Epistemology: Empiricism - Hume (1711-1776)

David Hume pushed the principles of Locke and Berkeley to their logical conclusions. Hume's most important work is Treatise on Human Nature. He also enlarged upon certain portions of this work in other publications such as An Inquiry Concerning the Principles of Morals and the Dialogues concerning Natural Religion.

Hume spoke of matters of fact (synthetic ideas) and relations of ideas (analytic ideas). Hume contended that our knowledge of "facts" about the world is based on experience (That "Some birds are yellow" as we will see in one moment). These types of claims about the world are what Hume called "matters of fact." On the other hand, judgments, statements, or propositions that are true or false by definition are not fact but they are "relations of ideas" (That "all bachelors are unmarried" as we will also see in one moment).

Hume posited that propositions used by rationalists as models for knowledge, such as "a whole is always greater than any one of its parts" and "triangles have three sides" are simply matters of definition. This type of "knowledge" does not provide us with real knowledge other than the meaning of certain terms. As long s we understand the meaning of a certain term we can analyze it and we can do so without learning anything about whether there is anything in the world that the term describes. Relations of ideas statements that identify characteristics already implicit in the meaning of a concept or object are called analytic statements. Examples of this type of statement are "all bodies take up some space" or "bachelors are unmarried males". True analytic statements are those in which the predicate is contained within the subject. In the statement "bachelors are unmarried" the term "unmarried" is the predicate and the term "bachelors" is the subject. If you try to deny this proposition or any proposition like it you contradict yourself.

Synthetic propositions stand in contrast to analytic propositions. Synthetic propositions are those in which the predicate is not part of the meaning of definition of a thing. For example, to say that some birds are yellow is to say something about birds, which are not contained within the definition of what it is that makes a bird a bird. In an analytic statement while "unmarriedness" (so to speak) is the very element that defines a "bachelor" in a synthetic statement "yellowness" is not part of that which defines a bird. By saying that a bird is yellow we add a new bit of information, which we could not know simply by knowing that something is a bird. In other words we appeal to experience. In this sense we combine or synthesize two ideas. One of those ideas, "yellow", is not already implicit within the meaning of the other, "bird." In other words, synthetic propositions are statements in which the predicate IS NOT contained within the subject and if we deny such a "matter of fact" proposition, by saying for example "It is not the case that some birds are yellow", we do not necessarily contradict ourselves.

Hume maintains that there is an important distinction to be made between analytic statements and synthetic statements and the difference between a priori statements and a posteriori statements. The difference between a priori statements and a posteriori statements lies within the matter of whether you have to rely on experience to determine whether the proposition is true or false. In other words, the distinction between a priori and a posteriori statements is experience centered. According to Hume, this is not the case with the distinction between analytic statements and synthetic statements. The distinction between these two lies is whether or not what you can say about a thing is already contained in the meaning of the thing. Since analytic judgments can be made in most cases without having to appeal to experience, the happen to be a priori judgments as well and in most cases, synthetic statements happen to be a posteriori judgments.

Therefore, every meaningful statement is known as true or false either by definition, in which case, it tells us nothing about the world, or by experience. For example, propositions such as "thre is a God" or there is a spiritual self" are not true by definition not are they based on sense experience. Therefore, they are meaningless statements.

Hume also explores the relationship of Cause and Effect. He asks what it means to say that we know that events have causes. When we try to trace such knowledge back to experience, we discover that all we mean by saying that A causes B is that A occurs before b, A seems to be near B in space and time, and in our experience events like a seem to be followed with some regularity by events like B. However Hume argues that we do not experience a "necessary" connection between A and B. We have a natural inclination to assume that A caused B and desire to assume this to be true, and there may be a high probability that A did cause B, but all we can really "know" is that A and B occurred together in close proximity of time.

In addition, Hume takes his conclusions and applies them to the issue of the continuity of self. According to Hume, we are dependent upon memories to assure us of the continuity of our "self" into the past. But we have no sense datum to provide us with the assurance of the existence of self in the past and memories not a legitimate means of knowledge. Consequently we can only know what we are presently experiencing and even that is questionable or doubtful since this might be illusion. Consequently, in the end we are compelled to doubt whether knowledge is possible at all and we are left only with skepticism.

Epistemology: Empiricism - Berkeley (1685-1753)

George Berkeley was born and educated in Ireland. In his early 20's Berkeley worked out his philosophical theories and also wrote his two most important works, A Treatise Concerning the Principles of Human Knowledge and Three Dialogues Between Hylas and Philonous.

Berkeley was not so precise as was Locke. He dismissed Locke's concept of general ideas, as well as Locke's distinction between primary and secondary qualities. For Berkeley everything boils down to "perception." Behind "ideas" there is no material substance. The entire material world is only a representation or a perception. The only thing, which exists, is the spiritual Self and Berkeley claims that we can have an intuitive certainty of this. All ideas proceed from god. It is God who puts these ideas into our spirit. With Berkeley, once again God is the foundation for all that exists.

Berkeley concluded that we know as real only what we experience and that we experience only our ideas. Therefore for something to be real means that it is the object of some experience. The being of things consists of their being perceived. Berkley's phrase was esse est percipi or to be is to be perceived. It is only in the perception of an object that the object actually exists.

Immediately this conclusion raises the question as to the non-existence of something in the event that it is not perceived by someone. Berkeley's response to this question centered on God's nature. For Berkeley, God is the divine perceiver. God perceives all. Since God perceives my house when no one else does so, therefore my house continues to exist. Again, Berkeley completely rejects the concept of material substance. According to Berkeley, when we say that a thing exists we mean nothing more than that we perceive it.

Epistemology: Empiricism - Locke (1632-1704)

John Locke was the first important proponent of Empiricism in 17th century England. Locke was a medical doctor by training and attempted to work out a theory of knowledge in terms of sensory experience. Locke demonstrated how various concepts or ideas come from different types of experiences and he was insistent that we possess no innate ideas, in contradistinction to the Rationalists.

Locke's most important work is his Essay concerning Human Understanding.

Locke used the word "idea" in a very general sense to refer to everything that the individual thinks or perceives or the entirety of consciousness. Locke described ideas as either Simple Ideas or Complex Ideas.

Simple ideas are those, which cannot be analyzed into anything simpler and he further categorizes simple ideas into two types: the objective and the subjective. Objective simple ideas include primary qualities whereas the subjective simple ideas include secondary qualities.

The primary qualities include such things as number, figure, extension, motion, and solidity. These qualities belong to the body being observed and cannot be separated from the particular body.

The secondary qualities include such things as color, odor, taste, and temperature. These are subjective sensations of the individual who perceives them, the taste of sugar, the smell of a rose.

Memory is the basis on which complex ideas are formed. Simple ideas are not instantaneous but leave an impression in the mind and consequently them can be combined or assisted with other ideas. The modes, the notions of substance and relation are complex ideas and result from the associative activity of the mind.

For Locke, all knowledge and ideas come through sensory experience. No person possesses only innate ideas. According to Locke, the indvidual is born tabula rasa or with a blank slate. At birth each individual mind is a clean white tablet upon which the experiences of life are written and consequently the individual gains knowledge. Locke proposed that there are two basic sources for Ideas: direct sensory experience and reflection upon those experiences.

Regarding the Idea of God Locke acknowledged that we do not acquire this knowledge through sensory experience. He argued that first, we now that we exist and that this cannot be doubted. Second, we know that "nothing" cannot produce "something" and since we exist, there must have been a "something" (i.e. God) who creates all that exists.

Locke is the first, or so it seems, to begin questioning the cognitive faculty, which was regarded so reverently by the rationalists. The distrust of the reason, which begins with Locke, reaches its climax in the skepticism of David Hume and also requires Kant to question the validity of rational knowledge.

Epistemology: Empiricism - Aristotle (384-322 B.C.)

"Rationalism" was a theory of knowledge based on reason. Rationalism asserted that an individual can come to know truth by reason alone and that the human mind is capable of coming to know truth. Empiricism arose out of the Renaissance and the Reformation. Essentially Rationalism was a restoration of Platonism. At the risk of oversimplification, Rationalism was a movement located on the European Continent and the notable personalities previously examined as representatives of the movement include Rene Descartes, Baruch Spinoza and Gottfried Wilhelm Leibniz.

On the other hand, "empiricism" is a theory of knowledge based on sensory perception. Empiricism asserts that individuals have no innate ideas at all other than those derived from experience, which comes to us via our senses. According to empiricism, statements can be known as true and false only by testing them in experience. Empiricism rose to prominence during the 17th and 18th centuries. Notable personalities associated with Empiricism include John Locke, George Berkeley, and David Hume. Whereas Rationalism was a Continental movement, Empiricism is generally regarded as a British movement.

Like Plato, Aristotle says that a thing or a substance is what it is and is known to be that thing in virtue of its "nature" or "essence". This is what Plato calls a "Form." But Aristotle argues that, rather than thinking that the things we ordinarily experience are imitations or copies of what is really real and which exists in the world of Forms, we should think that the things we normally experience in the world are themselves ultimately real. Out knowledge of the world is therefore ultimately based on our experience and not reason alone.

For Aristotle, the essence of a thing, such as a dog's "dogness", is what makes it to be that kind of thing. Dogness is found in all dogs, as opposed to the perspective of Plato who proposed that dogness is found in the world of Forms, and according to Aristotle this can be called a "universal." Universals do not exist apart from actual things in the world, again in contradistinction to Plato and his concept of the world of Forms. Aristotle further proposed that things could be known only by experiencing actual individual things. If all dogs were to die, the universal would no longer exist. It is in virtue of the universal that we now about dogs by knowing them in terms of their essence. But that knowledge is available only when we generalize or "abstract" the universal from our experience.

Aristotle's emphasis on using experience as the basis for knowledge is typical of an empiricist epistemology. For that reason, Aristotle may be regarded as the foundation for British Empiricism.

Epistemology: Rationalism - Leibniz (1646-1716)

While he is put into the Rationalist camp, Leibniz does not easily fit there. Leibniz published an entire work entitled New Essays on Human Understanding, addressing the empiricist conclusions of Locke, but decided not to publish the work when he learned of Locke’s death. In addition, he addressed the existence of evil and suffering and posited his concept of “the best of all possible worlds” as an explanation to the problem in his work of Theodicy.

Gottfried Wilhelm Leibniz was best known for contributions to mathematics, in particular with regard to the development of calculus. In fact he is credited with the discovery of calculus by some, while others credit Newton with the development of the mathematical calculus.

There are dimensions of Leibniz’s work that very closely resemble the conclusions of the empiricists. For example, he contended that much of our knowledge of contingent truths has its basis in sense perception (Cambridge Dictionary of Philosophy 2nd Edition, “Leibniz”, 494). His conclusions regarding necessary truths, however, reflect his belief that such truths have are a priori. (Cambridge Dictionary of Philosophy 2nd Edition, “Leibniz”, 494)

According to Leibniz, all truths are based on the Law of Non Contradiction and the Principle of Identity. The Law of Non Contradiction applies for necessary truths while the Principle of Sufficient Reason applies to contingent truths. Both of these items can be known apriori.

The Principle of Sufficient Reason in its classic form is simply that nothing is without a reason or there is no effect without a cause. As Leibniz remarks, this principle “must be considered one of the greatest and most fruitful of all human knowledge, for upon it is built a great part of metaphysics, physics, and moral science.” (G VII 301/L 227)

Leibniz also follows Aristotle in placing great emphasis on the Principle of Identity or the Principle of Non Contradiction. The principle states simply that “a proposition cannot be true and false at the same time, and that therefore A is A and cannot be not A” (G VI 355/AG 321).

Epistemology: Rationalism - Spinoza (1632-77)

Benedict de Spinoza is described as one of the "more difficult philosophers of the Rationalist school." (Philip Stokes, Philosophy: 100 Essential Thinkers, 78). Two influences dominate the thought of Spinoza: Descartes and Euclid.

Under the influence of Descartes Spinoza determined to establish a basis for knowledge in logic, while under the influence of Euclid Spinoza established a variety of ontological, metaphysical, epistemological beliefs, which are demonstrated in geometric fashion. (Philip Stokes, Philosophy: 100 Essential Thinkers, 79).

Leibniz chief work, Ethica Ordine Geometrico Demonsrata or Ethics, was published posthumously. Evidencing the influence of Euclid, the book was written in a geometrical form utilizing geometrical constructs utilizing definitions, axioms, propositions and proofs. (Colin Brown, Philosophy and the Christian Faith, 54).

Spinoza is the only Jewish thinker among the rationalists. He was excommunicated from the Jewish community of Amsterdam, possibly on account of the heretical views that he held about the nature of God, and the immortality of the soul, views later elaborated in his great systematic work cited above, Ethics.

For this writer, Spinoza's conclusions vividly demonstrate more than his peers the interrelatedness of metaphysics and epistemology. When reading Spinoza, there is a complex interweaving of metaphysical conclusions, which are based upon epistemological convictions. This interrelatedness will be evidence in the present material with regard to the discussion of Spinoza’s three levels of knowledge.

Spinoza is often described as the God intoxicated philosopher. Regarding Spinoza's understanding of the nature of "God" it appears that the best word used to describe his approach is that of Pantheism. The emphasis of Spinoza’s work lies in his focus upon God’s immanence with the created order and his understanding of God as a substance inherently present in and related to all that exists.

As such, there is a predetermined power or force (God) at work in the world of the created order, which renders freedom and free will impossible. This divine force will inevitably have its way and will progressively work out its pre-arranged purposes.

Regarding the immortality of the soul, as substance the soul is eternal and unending. For Spinoza, there is no substantive difference between the substance of body and mind or soul. Mind and body are simply terminological ways for speaking of the divinity, which permeates all of reality.

Regarding the existence of evil and suffering in the world, Spinoza concludes that the existence of evil and suffering has its roots in one's limited perspective of those categories. At this point, Spinoza’s conclusions reflect his lack of confidence in the senses. In short, Spinoza proposes that when it comes to the presence of evil and suffering, we simply do not have the entire story since sensory perception is inadequate at the least and distorting at its worst.

Interestingly, Spinoza's conclusion closely resembles much of Christian's theology regarding the presence of evil and suffering in the world which would argue that we are unable to comprehend the reason for the presence of evil in the world and that we should find comfort in the potentiality that we will “understand it all better by and by.”

Spinoza speaks of three types of knowledge: random experience or knowledge of the first king, adequate ideas or knowledge of the second kind and intuition or knowledge of the second kind.

Spinoza first speaks of the knowledge gained through sensory experience or as he labels such knowledge the knowledge of random experience. In short, "Spinoza argues that we cannot have adequate ideas of the world through sensation (Ethics II, propositions 16-31; Cambridge Dictionary of Philosophy, 2nd ed., 772). The senses provide only a "superficial" acquaintance" of self and of the external world. For Spinoza the senses are "an invariable source of falsehood and error" and are also the source of "delusion." (Stanford Encyclopedia of Philosophy Online, "Baruch Spinoza")

In his Ethics Spinoza concludes that the senses may be a more remote means to authentic or legitimate knowledge, but the senses are never reliable enough to constitute a primary means or even an adequate means for knowledge. This is true since, according to Spinoza, the sense is imperfect and is derived from vague sensory experience. For Spinoza, sensory experience only provides inadequate ideas and cannot be relied upon as a source of truth.

Second, Spinoza also speaks of "adequate ideas." According to Spinoza, this knowledge begins with simple adequate and innate ideas and proceeds to analyze causal or logical necessity between objects. This knowledge of the second kind provides us with truth in contradistinction to any knowledge gained through sensory experience. According to Spinoza this level of knowledge "involves grasping a thing's causal connections not just to other objects, but also more importantly, to the attributes of God and the infinite modes that follow immediately from them" (SEP, Baruch Spinoza)

Spinoza's conclusions regarding this second level of knowledge optimistically supercedes the conclusions of Spinoza's predecessor Descartes and his optimism regarding the potential of Reason to enable us to grasp all of Nature or "God". In short, Spinoza seemed convinced that through the use of Reason we can know all there is to know of God, God's attributes, and all things related to God. (SEP, Baruch Spinoza)

In addition, Spinoza speaks of a third level of knowledge, the knowledge of intuition. Spinoza takes his theory of knowledge one step further with this level of knowledge and optimistically claims that the mind can genuinely and ultimately deduce and can intuitively come to the recognition that all Reality is the essence of God himself. "This third kind of knowledge, intuition, takes what is known by Reason and grasps it in a single act of the mind." (SEP, Baruch Spinoza)

Epistemology: The Rationalists - Descartes (1596-1650)

Knowledge for the rationalist is what can be deduced from principles that cannot be otherwise. These facts are considered to be undoubtable or indubitable. Examples of these kinds of principles include statements such as: Bachelors are unmarried males. A thing cannot be and not be at the same time in the same way. Triangles have three sides. A whole is always greater than any one of its parts.

These kinds of statements are known with certainty to be true because the very meaning of the terms involved, terms such as bachelors, triangles, things, wholes, requires that because we think of them in certain ways. In other words, we do not need to rely on sensory experience in order to "know" these things to be true. Consequently, we know about some things prior to sensory experience or a priori. Knowledge that comes after sensory experience is a posteriori.

Rene Descartes is another example of a rationalist. Instead of beginning philosophical inquiry with the study of the nature of reality, he suggests that we ask what it would mean to know about reality. To believe that reality is fundamentally water or some other "thing" is beside the point for Descartes unless we know first whether our belief itself is justified. To determine whether our beliefs are justified, we have to be able to trace them back to a statement, belief, or proposition that cannot be doubted. Descartes is searching for the one proposition upon which all other statements regarding truth can be founded.

Descartes arrives at this one basic proposition through a "suspension of belief" which has come to be known as "Cartesian Doubt." Certain individuals regard Descartes conclusions as bordering on the absurd, but the individual should understand that Descartes is only hypothetically or in a matter of speaking suspending all other beliefs in order to arrive at the one belief which he can "know" or attach himself to in order to reconstruct all other truth. In essence, through the use of Cartesian Doubt, Descartes is calling upon us to "pretend" that all is false with the exception of what has been called "The Cogito."

Descartes rejects knowledge based upon the senses or, as it has been called, a posteriori belief. For Descartes sensory experience cannot be regarded as true. One of the reasons for this conclusion on Descartes part is his speculation that we might be dreaming. In light of this possibility, we cannot be sure of the past, we cannot be sure of the external world, and we cannot be sure that other people have minds. In addition, Descartes also rejects mathematical truth, such as the proposition that 6 + 3 = 9. Neither can we trust the concept that all triangles have three sides since, in Descartes opinion, a demon may be deceiving us.


However, Descartes concludes that there is one truth of which we can be sure. We cannot be mistaken that we are thinking according to Descartes. From this idea emerged Descartes proposition, "Cogito ergo sum" or "I think therefore I am." "Thinking" proves that we exist. From this starting point, Descartes determines that he can begin constructing other truths; such as the truths of Identity and that things are composed of substances. For Descartes these qualities so to speak are innate since they are not determined by empirical experience.

However, Descartes was confronted with the possibility previously posed. What if he were being deceived by the so-called "evil genie"? Descartes does away with this possibility by positing the idea that an all-powerful, all good God would not permit this happening. Descartes attempts to prove the existence of God based upon the one thing that he can know for sure, the Cogito. Simply put, Descartes posits that he can posit the concept of imperfection and that the justification for this conclusion is based upon the existence of his doubts. Consequently, he must have some concept of "perfection" or else he would not know what "imperfection" is. He then concludes that he does not know what "perfection" is in and of himself. Rather he knows of "imperfection" because there must be a "God" who is perfect and thereby defines by his very being "perfection." Since God is perfect, he must also be all good and all knowing. As such he would never tolerate the existence of an evil genie, which would deceive. Therefore, God's existence, which has been proven for Descartes, disallows the possibility of the existence of an evil genie.

In short, for Descartes, certainty regarding other matters such as the existence of the external world is based upon knowledge of self.

Epistemology: The Rationalists - Plato (427-347 B.C.)

Plato is an example of a rationalist. Plato argued that sense experience fails to provide us with any guarantee that what we experience is, in fact, true. The information we get by relying on sense experience is constantly changing and is therefore unreliable. Such knowledge can be corrected and evaluated for dependability only by appealing to principles that do not change. These unchanging principles or "Forms" are the bases of what it means to think or reason in the first place. If we can show that an opinion or belief we have is based on these undoubtable principles of thought, we have a firm foundation for the opinion. That foundation is what allows us to think of a belief as more than simply opinion; it is what allows us to identify the belief as justified and true, and that is what is meant by knowledge

In short, in order to have knowledge or justified true belief, we have to transcend the ever changing flux of the physical world and grasp a permanent rational order behind the flux, an order that will demonstrate the universal in the particular. This "grasping" is an intellectual act of the mind, which, in its purest manifestation, is exclusively formal or mathematical. Such an intellectual act can take place only if there are certain innate ideas upon which it can be based. "Knowing", then, is an act of making the observable world intelligible by showing how it is related to an eternal order of intelligible truths.

In other words, the world of changing, material objects or the visible world is merely a fleeting image of the intelligible world. This is what Plato called the realm of the Forms. Physical objects are real only insofar as they are intelligible only in terms of that which does not change. So a thing is what it is in virtue of something that is not changing. But since the visible world is constantly changing, it cannot be used as the basis for identifying what things are. There must be an intelligible or non-sensual realm in terms of which physical things are said to exist intelligibly. That, according to Plato, is the realm of Forms.

Plato's simile of the sun, image of the divided line and allegory of the care are intended to clarify exactly how the things we experience in the sensible, ordinary world, things such as chairs, drawn triangles, are less real than the ideal models or Forms on which they rely for their existence and in terms of which they are intelligible. Just as drawings, reflections, or copies of sensible objects are not as real as the sensible thing on which they depend, so sensible things are not as real as the concepts in terms of which they are identifiable.

Concepts that rely on sensual imagination for their intelligibility, for example things such as mathematical concepts such as triangularity, are more real than, say triangular blocks or wood or drawings of triangles. But even though concepts that are based on sense experience are not limited to any particular expression and are unchanging, they are not as real as the Forms, which do not rely for their existence or intelligibility on anything sensual and unchanging.

Some Forms, such as chairness, are the ideal models in terms of which physical objects, such as chairs, exist and are intelligible. Other even higher Forms such as equality or justice provide the means by which not only physical objects, but also activities, relations, and even lower Forms themselves are identifiable. The Forms are not abstractions or generalizations based on our sensual experience of physical objects; rather, we know physical objects as what they are by knowing them in terms of their Forms.

As such, in order to know that a chair is a chair, we have to know what chairness is first, and that means that we cannot begin with sensible experience. Likewise, in order to know that two numbers are equal, or that an action is a just action, we have to know first what equality or justice is. But that already assumes we know what what an action is; and that can only be known by appealing to lower Forms that rely for their intelligibility and existence on higher Forms. The highest Forms are themselves intelligible and exist ultimately in terms of the "super" Form, the Good.

Thus, with Plato we have a much more full blown beginning to Rationalistic Epistemology.

What is "Epistemology"?

The word "epistemology" derives from the Greek word episteme meaning "knowledge" and logos, meaning "explanation". Literally the term means "the explanation of knowledge". Essentially the word means "the stud of the nature of knowledge". (The Cambridge Dictionary of Philosophy, 2nd Ed, 273). At the risk of oversimplification two categories of knowledge have been assessed in the history of Philosophy since the 17th and 18th centuries. During these periods the European Rationalists argued that knowledge is apriori, or before experience. After that period of time, the British Empiricists argued that knowledge is aposteriori, or after experience. The European Rationalists included Descartes, Spinoza and Leibniz while the British Empiricists included Locke, Berkeley and Hume. Immanuel Kant reconciled the two schools with his version of German Idealism.

Aposteriori knowledge is that knowledge which depends upon sensory experience while apriori knowledge is that knowledge which is innate, or prior to experience. Apriori knowledge is that knowledge, which the individual innately possesses, such as mathematical knowledge, or knowledge of logic, while aposteriori is knowledge of extant physical, observable objects. The Rationalists are generally characterized by a belief in the rationality of the universe and in the ability of human reason to grasp the universe. Behind the complex machinery of nature is a rational mind and through the right use of reason this rational mind can be known. While the rationalists attempted to develop a philosophical system according to the so-called self evident truths of the human mind, the empiricists stressed the part played by experience in obtaining knowledge. The empiricists argued that we have no ideas at all other than those derived from experiences that come to us by our senses.

In brief and at the risk of oversimplification, the rationalists had their beginnings in the philosophy of the ancient Greek philosopher Plato, while the empiricists had their beginnings in the ancient Greek philosopher Aristotle. In subsequent material we will examine more closely the works of these individuals.

What Difference Does Metaphysics Make?

The term "metaphysics" emphasizes the transcendent. How have individuals understood the transcendent? This seems to be the key question in the metaphysical quest. As will be seen, especially with regard to the Logical Positivists and those associated with the philosophic school of linguistic analysis, the interest in the transcendent has generally faded and is consequently regarded as beside the point or setting up an impossible quest, or as a contemporary reinterpretation of the transcendent.

But eventually one has to ask what difference one's metaphysical perspective makes? Ayn Rand proposes an interesting imaginatory situation in which one lands on an unknown planet. In a much more eloquent fashion than this writer is capable of presenting, Rand says that in such an alien, strange, and unfamiliar environment, an individual would be concerned with three primary questions: Where am I? How do I know where I am? And how should I live in this newfound context? She points out that these three questions correspond to the central questions of Philosophy, each of which is related to the other:

• The Question of Metaphysics: Where am I?
• The Question of Epistemology: How do I know where I am?
• The Question of Ethics: How should I live or survive in this new context?

According to Rand, and I think she is right at this point, the central questions of human existence begin with the metaphysical quest.

Regarding the significance of Metaphysics, it is important in four ways:

1. The Personal Dimension: Metaphysical contemplation assists us in our search for our own meaning. It seems that in each human being regardless of life status there is an incessant desire for answers to questions regarding our place in the universe. Metaphysical speculation moves us not only toward attempting to determine the nature of the cosmos in which we live, but also to a quest to find our own place in that cosmos. Can I find meaning in this life? What is the summum bonum of life? Is possible that I can genuinely find purpose in life in my present existence, or must I wait upon the next life, if such a life is believed to be possible, for personal fulfillment? While each individual can become overly obsessed with himself or herself and the quest for purpose in life can potentially be reduced to a narcissistic journey, the fact none the less remains that there is something in the individual which compels us to this personal quest for purpose. In addition, the fact that humans have searched for purpose in life by going down such false avenues as substance abuse, sexual exploitation, and the idolatry of career or education evidences the need for metaphysical speculation and reflection.

2. The Spiritual Dimension: Metaphysical contemplation assists us in answering life's deep and profound questions. As philosophers have indicated through the ages, humanity is consistently concerned with the profound questions of life. This is true in that, even though the answers proposed to those questions vary, there is nonetheless still a metaphysical longing for answers to profound and complicated questions such as does history have a purpose? Is history headed anywhere? How does one come to "know" anything? How can we "know that we know" the answer to life's profound questions? Is there any such thing as Truth? What is the role of science in the quest for knowledge? Each of these questions and the many others associated with the spiritual nature of human existence begs for the assistance given by metaphysical reflection.

3. The Relational Dimension: Metaphysical contemplation assists us in our view of human personhood. There is something about metaphysical pondering which shapes our view of what it means to be "human." Is the human animal to be understood as a body and spirit or soul? Is the human animal to be understood as nothing more than a physical entity? What are the consequences of viewing others through the lenses of either of these approaches? Do the implications of metaphysical speculation for the nature of human personhood also have implications for how I regard not just myself but also others? If so, what are those implications? In addition, what about the non-human animal? Not only do I co exist or co-reside with fellow humans, but also non-humans. How am I to regard these creatures in light of Metaphysical conclusion? The Relational Dimension of individual existence is inherent within one's Metaphysical speculation and conclusions.

4. The Social Dimension: Metaphysical contemplation assists us in our humanitarian concerns. Closely related to the above concerns is also concern with the ultimate direction and outcome of this life. Do my Metaphysical conclusions, or lack of conclusions, shape the extent of my optimism about the outcome of this Reality, as I understand it? Do my Metaphysical speculations lead to an optimism or pessimism regarding the future? Do my Metaphysical convictions lead me to a pessimism that forces me to an 'anti life" perspective to use Nietzsche's term and consequently make me of such a heavenly mind that I am of no earthly use? What are the implications of my Metaphysical conclusions for how I view the environment, hope for human progress, or the political order under which I live?

In short, once properly understood, Metaphysical conclusions lie behind each of the more highly specialized concerns which one addresses in philosophy. Consequently, Metaphysical ponderings are a necessary prerequisite to serious philosophical speculation on areas such as epistemology, philosophy of religion, ethics, political speculation, aesthetics, as well as any other topic of concern under the heading of philosophy. Metaphysics truly does make a difference.

What is "Metaphysics?"

Andronicus of Rhodes, the editor of Aristotle's library, coined the term "Metaphysics" while arranging Aristotle's library. According to the story, while arranging Aristotle's library, Andronicus came across a group of works from Aristotle, which transcended the topic of Physics. Since the content of these works addressed issues beyond physics, the works were entitled After Physics or Metaphysics.

According to some, however, the term is a compound of two Greek terms. "Meta" is a Greek preposition and means "after" or "beyond" while "phusis" signifies "nature", and though this meaning of the term is not common, it was allegedly used by the Greeks to denote that "the universe."

The term "Metaphysics" is, as is obvious, closely related to the term "physics" which speaks of the scientist who is concerned with the basic laws of nature. The term "Metaphysics" goes beyond the study of nature and "investigates matters somehow transcending those investigated by physics." (Peter van Inwagen, Metaphysics, 3rd Edition, Boulder: Westview Press, 2009, 19-20)

It appears however that the better understanding of the origin of the term is that associated with Andronicus of Rhodes.

The term "Metaphysics" refers to "the totality of things for what they are." (Marias, History of Philosophy, 64) Other disciplines study portions or slices so to speak of reality. For example, Botany is the study of vegetation while Mathematics is the study of figures, numbers, and measurement. Aristotle goes to great lengths to emphasize the oneness of the study of metaphysics. A number of emphases characterize Aristotle's proposal regarding the single or unitary nature of Metaphysics.

Aristotle concludes that while Metaphysics is to be understood as a single science, it is also to be regarded as the science of Being, the science of God and also the science of Substance.

A variety of questions exist under the heading of Metaphysics. While these questions are usually considered in addition to the subject matter of Metaphysics, each of these concerns has metaphysical roots, metaphysical implications or include metaphysical assumptions. Some of these questions are:

• What is Metaphysics? This metaphysical question addresses issues such as the nature of appearance and reality. In addition, the question contains the discussion of metaphysical methodology. For example, how does the scientist approach the issue of Metaphysics as opposed to the theologian? How are these two disciplines different in their methods of pursuing an answer to the questions of Metaphysics? What are the implications of these two divergent approaches to the metaphysical task?

• Is there a plurality of things, or is there only one thing? That approach which advocates that reality is composed of one thing so to speak is designated as “monism.” That view of reality which argues that all reality is made up of a duality or things is labeled as “dualism.” That view of reality which contends that reality is made up of innumerable qualities, in fact too numerous even to grasp in some instances, is appropriately called “pluralism.”

• Is there an external world, a world of things that exist independently of human thought and sensation? This question has its primary basis in the philosophical skepticism of Rene Descartes. Descartes made his way into the “stove room” by his own account, which likely has reference to the heated room in his home, and from that experience of isolated pondering Descartes, according to his own testimony, emerged with his entire philosophical methodology in tact. Thus was born “Cartesian Doubt”, the employment of which leads inevitably to a great variety of problems not the least of which is the “problem of the external world.”

• Is time real? Is there a variation in individuals’ experience of time and if so how do we explain this variation? As time bound creatures can we even begin to ponder the possibility of timeless existence?

• Is there such a thing as objective truth? How do we determine that which should be regarded as Truth? Is there an objective criterion for determining truth or is the determination of Truth essentially the subjective determination of a variety of "truths"?

• Why is there something rather than nothing? Under this heading lies the examination of the questions which are central to the Philosophy of Religion regarding the Cosmological and Ontological Arguments for God’s existence, the existence of evil and suffering, the attempts at the rational explanation of why some individuals choose incorrectly to believe in the existence of God, the Principle of Sufficient Reason and questions concerning the contribution of science to the question.

• Why are there rational beings? Once again, this question causes us to ponder the issues of order, structure and design in the universe which issues are central to the Philosophy of Religion’s discussion of the Teleological Argument for God’s existence.

• Are we physical or non physical beings? From this question emerges other questions such as what is the nature of man? Is humanity to be understood as a dualistic entity consisting of body and soul? Is humanity to be understood in a naturalistic materialistic fashion, simply one more physical creature among many and essentially being no more and no less than a physical entity? How does this question evoke further contemplation of personal identity or questions concerning the nature of the human mind? What is the human mind? Does the human mind actually exist? Is the human mind simply to be understood in terms of physicalism or a series of electrical impulses firing across the synapses of the brain? Is the human mind to be understood as nothing more than a biochemical occurrence? What is the relationship of the human mind to the human body?

• Do we have free will? Is freedom possible? Can we know if we are free? Are there degrees of freedom and ways of increasing or threatening free will? Does it matter whether or not we are free?

So it is apparent that metaphysics is a complicated concern of the Philosopher not only by virtue of the difficulty of determining its nature, but also by its broad diversity. Ultimately, in this pragmatic age in which we live, one is forced to ask and answer the question, "What difference does it make?" (See Peter Van Inwagen, Metaphysics, 3rd Edition)

Metaphysics: Parfit (b. 1942)

Much ontology and metaphysics as practiced by modern professional philosophers is often concerned with the dry conceptual and logical matters. But there still remains an interest in what is perhaps the oldest ad most mysterious metaphysical question: Why is there anything at all?

The Oxford philosopher Derek Partfit tackles this question. Parfit raises the much-debated question of why the initial conditions of our universe were "fine-tuned" in such a way as to allow stars, planets and life to exist. Some say this was just a coincidence; some that God designed it so; some that ours is merely one of countless universes only a few of which are fine-tuned.

But this does not touch the "Why anything?" question.

Antecedently, there seems to be a number of "global possibilities", for instance that every conceivable world exists, that only some possible worlds exist and that nothing exists. Perhaps the last, which is called the Null Hypothesis, would leave nothing to be explained.

Parfit maintains that even such an empty scenario or a non-scenario would still require explanation though he does suggest that it might be the easiest possibility to explain because it is the simplest. But whether simple or not it does not get us much further forward, since it is not the possibility that actually obtains: here we all are, so there is, in fact, a universe.

Interestingly Parfit asks whether there could be a theory about the existence of the universe that leaves nothing to be explained. The belief in God is often supposed to provide such a complete explanation but Parfit considers instead a slightly different position, which he calls the "Axiarchic View" which is that the universe exists because its existence is good. This view he rejects however (just as, implicitly, he rejects the theistic view) on account of the notorious problem of evil.

The interesting answer Parfit eventually leaves us with is that it may be just a "brute fact" that the universe exists. On this view, not only would the universe have no cause, it would have no explanation of any kind. So we should not look for any selector, any feature like being best or most simple, or including God, which accounts for why there is a universe or many universes or no universes. The universe just “is”.

The mind may revolt at such apparent arbitrariness or randomness but Parfit argues that there is no need for hidden machinery behind the existence of the universe. It is clear that in such cosmological speculations the human mind is working at the very limits of its capacity (interesting). Critics of Parfit's argument may wonder whether the timeless overarching framework of logic, which he takes to support the plausibility of the Brute Fact View, does not itself presuppose that reality is not in the end random and arbitrary. However that may be, such "ultimate" metaphysical inquiries about the universe and its origins seem sure to remain a part of philosophical inquiry as long as human beings confront the mystery of existence.

Metaphysics: Quine (1908-2000)

Willard Van Orman Quine was one of the most distinguished analytic philosophers of the twentieth century He takes a down to earth approach to philosophical questions regarding ontology or being. Quine is part of that movement previously referred to as Logical Positivism though he is not uncritical of the movement. Quine and those of his metaphysical persuasion have been variously called empiricists, logical positivists, neopositivists, who advance their own conclusion regarding what can be deemed as “real" or "truth" under the various titled methodologies of "scientificalism" or "physicalism".

In some sense Quine and his peers are "anti metaphysicalists" in that some propose that metaphysics is impossible or meaningless and that metaphysical statements are simply statements of emotion due to their lack of verifiability. Quine, as with Carnap, understands philosophical problems in general and the problem of metaphysics in particular, as nothing more than a problem of the imperfection of language. Consequently, the philosophical/metaphysical task is reducible to nothing more than linguistic analysis.

Central to Quine's metaphysics is his conclusion regarding the ultimacy of scientific statements. According to Quine, science is the ultimate basis for truth. This conclusion on Quine's part evidences that he is a radical empiricist. He completely rejects the synthesis of both rationality and empiricism presented by Kant.

However, Quine also advances criticisms of Logical Positivism. For Quine, Logical Positivism possesses two weaknesses. First, Quine challenges Kant's proposal that regarding the exclusiveness of analytic (all bachelors are unmarried males) and synthetic statements (It is raining outside). Second, Quine challenges the positivist conclusion that the meaning of a statement can be reduced to sensory stimulation and yet it seems that that is exactly what Quine is proposing to a great extent.

For Quine, no proposition can be true independent of sensory experience and every proposition's meaning must be determined in light of the individual's "web of beliefs" of which the proposition is a part. For Quine, theory and experience are inseparably and inevitably linked.

In summarizing Quine's metaphysical conclusions, it seems that Quine goes so far as to propose that the scientific model constitutes a more than adequate model for the discipline of philosophy and this conclusion renders useless most of the metaphysical speculation of some of the great philosophers of the past.

Metaphysics: Carnap (1891-1970)

The whole enterprise of metaphysics came under heavy attack in the 1920's and 30's from a group of philosophers originally based in Vienna who came to be known as Logical Positivists. Logical Positivism had its roots in the skepticism of David Hume. Hume rejected the claims to metaphysical knowledge. For example, Hume rejected belief in the existence of God or the immortality of the soul since according to Hume the ideas on which such claims regarding these subjects are based cannot be traced back to the simple sense impressions.

The Vienna Circle, including individuals such as Morris Schlick, A. J. Ayer, and Ludwig Wittgenstein, determined that all religious and ethical statements are nonsensical since such statements cannot be empirically verified. This criterion was given the designation The Principle of Verification. Prominent among the Logical Positivists was Rudolph Carnap. Carnap's position is that the traditional claims of the metaphysicians are, in the strict sense, meaningless and that they are "pseudo-statements" in that fail to assert anything at all since these statements cannot be verified.

The Logical Positivists in general and Carnap in particular essentially attempted to create a way for metaphysical speculation to die. However, such was not to be the case. It appears that Carnap recognized that absolute verification was impossible and that a mediating position must be developed regarding truth. Carnap determined it important that in absence of the possibility of absolute certainty regarding a proposition or statement, one is forced to explore the realm of possibility. Thus was born Carnap's continual search for a theory of and a method for the calculation of probability.

As a result Carnap determined that one must distinguish between two senses of probability. On the one hand there was" probability (1) which corresponds to credibility, and probability (2) which corresponds to the frequency or empirical conception of probability." (Cambridge Dictionary of Philosophy, "Carnap", 118)

Carnap, like his predecessors in the Vienna Circle, contended that many of the individual words used by metaphysicians are nonsensical. This is true since such words fail to meet the criterion of verification. For Carnap the only meaningful statements are either those which are true by virtue of their form, or those which are empirically or scientifically verifiable. Statements, which fail to meet these two criteria, are nonsensical or meaningless.

Carnap, however, preferred the term "problem of confirmation" rather than "problem of verification", arguing that a sentence may not be testable but may be confirmable. According to Carnap, a sentence is confirmable when we may know the method for confirmation but are unable to utilize the method for actual testing. (50 Major Philosophers, 156) For Carnap the only meaningful statements are those, which meet the following criteria:

1. There are statements, which are true solely by virtue of their form or are tautologically true. These statements correspond to Kant's analytic statements and these statements say nothing about reality.

2. There are the negations of such statements or contradictions. These types of statements are contradictory and are false by virtue of their very form or structure.

3. The truth or falsity of all other statements lie in the "protocol sentences" and these are true or false empirical statements and they belong to the domain of empirical science.

Carnap concludes, "Any statement which does not fall within these categories becomes automatically meaningless." (Carnap, "The Elimination of Metaphysics" in Western Philosophy: An Anthology, ed. Jon Cottingham, 125).

Carnap concluded that traditional metaphysical statements are worse than fairy tales in that at least fairy tales are at least capable of verification or falsifiability. According to Carnap metaphysical assertions fail to make any intelligible statements whatsoever. Metaphysics rejects analytic statements and does not utilize empirical methodology. Therefore metaphysics is forced to employ pseudo language. (Carnap, "The Elimination of Metaphysics" in Western Philosophy: An Anthology, ed. John Cottingham, 125) Carnap essentially reduced the complete task of Philosophy to nothing more than "the business of linguistic analysis." (Philosophy: 100 Essential Thinkers, 173)

Despite the vigorous and in some ways salutary challenge it offered, the program of the positivists for the elimination of metaphysics had ground to a halt by the 1960's. There turned out to be serious problems in formulating the verification principle in a way, which was stringent enough to exclude traditional metaphysics yet liberal enough to accommodate the complex theoretical statements of natural science.

However it should be pointed out that Logical Positivism seems to have died at the hands of its own criteria. In short, how does one verify the verification principle? In addition, the theoretical dimensions of the scientific endeavor also failed to pass the call of Logical Positivism for determining truth only through that which is empirically verifiable.

Metaphysics: Heidegger (1889 - 1976)

Kant's critique of traditional metaphysics aimed finally to lay to rest the claims of philosophers to describe the ultimate nature of reality as it is in itself. Many of those who followed him continued to practice metaphysics, and still sought to provide a general philosophical view of the world and our place in it, but the characteristic orientation of these inquiries now tend to allow a central role to human consciousness.

In the early twentieth century the German philosopher Martin Heidegger reintroduced the fundamental question of "Being' as the chief topic of philosophy. Heidegger was convinced that Philosophy had been asking the wrong questions since the period of the ancient Greeks, specifically since Plato. The error of philosophy lay in the emphasis, which had been placed upon "dualisms" such as the subject object dichotomy.

In his monumental work "Being and Time" Heidegger insisted that the question of being must be prior to all other philosophical inquiries. In this he was partly harking back to Aristotle's notion of a general metaphysics of being qua being, a general "ontology" mapping out the fundamental categories of being, over and above the detailed descriptions of the particular sciences. Heidegger's life long project centered upon answer the question of being. Heidegger rejects the traditional approach to metaphysics, which attempted to discover the "properties" of being. Rather, Heidegger searched for "the background conditions that enable entities to show up as counting or mattering in some specific way in the first place" which he equates with "authentic existence." (Cambridge Dictionary of Philosophy, 2 Ed, 370))

Heidegger's early work focused upon the significance of "Dasein" or human existence. The term translates as "being-there" and should understood as "a perspective from which action originates." (Philosophy: 100 Essential Thinkers, "Martin Heidegger, p. 151) Heidegger emphasized the categories of "authenticity" versus "inauthenticity" as related to human existence. According to Heidegger we are authentically human to the extent that we are fulfilling our true purpose in relation to the world around us. In this context, Dasein becomes a unitary function of the individual in relation to the surrounding world.

The analogy of the hammer is helpful for understanding Heidegger's emphasis at this point. In Heidegger's understanding a hammer has authenticity through its practicality in that in the workshop in which the hammer is it does not stand-alone. Rather, the hammer exists in the context of relationships and is used for the purpose of uniting boards in order to construct bookshelves for the purpose of containing books so that the individual may study and be an organized and neat context for study. In this sense, Heidegger reminds us that an entity does not exist in isolation from others, but only in the context of a complexity of relationships.

However, Heidegger reminds that there is also the risk of "inauthenticity". For Heidegger, inauthenticity consists of the individual's potential drift of focus upon his purpose in life. There is the inclination in every human to experience a sort of existence drift in which the individual becomes swept up by the crowd, goes along with the crowd, thereby losing a sense of personal significance.

This failure of focus requires that we face up to the reality of our mortality, which in turn will bring us back to a striving for authentic existence. In short, no one ever lives authentically until they have addressed their own morality. "It is precisely death that allows human life to have meaning" and we are "to live in the realistic anticipation of death." (Newport, Ultimate Questions, 292) In this sense, Heidegger is very concerned with the acknowledgement of death. "To be authentic is to clear sightedly face up to one's responsibility for what one's life is adding up to as a whole." (Cambridge Dictionary of Philosophy, ed. Robert Audi, 372, "Heidegger", 372)

Heidegger's philosophy constitutes not only a decisive, but also a unique and highly significant turn in metaphysic speculation. His approach to philosophy forms part of what has come to be known as existentialism, an approach that starts not from the objective definitions or essences of things, but from the immediate predicament of the existing human being as he or she confronts the world.

The Heideggerian metaphysic thus turns out in the end to be not an abstract study of being, but rather an enterprise where understanding and valuing are inextricably intertwined. In coming to terms with the world we are drawn into a practical community of other involved agents, and thus into "solicitous concern for others" or what Heidegger calls Sorge, or Caring. Despite its complexity, Heidegger's insights and proposals merit not only in depth analysis, but also personal contemplation of light of one's own existence.

Metaphysics: Kant (1724-1804)

Immanuel Kant’s epistemologic perspective is a blend of both rationalism and empiricism and has implications for his theory of metaphysic of transcendental idealism. Kant was educated in the rationalistic tradition, but under the influence of David Hume Kant became more sensitive to the Empiricistic perspective. In short, Kant's approach was a synthesis of the rationalistic and empiricistic perspectives. According to Kant, reason provides the structure of what we know while experience provides the content of what we know.

As a rationalist, Kant concluded that there are built in or categories of the mind. In other words, while the mind is a blank slate, it also contains innate categories such as space, time, quantity, qualities, relationships, and modality. According to Kant, the individual mind takes ideas and interprets them in light of these categories. Regarding those categories, Kant specified,

1. Space: We do not perceive space since space is not actually an object but is "nothingness"; however, we do perceive objects in space. Space is actually the nothing between the objects.

2. Time: Time as the individual experiences it does not move at the same rate with all individuals. There is a variation of time from individual to individual.

3. Quantity: The individual's mind is innately capable of interpretation of such things as plurality, totality, and unity. The ability to do so is "hardwired" into the human mind.

4. Qualities: The individuals' mind is capable of interpretation of sensory data through categories such as the real and the not real.

5. Relationship: The individual mind comprehends things in relationship to one another through such categories as cause and effect and reciprocity.

6. Modality: The mind is capable of interpretation and categorization through an innate awareness of things such as possibility and impossibility and necessary and unnecessary.

All of these categories, according to Kant, are subjective. They are built into the mind, so to speak, with the result that we cannot know for certain the extent to which they are part of the real world. The mind literally transforms our sensations from the external world (sensory perceptions) into ideas. Therefore, sensory data is turned into an idea and is stored for future reference. Again, regarding the external world, Kant concluded that one does not actually perceive the object itself. Rather, the individual only perceives what the object appears to be. For Kant, there were two categories for reality.

Kant's understood reality as consisting of three worlds. The first world or level of reality proposed by Kant was that of the Human Mind. For Kant, the world of the human mind lies within the person and consists of knowledge derived from the second world or Phenomenal World. The Phenomenal World is that which can only be sensed or the world of empirical observation. However Kant was not content to conclude with these two dimensions of reality. For Kant there was a level of knowledge and a level of reality, which was not apriori or aposteriori, not comprehended by human reason or by the individual senses. This is the world of "God" and the "soul." Kant labeled this third level of reality as the Transcendental World.

Metaphysics: Hume (1711-1776)

By the time of the mid-eighteenth century a diversity of metaphysical theories had been proposed. In summary, Locke emphasized the role of the external object, attributing to the actual extant object both primary qualities, those qualities that are actually part of the existing object, and secondary qualities, those qualities that exist in the perception of the observer. Leibniz proposed the theory of "individual substances", designating them as "monads" and describing them as "active centers of energy." With Berkeley's proposal emerged the "total denial of material substance" while placing an emphasis upon the role of the perceiver and, in so doing, invariably linking the existence of an object with the perception of that object. (John Cottingham, Western Philosophy: An Anthology, p. 102)

David Hume introduced a new level of ontological and epistemological skepticism. Hume asserted that the notion which Locke had referred to, of an unknown "something" supposed to "support qualities” was an "unintelligible chimera". Hume proposed that our knowledge of an object cannot go beyond our experience and further that experience is no guarantee of what may be known or how we may know reality. He argued that our ideas of bodies are nothing but collections of ideas formed by the mind.

Hume divides all the objects of legitimate human inquiry into two classes which he called 'Relations of Ideas" and "Matters of Fact". Relations of Ideas, typified by the truths of mathematics, are established a priori or independently of experience and they form a closed system, arising merely from how our ideas or concepts are defined. Relations of Ideas do not provide us with any information about what really exists in the world.

Matters of Fact, by contrast, are established a posteriori and are concerned with what really exists. However, neither propositions of this kind can be conclusively demonstrated and to posit the falsity of such propositions is not contradictory. For example, that the sun will not rise tomorrow is no less intelligible and implies no more contradiction than that it will rise tomorrow according to Hume. Instead such truths are based entirely on experience and all that experience reveals is what has actually been observed to happen up until now. While an event may have transpired in the past there is no guarantee the event will necessarily occur again in the future.

Hume therefore emphasizes our inability to predict, in advance of experience, how even the most familiar objects will behave. For Hume, we can never predict that "A" will cause "B". We can never say that "A" produced "B". We can never establish the relationship of cause and effect. The most we can say is that two events, which are perceived as "cause and effect" occurred in close proximity of time.

Consequently, we can never predict what will occur in the future.

For example, Hume proposed that, for all we know, when one billiard ball hits another, both balls might remain absolutely at rest. This has implications for science and the scientific method. Hume argued that while the scientist may endeavor to reduce all events to a set of laws which will establish what will occur in the future when steps A and B are taken, this is in actuality a futile endeavor since we can never know that such what will be repeated in the future even if past experience, or the scientific method, has repeatedly demonstrated the legitimacy of our conclusions regarding what may occur in the future.

The closed a priori reasoning of mathematics, on the one hand, and the limited results of actual observation on the other, exhausts the proper sphere of human inquiry. Any metaphysical speculation which tries to go beyond these boundaries should be committed "to the flames" according to Hume, because it can contain nothing but sophistry or illusion.