Clemens Lode
January 22, 2022
Apple in front of a mirror showing an apple that was bitten off (source: Shutterstock).


This is an excerpt from the book series Philosophy for Heroes: Knowledge.
[Ontology] and epistemology are simultaneous—what exists and how we know it are the foundation that starts together. And that’s why the very first axiom is “Existence exists, and the act of grasping this implies there is something, and we have the faculty for being aware of it.” And thereafter we shift back and forth, “We have consciousness,” “A is A,” “Existence is independent of consciousness,” “We acquire knowledge by reason,” and so on. [Ontology and epistemology] are completely intertwined. —Leonard Peikoff, Understanding Objectivism [Peikoff, 2012, p. 170]

With ontology, we were able to realize that we can be conscious of reality. With epistemology, we want to discuss how we can be conscious of reality. It is important to note here that “axioms are preconditions of knowledge; they are not the starting points of a deductive development; they are not the foundations from which we infer conclusions à la mathematics. […] If all you know is ‘Existence exists,’ and you sit and stare at that, you will never get any further. Those axioms are the foundations of knowledge, which means they enable us then to look at reality, to have actual experience that we then have to conceptualize, induce, integrate, and so on.” [Peikoff, 2012, p. 283]

Why are ontology and epistemology simultaneous?

Besides ontology, epistemology is a supporting foundation of philosophy and concerns itself with how knowledge can be acquired and validated. In that regard, it is important to note that just because we have started with the axioms (ontology), this does not mean that ontology stands first in a long chain of deductions and conclusions. We have to correct our hierarchical list of philosophical elements and replace it with a structure with mutual dependencies (see Figure 1.1).

Figure 1.1: Ontology and epistemology are not derived from each other, instead they together form the foundation of ethics.
Ontology and epistemology are simultaneous—what exists and how we know it form a foundation of philosophy.

The implications of this insight are far-reaching. If we look at how we get to know something (epistemology) as a corollary from the axioms, we could never find out what our consciousness, our mind, and our will is. These concepts would become something undefined, and we would not be able to recognize other entities with a consciousness as such. Only with other people could we argue that, because they are similar to us, they likewise must have a consciousness. Animal, artificial or alien intelligences would always be beings without consciousness.


Man’s senses are his only direct cognitive contact with reality and, therefore, his only source of information. Without sensory evidence, there can be no concepts; without concepts, there can be no language; without language, there can be no knowledge and no science. —Ayn Rand, Philosophy: Who Needs It

Our perceptual faculty is the filtering, integration, and association of several sense perceptions which were converted to a form usable by our cognition (so-called sense data). For example, if we hold an apple in our hand, we see its color and feel its shape and surface. And if we look at it, our eyes provide us with a pre-processed image of the apple that includes edge-detection using the contrast between the apple and the background. These sense data are combined, resulting in our sense perception of the apple. Sense data is information, converted to a form usable by the cognitive process, about an effect registered by a sense organ (e.g., an eye, a nose, an ear, etc.). A sense organ is an entity that is connected to another entity with cognition, and that can register effects of different intensities of properties.

SENSE ORGAN ·  A sense organ is an entity (e.g., an eye, a nose, an ear, etc.) that is connected to another entity with cognition, and that can register effects of different intensities of properties.
SENSE DATA ·  Sense data is information, converted to a form usable by cognition, about an effect registered by a sensory organ.
SENSE PERCEPTION ·  Our perceptual faculty is the filtering, and association of sense data. This happens automatically with our sensory organs. Further filtering and association of thosesense perceptions happens during the cognitive process (our consciousness).
QUALIA ·  The individual instances of conscious experience of sense data are called qualia.
SELF-REFERENCE (RECURSION) ·  If a statement or a process references itself , it is called recursion. Examples would be “Read the sentence you are now reading again” (recursive statement), two opposing mirrors in which the images mirror until infinity (recursive process), cell division where a new cell is created that divides itself as well (likewise a recursive process), etc.
COGNITION ·  Cognition is the faculty for processing and correcting qualia, generating and applying knowledge, changing preferences, as well as reflecting on the process of cognition itself. The result of the process of cognition is consciousness.
PERCEPTION ·  Perception is the whole process of sense perception combined with cognition.

Which five issues could have a detrimental effect on our objective perception?

To understand the context, it is helpful to look at the whole process of cognition, from the sense data to the knowledge we gain. Fundamentally, we can divide it into seven steps (see Figure 1.2):

Figure 1.2: Process of cognition

  1. Effect on the observer by the entity that is being perceived. Entities affect us independent of our perception. While we say that we look at something, that we are actively taking a look at something, the effect of the entity (e.g., light rays) reaches us without any effort or interference on our part. This is similar to what we have discussed previously in Chapter 1.5, “Ontology.” First, reality exists, then we can become aware of it. Concerning philosophy, this view is the so-called “rationalism.” Ultimately, there is confusion between our ability to actively focus and filter our sense perception, and the passive registering of the effects of other entities. Just because we have the ability to wear “rose-colored glasses” and to see only good in the world, this does not change the world—only our evaluation of it.
  2. Processing of the effect with our senses. The sense data are combined into a complete sense perception. Any processing within our sense organs happens dependent on the different individual sense organs. The same picture or the same sound is processed by the sense organs of different people in different ways (e.g., red-green colorblindness) and correspondingly different sense data is being provided to the process of cognition (consciousness).
  3. Interference of other entities. If other entities affect our sense organs, our sense perception could be distorted. Additional unrelated information from our environment has (noise) to be filtered.
  4. Filtering. Our consciousness is limited; we filter the incoming sense data and focus on a specific part. Because of this necessarily limited perception, we could overestimate or overlook certain sense data. These qualia are by their definition subjective, as the consciousness of every human is unique.
  5. Hallucinations. Our brain could misinterpret or create false sense perceptions. Then we could mistake, for example, dreams or hallucinations induced by sleep deprivation or drugs as objective sense data from the outside. Suffering from schizophrenia, you could even end up misinterpreting your own thoughts as sense data coming from the outside.
  6. Processing of the sense data. With our consciousness having become aware of the sense data as qualia (as subjective experiences), we integrate and categorize them using logic. In this process, errors could happen, be it because of sloppiness, laziness, or because of an erroneous philosophy. For example, with the assumption that “All humans read Philosophy for Heroes (and Max is a human),” the conclusion “Max reads Philosophy for Heroes” would be logically correct, but (unfortunately) the assumption would be wrong with regard to content. On the other hand, the assumption “Readers of Philosophy for Heroes are humans (and Max is a human)” is correct with regard to content, but a conclusion like “Max reads Philosophy for Heroes” would not be necessarily logically correct. Just because he is a human, that does not mean he reads this book.
  7. Reflection. In order to interpret our conscious subjective experiences (qualia), correct errors, and draw conclusions about reality, we have to reflect on the cognitive process. Reflection itself is also part of cognition—we also have to reflect on how we reflect. If we assume that our environment has been conspiring against us, we question everything but our own paranoia. But we would also have to check whether our assumption about our environment is correct. A special case of (missing) reflection is if you are fine with the fact that you never reach a conclusion when using a recursive statement for an argument. With a statement like, “I cannot make statements,” you would never reach a conclusion if you try to rectify it by saying “I cannot make statements except for the statement, ‘I cannot make statements.”’ You could do that for infinity. It is like saying that “something is true because because because …” without ever providing a final argument why it is true.

For the last point, reflection, we have to expand our discussion a little bit. We have now discussed how we can perceive the world and how an individual, subjective experience of reality is created in our consciousness (qualia). At the same time, we have also listed what problems can occur during the process of sense perception and cognition, i.e., how our view of the world can be distorted. Ultimately, it looks as if we had indeed one experience of the world but could (with the exception of the axioms, the foundations of knowledge) not be sure that what we perceive really corresponds to the real world.

But what is the qualitative difference compared to our discussion of axioms? We know that something has had an effect on us, we just do not know how, what, and from where exactly. It is like a murder-mystery game, where we have to track down the effect step by step to its original source; we have to reflect on the whole process of cognition. If we know that our conversation partner lies, we can process the information we get from him in a way so that the lie no longer has power over us. Or when we look at a spoon in a glass of water, it looks as if it is bent. But our experience or our knowledge about light refraction tells us that it is not the spoon but the light that is “bent.” So, the more we know about what distorts our cognition, the more our insights relate to reality.

Ultimately, reflection is a loop, because new knowledge might also shine new light on our existing knowledge of the workings of our own cognition, which again could change our perception of the world, which again might provide us new insights into our cognition, and so forth. While we are not born with knowledge about the world or our cognition, we do not have to know how our cognition works in order for it to work. Our mind has the automatic ability to learn and to use basic logic, i.e., to associate two different sense perceptions to form a single conscious experience. When we see a barking dog, we can quickly learn that it really is the dog that is barking by combining our visual with our auditory sense data.

Obviously, we can spin it further at this point and argue that we could be wrong in the assessment of our cognitive abilities and that we are unable to check them because our cognitive abilities are defective. This could end up with us having a blind spot in regard to certain aspects of reality, especially if we add outside manipulation. We cannot easily refute thought experiments where we are nothing but brains in a laboratory of a mad scientist, or more generally, where the universe actively conspires against us and deliberately feeds us wrong information into our mind.

Did you know? The idea that reality is an illusion is a popular notion, going back to “Plato’s cave”—an allegory by Plato to show that we could mistake what we see as mere shadows of what reality really is. It is also a central motif of Matrix, a movie that challenges the viewer to ask whether we live in a computer simulation. The point is that we can always find out—eventually. In all cases, it is impossible to shield the inside world from the “jitter” of the outside world without leaving evidence. Read more in Philosophy for Heroes: Act.

The Limits of Perception

Man is neither infallible nor omniscient; if he were, a discipline such as epistemology—the theory of knowledge—would not be necessary nor possible: his knowledge would be automatic, unquestionable, and total. —Ayn Rand, Introduction to Objectivist Epistemology [cf. Rand et al., 1990, p. 78]

What, if any, effect on us must remain hidden?

For now, we assume we are living in a universe that does not try to actively deceive us. With this condition, can we perceive reality objectively, as it is, or are we principally limited? Objective perception relates to the faculty to perceive any properties of any entity in principle, independent of one’s own individual sense organs. For this, we need cognition, the faculty of processing and correcting sense perceptions, and generating and applying knowledge. Without cognition, the following two objections could be raised:

  • Our sense organs themselves could be inadequate to perceive certain aspects of reality.
  • Certain identities could categorically elude sense perception, or besides their identities which we perceive, entities could possess a deeper “identity-in-itself” which we could not perceive.

Let us first look at the question whether our senses might be so limited that we perhaps fundamentally cannot perceive a part of reality. What about infrared or ultraviolet radiation, ultrasound, electromagnetism, infrasound, or Earth’s magnetic field, for example? We lack the necessary sense organs for these sources of information. In contrast, a closed, non-transparent box is no obstacle for a dolphin: while a direct view of the contents is hidden from its eyes, its brain extends its spatial perception of the world by means of sonar, and the box becomes virtually transparent. [cf. White, 2007, p. 26]

In spite of our limitations, we can, however, make objective perceptions. As discussed above, perception consists of the sense perception of the actual sense data (the interaction of a signal with one’s sense organs) as well as the cognitive processing with one’s mind. We are thus not limited to direct effects on our senses, but we can also incorporate indirect effects into our thoughts. For example, we could construct devices (e.g., a camera with color translation, a compass, or special microphones) which would allow us to recognize these signals with one of our other senses, or we could communicate with animals that possess these sense organs (e.g., with dogs, owing to their sense of smell). So, any entity can be perceived as it interacts by definition with other entities. And ultimately, given enough time, as effects result in yet other effects, everything is interrelated with everything else.

We can overcome physical limitations of our senses through the use of our minds and scientific instruments. No effect on us necessarily needs to remain hidden.

The Range of Perception

Now, what’s the difference between an invisible, incorporeal, floating dragon who spits heatless fire and no dragon at all? If there’s no way to disprove my contention, no conceivable experiment that would count against it, what does it mean to say that my dragon exists? —Carl Sagan, The Demon-Haunted World: Science as a Candle in the Dark [Sagan, 1997, p. 171]

How should we deal with arbitrary claims?

Assume for a moment that there was something that did not interact with the entities in our reality, and thus was not recognizable through observation, either directly or indirectly (i.e., through its reaction with other entities, such as machines). To what extent should we attribute this “something” to reality? If it cannot react with anything, then it can have no effect. And without an effect, the entity has no properties. It could “exist” in a formal sense but would have no identity. Such a “something” would have no connection to reality. We could classify this “something” in the same category as invisible, weightless dragons.

The argument remains that such entities would possibly possess properties of some kind that we simply have not yet discovered. The problem here is that, theoretically, there could be an infinite number of such entities. To what extent we attach a value to these entities is a question of ethics. In the first place, a life-oriented philosophy denies the existence of anything for which there is no evidence, since we cannot take into consideration all these possible entities with every decision we make. But the fact that we are limited is not the reason we, in our actions, deny or ignore arbitrary claims about the existence of undiscovered entities. We are ignoring such claims because they are not proper claims. Just because you claim something, it does not mean that there is any merit to it, or that we have to actively ignore it in our decisions. We consider only claims or arguments that have some connection to reality.

Immanuel Kant went one step further in Prolegomena. He denied that people have the capability of recognizing the “things in themselves:”

There are things given to us as objects of our senses existing outside of us yet we know nothing of them as they may be in themselves, but are acquinted only with their appearances, i.e., with the representations that they produce in us because they affect our senses. —Immanuel Kant, Prolegomena to Any Future Metaphysics: That Will Be Able to Come Forward as Science [Kant and Hatfield, 2004, pp. 40–41]

The problem of the “things in themselves” is an extension of the problem of the “invisible dragon.” He understood it as everything of an entity which could not be perceived in principle. In practice, this would mean that every perceivable entity was or could be linked to a non-perceivable entity. But these “things in themselves” would have no properties and thus also no identity and according to their definition would not exist.

In the Middle Ages, people wrote “Here be dragons” on all places of maps outside of their geographical knowledge. Today, such signs still exist, despite having satellites and the Internet. But it is the maps of the mind that still carry such signs. People say that everything in the world has already been discovered and that there is nothing more to do for explorers and adventurers. I point them to those mental maps that are still filled, yes, with “dragons”—but more importantly, also with opportunities.

The universe is probably littered with the one-planet graves of cultures which made the sensible economic decision that there’s no good reason to go into space—each discovered, studied, and remembered by the ones who made the irrational decision. —Randall Munroe, Xkcd Munroe [2010]
Arbitrary claims can be ignored. Just because you can make the claim does not mean that it has any connection to reality that needs to be considered.

It lies with adventurers and researchers to take on the risk of traveling into the unknown, to discover and map out these unfamiliar worlds; the burden of proof rests on them, but so, too, does the glory of their possible discovery. For them, their pursuit of knowledge is an ethical question. But while they do not know what is at their goal, they know there is something. Sure, there is the possibility of finding a treasure island, but they do not travel there exclusively to prove or disprove that unsubstantiated claim. Even if all they find is the sea, their discovery would still be worth something, namely filling the map, showing others so they do not have to search for themselves.

So, objective perception does not mean that we would possess sense organs that automatically supply us with “correct” information from the environment. Rather, we are in the position to extract objective information about reality from the environment, with or without means of assistance, but in any case with the assistance of the mind. Objective perception means that we can draw conclusions about the causes of everything that interacts with our bodies (more precisely, our senses). When we see a ray of light, we cannot automatically know its source. We need a series of subsequent light rays in order to construct a three-dimensional image of our surroundings. In addition, we still require conscious knowledge about possible optical illusions and hallucinations of the brain. If we have correctly processed all this knowledge, we obtain an objective picture of reality. Here it should again be emphasized what we previously have established: without objective perception, the logical discussion of perception itself is ultimately not possible in the first place. To claim that our perception is subjective would again be a fallacy of the stolen concept. If we had no possibility of perceiving the world, we could acquire no knowledge, including knowledge of the axioms.


Ontology and epistemology are simultaneous—what exists and how we know it form a foundation of philosophy.
We can overcome physical limitations of our senses through the use of our minds and scientific instruments. No effect on us necessarily needs to remain hidden.
Arbitrary claims can be ignored. Just because you can make the claim does not mean that it has any connection to reality that needs to be considered.

Related Books and Services

Recommended Further Reading

Coffee standing on a paper with diagrams and the text Concepts (source: Shutterstock).
January 22, 2022


Concepts are abstractions that permit us a description of reality and allow us to form compact units of information from many different origins.

About the Author

Clemens Lode

Hello! My name is Clemens and I am based in Düsseldorf, Germany. I’m an author of books on philosophy, science, and project management, and coach people to publish their books and improve their approach to leadership.

I like visiting the gym, learning to sing, observing animals, and creating videos on science and philosophy. I enjoy learning from nature and love the idea of optimizing systems.

In my youth, I was an active chess player reaching the national championship in Germany, and an active pen&paper player leading groups of adventurers on mental journeys. These activities align with my calm approach to moderating meetings, leading meetups, and focusing on details. My personality type in socionics is IEE/ENFp.

Clemens Lode

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Philosophy is the study of existence, knowledge, values, language, and related topics that have challenged both ordinary and great thinkers throughout human history.


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