking about it.

We here make this distinction between those two realms of knowledge with the causal (AKA empirical/a posteriori) and the teleological (aka reflective/a priori). This delineates the limits of a priori knowledge.
The Empiricist or Skeptic charge that this dualism leads to an epistemic idealism can be dealt with now.The old Rationalists, like Leibniz and Kant, implied in certain works that reality conforms to knowledge,rather than the other way around. This means some sort of idealism must be true, where thought creates reality, or precedes it.
But with our Praxeological theory, instead of the old-Rationalist model of an active mind that meets reality with its own structure, we can further elaborate on such a mind as being that of the Praxeological actor.
With this in view, we can now see that Kant’s ideal a priori categories of thought become for us the Praxeological categories of action, which of course must fundamentally reflect reality and the way things truly are because action is itself related to reality; it is the conscious directing or adjustment of a physical body, using knowledge, through space and time. This gives us a very realistic epistemology,rather than an untenable idealist one that either assumes a mere coincidence in the structures of thought matching reality, or that reality conforms to, and is preceded by, such structures.
The substance of the narrower, economically-related, categories of action include: Means/Ends,Cost/Price, Profit/Loss, Value, Exchange, and Good. All these go to define the a priori limits of what can be known about action without having to delve into empirical endeavors, and in fact no empirical observation could ever conceivably disprove or refute such things, since to do so would be to engage inaction using Means/Ends, making a choice and setting something else aside (Cost/Price/Exchange), and attaining or not attaining the goal you sought to reach (Profit/Loss/Value).
The wider, more extensive categories of action, as related to the structure of knowledge that action necessarily requires, include: the Principle of Causality, the Principles of Geometry (as it pertains to spatial navigation and measurement) and Arithmetic (as it pertains to repetition and therefore time), basic linguistic building blocks such as “I
s” / “Is Not” (quality), “Some” / “All” (quantity), “And” / “Or” (junctors), and the basic rules of logic I.E. the Law of Non-Contradiction and the Law of Identity.
As with the economic categories of action mentioned above, the validity of these categories as a priori could not possibly be disputed using observational examination. To even engage in observation, these things must be understood and incorporated into our thought, and therefore our action. I do not wish here to say that we all have immediate or inherent knowledge of these things, but that their explicit discovery and formulation into a truth-claim only requires reflection on what we must  already know based in our very nature as choice-making, acting creatures.
Action requires some ability to identify real qualities, quantities, spatial measurements, and all kinds of other facts about real situations to implement some effect as to make a desirable change occur. These are not self-evident or automatic truths, but truths that could not possibly be disputed once understood.
The nature of observational data is simply that of particles, light photons, and sound waves. No part of observable reality is inherently logical or conceptual in any way. The classical Rationalist conception of the active mind, as opposed to a mirror-like one, must be considered valid, although not extensive enough, not giving enough substance to this conception of the mind as one that is always active and structuring.
The rational mind must meet observational reality with its own tools, its own structure. Kant referred to this as our “Manifold of Apperception”, where our mind unifies perceptual input  and intuition into conceptual understanding. To even render the hurricane of data that constantly bombards us into something cognizable and understandable, the mind must give some basic structuring or order to it.Determining the nature of this structure, and therefore delineating what can be known a priori, just by reflecting o
n what is necessary for thought (and thought’s implementation, action), is the true task of
All of these categories, or conceptual structures, constitute what must be possible to be known a priori,purely through reflecting on our very nature as actors. These a priori categories are just as much rules of thought as they are rules reflecting the basic structure of reality, at least as far as the human mind can render it. This further illustrates how action conceptually constrains and defines the realm of pure a priori knowledge and
 further demonstrates the realistic nature of an action-based epistemology, our a priori structure of knowledge necessarily fitting with the way things are, because action must grapple with such a reality, and knowledge must guide action.
Like Kant’s Eyeglass Analogy, the structure of the rational mind is something like a
n ordering filter. The mind must filter raw sensory data through basic categories and concepts, comparing new concepts to old ones to determine whether the entity in question is altogether new or simply a unique variation on a previously-known concept. This “filter” or “structure” or “set of rules” is inherently relevant to action in that action requires knowledge as a useful and meaningful tool, and sensory data would be useless without an ordering-structure to the mind to organize concepts.
The a priori nature of these categories of action and structures of thought bridge the alleged chasm between analytic and synthetic propositions because they are absolute, analytic truths concerning real-world, observable, synthetic events and happenings, as opposed to mere tautologous word games (such as: “All bachelors are single men”). The nature of action as the link between the realm of thought (the Teleological) and the external universe (the Causal) coincide with, and lead to, this latter insight.Something that is analytic is said to be a priori and necessarily true at all times.
Something synthetic is said to be contingent, it could just as easily be otherwise. Some analytic truths are merely definitions, as is the bachelor example just given, but the type of synthetic a priori knowledge discussed above transcends the gap of being tautologous or redundant and being synthetically meaningful to the world as we experience it.
Another way of thinking about this is that we can know and understand certain things about the nature of the kind of entity that we are, hence why reflection on our own nature is possible. We, however,cannot simply reflect on the nature of a rock, or a tree, because we are indeed not rocks or trees. To discover the nature of other sorts of entities, we must engage in the scientific method, observe,hypothesize/predict, experiment/test, confirm/falsify, and repeat.
Because we are rational, acting beings, we can reflect on the nature of such rationality and action and apply our reflective findings to other rational acting entities, I.E. other people. A priori knowledge is possible concerning human action because only we, as humans, could ever know such things, only through reflecting on our own nature. Of course, it must be said, things such as human biology and bio-chemistry are empirical sciences. Don’t mistake me now to be saying all knowledge related to human beings is reflective, that would be utter absurdity. What I mean here is that determining and expounding on the conceptual nature of thought and action is an apodictic, a priori discipline.
The Empiricists
There are schools of sociological thought that actively seek to deny and refute the possible existence of such synthetic a priori truths, particularly so during the late 19th through the 20th century. The German Historical School and the Empiricists (of various stripes) were prominent voices that objected to the work of somebody like, say, Ludwig von Mises, who claimed to have deduced a corpus of economic method purely through a priori axioms.
With the analytic/synthetic distinction made above in mind, essentially the Empiricist claim was,summed up, that the two areas of knowledge consisted of analytic, a priori truths that were mere linguistic conventions, playing around with arbitrary transformation rules of symbols, tautologies. The second being hypothetical empirical knowledge, as touched on already. Although they accepted that there is indeed a dichotomy between the realms of a priori and a posteriori knowledge, they claimed that nothing from the former realm could give us any new or meaningful information. Any a priori truth,they claimed, is basically meaningless to the reality of the world as it exists.
Let us deal with this objection with one simple question. Concerning the above claim, we must ask, what kind of truth is that? It certainly boasts to tell us something new about the world or the nature of things, yet couldn’t possibly be disputed on empirical grounds, to do so would require observing every single  proposition ever uttered to ensure they all fit with one of the two kinds of knowledge described above.This objection is immediately self-refuting, since it denies existence to the very kind of proposition that it itself employs.
On the basis of its own tenets, Empiricism is an intellectual failure in the realm of the social sciences and human action. If it wishes to assert that there is no possibility of deducible-a priori propositions which also teach us new things about the world, then it has to implement precisely the sort of proposition that it seeks, through the substance of the proposition, to deny.
There is a second critique which must be addressed in regard to this school of thought.
Sociologists and economists employing a purely empirical method are essentially aping the physical sciences, like chemistry and physics. A tentative hypothesis is posited and empirical observation and experimentation are used to affirm or invalidate the proposed theory. Ignoring the obvious objection that there is no sociological or economic “laboratory” where variables can be controlled and kept constant, there is a deeper criticism that can be made about the base assumptions that the Empirical method makes.
If we are to conduct consecutive experiments with the goal of refuting or confirming a hypothetical theory, and we repeat these experiments to check whether the results confirm or fall astray from our previous predictions and past observations, we are making some unjustified assumptions about the nature of what can be known empirically.
For example, if observing Experiment A at time T1 is to have any relevance whatsoever to observations made during Experiment B at T2, what must be true for this relevance to exist? What is to bind our observations to one another, so to speak, to give us the possibility of applying past-events to the future,via predictions?
In other words, why is it not simply that at T1 we see one thing happen and at T2 we see another? Why should there ever be a problem? Why is it that T2’s results could “falsify” or “confirm” the results from T1? Without any a priori, yet synthetic, knowledge, we could never solve this problem.
The assumption is made by empiricists that reality operates on mechanical, constant, and unchanging, I.E. causal variables and that we can therefore take what we observed in the past and project it into the future, making predictions and testing them, altering variables to analyze changes in the experiment.
But this claim alone could not ever be contested using empirical methods, since to undertake in observation in hope of refuting it is to immediately assume its validity. It (the Principle of Causality) must be taken to be a meaningful a priori statement about what must be true for action and observation to be possible. Never could one, using only observational data, affirm or refute the existence or validity of causal principles in their generality. It must be assumed valid, only known about a priori, through reflection, for empirical science and the experimentation such science employs to carry any validity or explanatory weight whatsoever.
Action, not only observation in particular, assumes that there is a reality governed by constantly-operating causal-factors, which we implement changes into so we can attain our subjectively-chosen-goals. If nothing in external reality stayed constant, if, for instance, gravity had its own mind and decided its own properties on an hourly-basis, not only would science be impossible, but so would action, and therefore life altogether. Observational science is only coherent when we acknowledge a principle that is only knowable through reflective a priori thought, superseding observation and action altogether.
I urge the reader to heed this; I am not here saying that the scientific method is illegitimate in some way, quite the contrary. The task that I endeavor to fulfill is to simply establish the boundaries of appropriate application of such a method and to delineate the limits of empirical science. In regard to human action,where empirical science ends, Praxeology begins.
The social sciences, like economics or sociology, involve the study of human action and human actors. In the realm of human action, I.E. the teleological realm, there are no constantly-operating, time-indifferent causes. While action takes place in a causally-structured reality, action itself is guided not by empirical laws (like gravity), but by subjective motivations, purposes, and desires.
We cannot meaningfully engage in empirical testing (observe, predict, test, confirm/falsify, repeat) in any field concerning human action as its primary object of study. Since human action itself isn’t causally-structured, but teleologically-propelled, there are no definite predictions we can make about it based on past-observations alone.
With regard to the external world, where empirical analysis does apply, there are constantly-operating mechanisms. This doesn’t work in the case of human action. In physics we can use equations and mathematics to represent constant factors and phenomena which operate indifferently to time. The trajectory of a falling rock will be subject to all of the physical laws and constants that a falling elephant will. The trajectory of an acting human being, based on knowledge and subjective valuations is categorically a different matter.
Since all action is guided by knowledge, and since future-knowledge can never be known with certainty in the present moment, (if it were, it would no longer be “future” knowledge,
but “now” knowledge) no scientific predictions about future action based on the past knowledge of an actor can ever be made.
To observe past behavior, guided by past knowledge, and project this into the future as a prediction,one ignores the fact that all future action will be guided by knowledge which the actor has not yet attained, knowledge which no predictor could ever guess (for if we could consistently and accurately predict what we will know, but do not yet know, we would necessarily already know it).
Seen in this light, it becomes silly and absurd to attempt to engage in empirical science in a discipline like economics, which in the modern mainstream must constantly make these sorts of impossible predictions using such tools as econometrics. The empirical economic scientists are using an altogether incorrect and inappropriate method, treating acting human beings like particles or molecules. Human behavior and action cannot be stuffed into a mathematical formula and crank out any kind of reliable prediction, no matter how sophisticated the equations and regressions are. One who takes data about the past and lumps it into an aggregate can only yield a historical account of past economic relations.Never can one use such aggregates to predict future economic conditions. This entire project is vaguely akin to Ptolemaic astronomy trying to force their math and science to fit the notion of an Earth-centric universe, it will only lead to overly complicated falsehoods.
Human action must be examined with tools which we attain through reflective contemplation of the nature of the kind of entity that we, ourselves, are. We cannot attain new knowledge about future action by looking at past action guided by old knowledge. We must first start with what must be necessarily true, a priori, for action to be possible (the categories of thought/action), and then proceed to apply this structure in analyzing the action of others, even in the complex economic and social interrelations that exist in any modern society.
Epistemological dualism gives one the proper tools to distinguish between that which can be discovered through observation and experimentation, and that which is necessary for action in the first place, and therefore discoverable through pure reflection. The fundamental distinctions made by thinkers such as Ludwig von Mises, Murray Rothbard, Stephan Kinsella, and Hans-Hermann Hoppe have carved the way for a Praxeological epistemology, one that recognizes the fundamental difference between teleological and causal knowledge.
The Praxeological study of human action offers more than just economic truth, but truth regarding the nature of thought, regarding epistemology. With the fundamental distinction made between the a priori and the a posteriori, between the reflective and the empirical, between the teleological and the causal,we are equipped with a vital structure for navigating the social sciences. No longer is economics, in particular, a discipline which aims to employ the methods of the physicists, but one that has its own toolbox and conceptual structure to deal with its own set of problems. Human beings are not automatons whose behavior can be reduced to mathematical formulas, nor is human action subject to experimental empirical science, using the knowledge that guides present action to predict future knowledge and action. Praxeology, the study of human action, is a branch of science in its own right,backed by a philosophically-sound theory of knowledge which constrains and defines its legitimate area of study.