The Problems of Philosophy

1. Reality is not always as it appears; our senses can deceive us.

In daily life, we assume as certain many things which, on a closer scrutiny, are found to be so full of apparent contradictions that only a great amount of thought enables us to know what it is that we really may believe.

Appearance vs. Reality. What we perceive through our senses is not necessarily an accurate representation of reality. The color, shape, and texture of objects can change depending on our perspective, lighting, and other factors. For example, a table may appear to be different colors from different angles, or smooth to the naked eye but rough under a microscope.

• Our senses provide us with "sense-data," which are our immediate experiences, but these are not the same as the "physical objects" that we believe cause them.
• The distinction between appearance and reality is a fundamental problem in philosophy, prompting us to question the nature of the world around us.

Subjectivity of Perception. Our sensory experiences are subjective and influenced by our individual perspectives. What one person sees, feels, or hears may not be exactly the same as what another person experiences. This subjectivity raises questions about the reliability of our senses as a source of objective knowledge.

• A color-blind person will perceive colors differently than someone with normal vision.
• The same object can appear different to different people based on their position and the lighting conditions.

Need for Critical Thinking. The discrepancies between appearance and reality highlight the need for critical thinking and careful analysis. We cannot simply rely on our immediate sensory experiences to understand the world; we must also consider the limitations of our senses and the possibility of deception.

• Philosophy encourages us to question our assumptions and to explore the underlying nature of reality.
• By examining the contradictions and ambiguities in our everyday experiences, we can gain a deeper understanding of the world.

2. The existence of matter is a reasonable, though unprovable, assumption.

No logical absurdity results from the hypothesis that the world consists of myself and my thoughts and feelings and sensations, and that everything else is mere fancy.

Solipsism and the External World. It is logically possible that the only thing that exists is our own mind and its experiences, and that everything else is a dream or illusion. This idea, known as solipsism, cannot be definitively disproven. However, there is no reason to believe it is true.

• The possibility of solipsism raises the question of whether there is an external world that exists independently of our minds.
• If we cannot be sure of the existence of objects, we cannot be sure of the existence of other people's bodies, and therefore, their minds.

Simplicity and Common Sense. The belief in an independent external world is a simpler and more natural explanation for our experiences than the idea that everything is a dream. It is more straightforward to assume that objects exist whether we perceive them or not.

• If a cat appears in one part of the room and then another, it is simpler to assume that it moved rather than that it ceased to exist and then reappeared.
• The behavior of sense-data, such as the cat's hunger, is more easily explained by the existence of a real cat than by mere changes in patches of color.

Instinctive Belief. Our belief in an independent external world is an instinctive belief that arises as soon as we begin to reflect. We are naturally inclined to believe that there are objects that exist independently of our perception.

• This belief is not based on logical proof but on a deep-seated intuition.
• While we cannot prove the existence of matter, it is a reasonable assumption that simplifies and systematizes our understanding of our experiences.

3. Matter, as understood by science, is fundamentally different from our sensory experiences.

When it is said that light is waves, what is really meant is that waves are the physical cause of our sensations of light.

Scientific View of Matter. Physical science reduces all natural phenomena to motions, such as wave-motions. Light, heat, and sound are all due to wave-motions that travel from the source to the observer.

• Science describes matter in terms of position in space and the power of motion, but it does not describe the qualities that we experience through our senses.
• The light we see is not the same as the wave-motion that causes it; the wave-motion is the physical cause of our sensation of light.

Physical Space vs. Private Space. The space in which physical objects exist is not the same as the space we perceive through sight or touch. The space of science is neutral between touch and sight, and it is public, while our perceived space is private.

• Different people see the same object as having different shapes, depending on their point of view.
• The real shape of an object, which is what concerns science, must be in a real space that is different from our private spaces.

Unknown Intrinsic Nature. While we can know the relations of physical objects in physical space, we cannot know their intrinsic nature through our senses. The qualities that we perceive, such as color and sound, are not inherent in the objects themselves but are caused by the interaction between the objects and our senses.

• The color we see depends on the light waves that strike our eyes, not on an inherent property of the object.
• The real nature of matter remains unknown to us, at least through the means of our senses.

4. Idealism, the view that reality is fundamentally mental, is a flawed concept.

The act is undoubtedly in the mind; hence, when we are thinking of the act, we readily assent to the view that ideas must be in the mind.

Idealism Defined. Idealism is the doctrine that whatever exists, or at least whatever can be known to exist, must be in some sense mental. This view is often based on the idea that whatever we can think of is an idea in our minds.

• Idealists argue that matter is either a collection of ideas or a collection of rudimentary minds.
• Berkeley, a prominent idealist, argued that the "real" table is an idea in the mind of God.

Fallacy of "Idea". The word "idea" is used ambiguously, leading to confusion. An idea can refer to the thing we are aware of (e.g., the color of a table) or to the act of being aware of it.

• Berkeley's argument that the tree must be in our minds confuses the thought of the tree with the tree itself.
• The act of apprehension is mental, but the thing apprehended is not necessarily mental.

Act vs. Object. The distinction between the act of apprehension and the object apprehended is crucial. The act is undoubtedly in the mind, but the object is not necessarily mental.

• The color we see is not in the mind of the perceiver, but depends on the relation of our sense organs to the physical object.
• The faculty of being acquainted with things other than itself is the main characteristic of a mind.

Knowledge and Reality. The argument that we cannot know that anything exists which we do not know is false. We can know that something exists by description, even if we are not acquainted with it.

• We can know that the Emperor of China exists, even if we have never met him.
• The fact that we can think of something does not mean that it must be mental.

5. Knowledge comes in two forms: acquaintance and description.

All our knowledge, both knowledge of things and knowledge of truths, rests upon acquaintance as its foundation.

Acquaintance Defined. Knowledge by acquaintance is direct awareness of something, without any intermediary process of inference or knowledge of truths. We are acquainted with sense-data, such as colors, sounds, and textures.

• When we see a color, we are immediately aware of it, and no further knowledge of it is possible.
• We are also acquainted with our own thoughts, feelings, and desires through introspection.

Description Defined. Knowledge by description is knowledge of an object through a phrase that identifies it, such as "the so-and-so." We know that there is an object that fits the description, but we are not directly acquainted with it.

• We know that the man with the iron mask existed, but we do not know who he was.
• We know that the candidate who gets the most votes will be elected, but we may not know which candidate that is.

Descriptions and Particulars. Common words, even proper names, are often really descriptions. The thought in the mind of a person using a proper name can usually only be expressed explicitly by replacing the name with a description.

• When we make a statement about Bismarck, we are not directly acquainted with him, but we have a description of him in mind.
• All names of places involve descriptions that start from some particulars with which we are acquainted.

Fundamental Principle. Every proposition we can understand must be composed wholly of constituents with which we are acquainted. This principle is fundamental to our understanding of knowledge.

• When we make a statement about Julius Caesar, we have in mind some description of him, not the man himself.
• Knowledge by description enables us to pass beyond the limits of our private experience.

6. Induction, though essential, cannot be proven by experience.

The only reason for believing that the laws of motion will remain in operation is that they have operated hitherto, so far as our knowledge of the past enables us to judge.

The Problem of Induction. Induction is the process of inferring general laws from particular instances. We believe that the sun will rise tomorrow because it has always risen in the past.

• The problem is that no number of past instances can logically guarantee that the same pattern will continue in the future.
• The belief in the uniformity of nature, that everything is an instance of a general law, is itself based on induction.

Instinct vs. Reason. Our instincts cause us to expect that the future will resemble the past, but these expectations are not always reliable. We must distinguish between the fact that past uniformities cause expectations and the question of whether there is any reasonable ground for these expectations.

• Animals also have expectations based on past experiences, but these expectations can be misleading.
• The chicken that has been fed every day may be surprised when its neck is wrung.

The Inductive Principle. The inductive principle states that when two things have been found often together and never apart, the occurrence of one gives good ground for expecting the other. This principle has two parts:
- The greater the number of cases of association, the greater the probability of a fresh association.
- A sufficient number of cases will make the probability of a fresh association nearly a certainty.

Limitations of Experience. The inductive principle cannot be proven by experience, because all arguments based on experience assume the inductive principle. We cannot use experience to prove the inductive principle without begging the question.

• We must either accept the inductive principle on the ground of its intrinsic evidence or forgo all justification of our expectations about the future.
• All knowledge that tells us something about what is not experienced is based on this principle.

7. A priori knowledge, including logic and ethics, is independent of experience.

In fact, the truth of the principle is impossible to doubt, and its obviousness is so great that at first sight it seems almost trivial.

A Priori Knowledge Defined. A priori knowledge is knowledge that is independent of experience. It is not derived from observation or sensory data but is known through reason alone.

• Logical principles, such as the law of contradiction, are examples of a priori knowledge.
• Ethical principles, such as the belief that happiness is more desirable than misery, are also a priori.

Empiricism vs. Rationalism. Empiricists believe that all knowledge is derived from experience, while rationalists believe that there are innate ideas and principles that we know independently of experience.

• The empiricists, such as Locke, Berkeley, and Hume, believed that all knowledge comes from sensory experience.
• The rationalists, such as Descartes and Leibniz, believed in innate ideas and principles.

Logical Principles. Logical principles, such as the principle that what follows from a true premise is true, are self-evident and cannot be proven by experience. These principles are necessary for any argument or proof.

• The "Laws of Thought" (identity, contradiction, excluded middle) are examples of self-evident logical principles.
• These principles are not merely laws of thought but also laws of how things behave.

A Priori vs. Empirical. A priori knowledge is not the same as empirical knowledge. Empirical knowledge is based on experience, while a priori knowledge is based on reason.

• All knowledge that asserts existence is empirical, while a priori knowledge is hypothetical.
• A priori knowledge gives connections among things that exist or may exist, but not actual existence.

Mathematics and Ethics. Pure mathematics, like logic, is a priori. We can know that two and two are four without needing to experience it repeatedly. Ethical values are also known a priori.

• We judge that happiness is more desirable than misery, and this judgment is not based on experience.
• A priori knowledge is elicited by experience but not proven by it.

8. A priori knowledge concerns universals, not particulars.

The fact seems to be that all our a priori knowledge is concerned with entities which do not, properly speaking, exist, either in the mental or in the physical world.

Universals Defined. Universals are general ideas, such as whiteness, diversity, and brotherhood. They are opposed to particulars, which are the specific things given in sensation.

• Every complete sentence must contain at least one word that stands for a universal.
• Universals are not particular things but are shared by many particulars.

Qualities and Relations. Adjectives and common nouns express qualities or properties of single things, while prepositions and verbs express relations between two or more things.

• The neglect of prepositions and verbs has led to the belief that every proposition attributes a property to a single thing.
• Relations are just as real as qualities and are essential for understanding the world.

Universals and the Mind. Universals are not merely mental constructs. They have a being that is independent of our minds.

• The relation "north of" exists independently of our knowledge of it.
• Universals subsist, while particulars exist.

A Priori Knowledge and Universals. All a priori knowledge is concerned with the relations of universals. When we know that two and two are four, we are stating a relation between the universals "two" and "four."

• A priori knowledge does not require knowledge of particular instances but only of the relations between universals.
• We can know general propositions even when we do not know a single instance of them.

Limitations of A Priori Knowledge. A priori knowledge does not tell us anything about the existence of particular things. It only tells us about the relations of universals.

• We know a priori that two things and two other things make four things, but we do not know a priori that Brown and Jones and Robinson and Smith are four.
• All applications of a priori knowledge to actual particulars involve experience.

9. Universals subsist, while particulars exist.

The world of universals, therefore, may also be described as the world of being.

Existence vs. Subsistence. Things that exist are in time, meaning we can point to a time at which they exist. Thoughts, feelings, minds, and physical objects exist.

• Universals, on the other hand, do not exist in this sense. They are not in time.
• We say that universals subsist or have being, where "being" is opposed to "existence" as being timeless.

The World of Being. The world of universals is unchangeable, rigid, exact, and delightful to the mathematician and the logician. It is the world of being.

• The world of existence is fleeting, vague, without sharp boundaries, and contains all thoughts, feelings, and physical objects.
• Both worlds are real and important to the metaphysician.

Relations and Universals. Relations, such as "north of," do not exist in the same way that Edinburgh and London exist. They are not in space or time, but they are something.

• Relations are universals, and they are not dependent on thought.
• The relation "north of" would exist even if there were no minds in the universe.

Universals and Thoughts. Universals are not thoughts, although when known, they are the objects of thoughts. The act of thinking of whiteness is different from whiteness itself.

• If whiteness were the thought, no two different men could think of it, and no one man could think of it twice.
• That which many different thoughts of whiteness have in common is their object, and this object is different from all of them.

The Importance of Both Worlds. Both the world of being and the world of existence are important. We must consider their relations.

• The world of being is the realm of universals, while the world of existence is the realm of particulars.
• Both worlds have the same claim on our impartial attention.

10. Intuitive knowledge is the foundation of all other knowledge.

Self-evidence, however, is not confined to those among general principles which are incapable of proof.

Intuitive Knowledge Defined. Intuitive knowledge is immediate knowledge that is not derived from inference or reasoning. It is the foundation upon which all other knowledge is built.

• Self-evident truths, such as the law of contradiction, are examples of intuitive knowledge.
• Truths of perception, which are derived from sensation, are also intuitive.

Self-Evidence and Proof. Some truths are self-evident and do not require proof. We can be driven back from point to point until we reach a principle that is luminously evident and not capable of being deduced from anything more evident.

• The inductive principle is an example of a principle that is constantly used but cannot be proven.
• Particular instances of general principles are often more evident than the general principle itself.

Truths of Perception. Truths of perception are derived from our senses. They can be of two kinds:
- Those that simply assert the existence of a sense-datum.
- Those that analyze a complex sense-datum and assert a relation between its constituents.

Judgements of Memory. Judgements of memory are another class of intuitive judgements. They are based on having immediately before the mind an object that is recognized as past.

• Memory is not constituted by the image of the object but by the immediate awareness of the past object.
• Without memory, we would not know that there ever was a past.

Degrees of Self-Evidence. Self-evidence has degrees, ranging from absolute certainty to an almost imperceptible faintness. The trustworthiness of our intuitive judgements corresponds to the degree of their self-evidence.

• Truths of perception and some logical principles have the highest degree of self-evidence.
• Memories have a diminishing self-evidence as they become remoter and fainter.

11. Truth is a correspondence between belief and fact.

Thus a belief is true when it corresponds to a certain associated complex, and false when it does not.

Truth and Falsehood. Unlike knowledge of things, knowledge of truths has an opposite, namely error. We can believe what is false as well as what is true.

• The question of how to distinguish true beliefs from false ones is a difficult one.
• We must first decide what we mean by truth and falsehood before we can determine how to know what is true.

Requisites of a Theory of Truth. Any theory of truth must fulfill three conditions:
- It must allow for the possibility of falsehood.
- It must make truth a property of beliefs.
- It must make truth dependent on the relation of beliefs to outside things.

Coherence Theory Rejected. The theory that truth consists in coherence is inadequate because there is no reason to suppose that only one coherent body of beliefs is possible.

• There may be multiple coherent systems that are mutually incompatible.
• Coherence presupposes the truth of the laws of logic, which cannot be established by coherence.

Correspondence Theory Adopted. Truth consists in a correspondence between belief and fact. A belief is true when it corresponds to a certain associated complex, and false when it does not.

• The truth of a belief depends on something outside the belief itself.
• If I believe that Charles I died on the scaffold, I believe truly because of an historical event, not because of any intrinsic quality of my belief.

Belief as a Relation. Belief is a relation between a mind and several objects, not a relation between a mind and a single object. When Othello believes that Desdemona loves Cassio, the relation of believing connects Othello, Desdemona, loving, and Cassio.

• The relation of judging has a "sense" or "direction" that puts its objects in a certain order.
• The relation of believing is the cement that unites the subject and the objects into a complex whole.

Truth and Correspondence. A belief is true when there is a corresponding complex unity composed only of the objects of the belief. If Othello believes truly that Desdemona loves Cassio, then there is a complex unity, "Desdemona's love for Cassio."

• If a belief is false, there is no such complex unity composed only of the objects of the belief.
• Minds do not create truth or falsehood; they create beliefs, but the truth of a belief depends on a fact that does not involve the mind.

12. Philosophical knowledge has limits, and metaphysics cannot prove everything.

It would seem that knowledge concerning the universe as a whole is not to be obtained by metaphysics, and that the proposed proofs that, in virtue of the laws of logic such and such things must exist and such and such others cannot, are not capable of surviving a critical scrutiny.

Metaphysical Claims. Many philosophers claim to be able to prove, by a priori metaphysical reasoning, such things as the fundamental dogmas of religion, the essential rationality of the universe, and the unreality of matter.

• Hegel believed that everything short of the Whole is incomplete and that the universe forms a single harmonious system.
• He believed that by examining any one piece of reality, we can deduce the nature of the whole.

Hegel's System. Hegel's system is based on the idea that what is incomplete must need the support of other things before it can exist. He believed that every idea passes into its opposite, and that the synthesis of these opposites leads to a more complete idea.

• He believed that the Absolute Idea is adequate to describe Absolute Reality.
• He believed that space, time, matter, and evil are due to our fragmentary view of the universe.

Critique of Hegel. The fundamental tenet of Hegel's system is that what is incomplete must be not self-subsistent. This view turns on the notion of the "nature" of a thing, which is defined as "all the truths about the thing."

• A truth about a thing is not part of the thing itself, although it is part of the "nature" of the thing.
• We can have knowledge of a thing by acquaintance without knowing all of its relations.

Limits of Metaphysics. We cannot prove that the universe as a whole forms a single harmonious system. We cannot prove the unreality of space, time, matter, and evil.

• We are left to the piecemeal investigation of the world and cannot know the characters of those parts of the universe that are remote from our experience.
• The tendency of modern thought is to show that supposed contradictions are illusory and that very little can be proven a priori.

Space and Time. Space and time appear to be infinite in extent and infinitely divisible. It is difficult to believe that we will reach a last point or a first or last time.

• The supposed contradictions in space and time are illusory.
• We cannot prove a priori that space and time are finite or infinite.

Last updated: April 27, 2025