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Philosophy and the Problem of Knowledge

Prof Frederick V. Rael has been teaching for almost 20 years in various local colleges and universities in the Philippines.

Read on to learn four important perspectives on the philosophical problem of knowledge.

Read on to learn four important perspectives on the philosophical problem of knowledge.

How Do We Know What We Know?

Consider this fictional scenario of Juan and Pedro to begin considering the problem of knowledge. While they wander around, Juan starts a random conversation.

Juan: I’m thinking of something that looks like a human but has wings of a bird. I don’t know what to call it.

Pedro: You know Juan, humans, and birds are two different breeds of species. Maybe you’re just thinking of fictional creatures like an angel, cupid, or Icarus of the Greek Mythology?

Juan: No. This is new. And I want to call it “Birdman.”

Pedro: Is there such a creature? It is not even a word. You’re imagining things.

Juan: It’s my idea, it’s my word. Go invent your own.

Juan and Pedro are faced again with another challenging philosophical query, which is the problem of knowledge. First of all, knowledge is something that exists in our minds. It also pertains to our awareness, understanding, or recognition of anything outside of us or those things within our environment. Although it is as simple as it appears, in philosophy, the problem of knowledge is a complex and debatable one.

Plato advises us that knowledge is different from true belief. Not all that we know is knowledge. Most of them may be beliefs or collected ideas that are unverifiable or invalid perceptions. The main issues in proceeding with the said topic in philosophy are its source and its validity.

Specifically, Juan and Pedro are trying to answer the questions, “How do we acquire what we know?” and “How would we know that our ideas are valid?”

Rene Descartes’ Discovery of Method was conceptualized in 1619 through a “blinding flash” of insight (Jacobus, 1994)

Various Perspectives on Knowledge

The following sections present four major perspectives on understanding the problem of knowledge. These perspectives are idealism, materialism, skepticism, and the known and the unknown.


One way to look at it is through the perspective of idealism. Some philosophers claim that the existence of the external reality or that dimension that goes beyond the subject is not real without the human mind. Everything we know becomes real because of the capability of the human mind to construct reality.

In other words, an object is unknown until the human mind recognizes it. Out of necessity, our mind tends to create something useful like a new device, technology, or instrument.

As proofs, Rene Descartes’ Discovery of Method was conceptualized in 1619 through a “blinding flash” of insight (Jacobus, 1994) while E=mc2 of Albert Einstein popped out of nowhere when he was staring at nothing (Goldstein, 2007).

Idealists argue that the human mind has the enormous capability of producing something out of nothing. Thus, the ultimate source of knowledge is the human mind that creates a valid or an ideal reality.


On the opposite side, materialists argue that “Nothing comes from nothing.” Parmenides, an Ancient philosopher, who explicates that nothing in the material world emerges from the human mind (Arieti, 2005). External reality pre-exists and it is our task to discover what is in it. In doing so, we can know something through our five senses by perceiving objects or organisms around us.

In most cases, we capture some of the elements of external reality through our senses to create our own, a new one. We also explore the sensory world to collect ideas and formulate our own beliefs. As in the case of Juan, he sees a bird and a man in the material world, then he creates a new creature in his mind, a birdman. But, the validity of this entity is questionable due to its unverifiable material components.


One of the famous skeptics David Hume (1711-1776) offers a third perspective in this philosophical quest. His theory that goes with the saying, “What is may not be,” says it all.

Hume convinces us that what appears to be real may be false. Whether we like it or not, the human mind collects ideas from the material reality, which he doubts as true. He considers these ideas as mostly false since the human mind merely constructs the scattered and unrelated ideas into reality. It is forced to makes sense of the world around us through cognitive operations.

Though Hume believes in the material world, for him, such a reality poses uncertainty as well. He warns us that the things that we perceive in the natural environment such as a rock or a tree may only be an impression of that object. The rock is merely sending some form of a signal to our mind that creates an impression or in Hume’s parlance, an imagination.

We perceive a blurred reality but the mind tries to make sense out of it for our convenience. But, the thing in itself cannot be known whether we use our senses or our mind. The essence of that reality will always be uncertain. This leads Hume to deduce that we must doubt everything and what persists is the uncertainty of things.

But how did Hume live a life full of meaning? He argues that we are constrained to believe that there is a true reality outside us for our own sake. We must believe in food, cars, or anything that would help us in making sense of this world. Skeptics even consider natural laws such as the law of gravity, fresh air, and others as mental constructs that may not characterize the true essence of reality.

With the distrustful tendency, Hume’s skepticism is a suitable perspective for crime investigators, scientists, and for housewives who always doubt the fidelity of their husbands.

Kant developed two varieties of knowledge, a priori knowledge (ideas from pure reasoning) and a posteriori knowledge (ideas from experience)

The Known and The Unknown

Perhaps, you are as confused as I am while going through the propositions of idealism, materialism, and skepticism. Pursuing this quest formulates more questions than clarifications since the topic is highly contested.

Fortunately, Immanuel Kant (1724-1804), a great philosopher during the enlightenment period, offered a resolution to settle the problem of knowledge. There must be something true in this life, he argues. He refuses to accept the theory of Hume since it promotes nihilism or nothingness.

In his philosophical investigation, Kant developed two varieties of knowledge, a priori knowledge (ideas from pure reasoning) and a posteriori knowledge (ideas from experience) (Greenberg, 2010). In other words, pure reasoning is the innate ability of the human mind to produce ideas.

He considers some of these ideas as valid or knowledge such as logic, mathematics, equations, and scientific theories. These ideas are unquestionably true since they can be used to build bridges, buildings, and many physical structures that comprised material reality.

On the one hand, things that are derived from the environment through the five senses are also a valid reality. Physical elements such as colors, textures, sounds, and the like are equally real since they represent the actual material phenomenon. Objects in the natural environment can’t exist without these fundamental components.

Kant further argues that there are things in this world that can be known particularly those that can be observed in the world of phenomenon (material reality). Animals, plants, planets, and other such things can be studied or analyzed because they exist in material reality. However, there are limits to what we can know especially those ideas that emanate from the world of noumena (world of the unknown).

Indeed, Kant has placed some of the things that we might know but we can’t whatever we do in the world of the unknown. For him, ideas like a ghost, soul, god, and other such concepts can’t be verified by mathematics and science. They only exist in the world of the unknown. Kant concluded that these things can only be discerned by faith alone, not by reason.

Birdman: To Be or Not To Be

To decide on the debate of the two, Juan is an idealist while Pedro is a materialist. Juan believes in something that may exist only in his mind while Pedro is already convinced of what is known consisting of the material bird and the material man.

For Hume, both of their claims may be true or false and nobody knows which of them is carrying the truth. For Kant, Pedro is correct to assume that there is no such thing as a birdman in the world of phenomena. However, Juan may continue his quest for creating such a creature that may become a reality in the future, a birdman.

This concept may not exist today, but Kant promises us that anything unknown today may be invented or discovered tomorrow. Just have faith in it.


Arieti, J. (2005). Philosophy in the Ancient World: An Introduction.

Goldstein, G. (2007). Life Without Limits: Powerful Truths That Bring Hope and Meaning.

Greenberg, R. (2010). Kant's Theory of A Priori Knowledge.

Jacobus, L. (1994). A World of Ideas: Essential Readings For College Writers.

Hume, D. (2019). An Enquiry Concerning Human Understanding.

This content is accurate and true to the best of the author’s knowledge and is not meant to substitute for formal and individualized advice from a qualified professional.

© 2020 Frederick V Rael


Frederick V Rael (author) from Philippines on August 18, 2020:

thanks a lot. I fully appreciate the comments.

JourneyHolm on August 18, 2020:

Excellent article. Well done.