This lecture will attempt to engage the topic of agnosticism, its definition, its history, its relation to atheism, the various stances embraced by agnostics, and end with an extended quote by one of its most famous proponents, Robert Ingersoll, called the “Great Agnostic.”

I am most indebted to Robin Le Poidevin’s Agnosticism, and Bernard Lightman’s The Origins of Agnosticism. Le Poidevin’s volume was indispensible, not only for its facts, but for the keen insights which helped create this lecture. My talk owes a great deal to the Van A. Harvey’s and Aaron Holland’s essays on Agnosticism, as well.

Before I discuss the history of agnosticism, I am going to open with a broad definition of the term, as well as with the general meanings of atheism, deism, skepticism and theism.

There are many definitions of each term and but I am setting very wide perimeters in order to keep the various categories clear, rather than engaging in a more lengthy, precise description of each one, which is beyond the scope of this lecture.  Please keep in mind that the following definitions are arbitrary rather than nuanced. Theism is a firm belief in a god or gods.

Deism is a belief there is a creator. Many deists believe the creator designed and set the world in motion and no longer directs or intervenes in the world.  Other deists believe that god still takes an interest in matters of this world.  Atheists do not believe in the existence of any god or gods and live their lives accordingly.  Skeptics want material proof of god’s existence and are usually inclined to disbelieve in a god or gods, as they do not think there is sufficient evidence for a supreme being.  An agnostic either states that he/she does not know if god exists because of insufficient evidence, evidence that is equal on both sides of the question, or that the truth of god’s existence and/or nature cannot be known.  The stance of an unknowable god permits those agnostics who adopt it to incline to a belief in god.  Such a position will be critiqued in this talk and will be found wanting.  Many agnostics simply suspend belief in god.

Before the lecture moves into a more detailed and sophisticated discussion of agnostic philosophic positions, let us glance at a brief history of its origins.  Agnosticism’s roots lay in the classical past of ancient Greece, and the beginning of skepticism.  Pyrrho was a philosopher who lived in Greece about 365 to 270 BCE.  He was said to have traveled to India and learned about contemplative tranquility from its practitioners in that land.  He left no writings, but fortunately we have descriptions of his beliefs and teaching from his students, such as Timon.  

Pyrrho stated that certain knowledge of things is impossible, and once people realized this fact, the consequence would be a suspension of belief.  Such a suspension, he maintained, would lead people to calmness and peace, called ataraxia. Several heads of the Platonic school, the Academy, such as Carneades and Arcesilaus, were well known skeptics.

The skeptical period of the Academy was from about 266 BCE to 90 BCE.  Pyrrhonism as a school of thought was founded about the 1st Century BCE. Pyrrhonist skepticism was global, meaning it was not limited to a particular subject matter, in other words, agnosticism about everything.  In this lecture, we shall be more engaged with local agnosticism, which is confined to a particular subject matter. In this case, the subject will be the existence or non existence of god.

The thinker who preserved Pyrrhonism was Sextus Empiricus, a Roman physician and philosopher around 200 ACE. Sextus’ works were lost for several centuries, but they were fortunately recovered in the 16th Century.  He wrote the volume, Outlines of Pyrrhonism, among other works, which contrasted those thinkers he called the dogmatists, who believed they knew the truth, and the academic philosophers, who believed the truth could not be found. Sextus proposed a different methodology, that of the skeptics, who believed they had not yet found knowledge and that they should continue to search for it.  He defined skepticism in this way: “…it is an ability to set out oppositions among things which appear and are thought of in any way at all, an ability by which because of the equipollence in the opposed objects and accounts, come first, to suspension of judgment and afterwards to tranquility.”  

Sextus embraced the concept of oppositions, making it into a method.  It is important to keep in mind that there are many contemporary descriptions of agnosticism as a stance, or a concept, and of skepticism as a method, which is another way of drawing distinctions between the two philosophies.  They are very similar, but there is a difference.

Sextus’ method of oppositions was to marshal all the reasons for believing in a concept together, and then to formulate all the reasons for holding an opposite point of view, or disbelief in the concept and to put them together as well.

 Since the reasons for credence and the reasons for rejection of belief were equal, they cancelled each other out.  Because inquirers did not know which position to believe, they would end up suspending belief, which would lead to peace of mind.  Such an ameliorating philosophy was, and still is, seductive.  But note that it seems to have lost track of the original idea of the necessity to continue searching for conclusive evidence of a position. Suspension of belief that leads to peace of mind is different than the search for truth.

Sextus described different modes, or ways of arguing, explaining that he did not necessarily endorse all of them. His goal was to provide an outline and summation of arguments that were used by his predecessors during the time Phyrrhonism had flourished.  Many of the arguments he detailed concerned the relativity of human perception.  He maintained that how the world appears to us is bound up with our species. That is because our species determines the abilities we have to perceive the world, with our particular senses.  The perceptual ability of each species is limited: think of a human, a bat, and a snake. 

Sextus discussed other factors that make for relativity of perception, such as the state of our sense organs, our particular powers of discernment, whether we are healthy or sick, and how far away or near to us the objects are.

Sextus then discussed the concept of the regress of reasons.  He argued that we believe something because we have reason to credit it.  But he went on to elaborate the requirements concerning the idea of credence.  If we are to regard a concept as “adequate grounds” for belief, then we must justify that truth with a further reason and then that one with a further reason and so on. 

Tranquility would seem very far away, if such a method of reasoning were adopted and faithfully carried out. Since we humans cannot, with our limited powers of reasoning, provide an infinite regress of reasons, we will be forced to stop and come to the understanding that no claim of belief is ultimately well founded, according to Sextus.

Robin Le Poidevin explains that Sextus found other reasons that keep us from a proper apprehension of the world, such as change, motions, coming and going out of this existence, space, time and number.  Let us take up just one example that generates confusion for us- the human concept of time, which creates unsolved contradictions for people.  Time seems divided into three distinct parts- past, present and future.  But the present does not seem to be divisible into parts, as the past and future would appear to be. If the present is divisible, it will be divisible into parts of the past and parts of the future, and so will no longer be the present, which is absurd. 

However, if the present is not divisible, then nothing can change in the present, another absurdity, because we know there was and will be a change, as we have a past and a future.  Sextus concluded that we must suspend judgment.

Most important for the purposes of this lecture, Sextus turned his attention to the notion of god and human rejection of god. 

There were many attributes ascribed to god- some said he had a body and some said he did not; some said he was in some part of space somewhere and some say he was not, that he was situated out of space.  Some thinkers said god was like a human; others denied it.  Sextus concluded that since every property of god was in dispute, how could anyone claim to have any sort of reasonable conception of god?

Sextus went on to make an excellent point- thinkers could not say that god exists because if he did, then people would be in no doubt of his properties.  If we started out with something indisputable for proof of god and moved by proper reasoning or means to a conclusion, it would be obvious that god existed. To get at the truth would necessarily involve starting out with the properties of god that are disputable and use disputable means to reach a conclusion. Each move would require further support, taking researchers on the path of the aforementioned infinite regress.  Therefore, Sextus concluded, the properties of god being in dispute, thinkers would be unable to conclude the existence of god was true, and would not be able to prove or disprove his existence.

Sextus appears to have been an agnostic concerning god and god’s nature.  His thinking and modus operandi would seem to corroborate those who argue that agnosticism is a state of mind, and that skepticism is a method. 

We shall now skip several centuries forward from Sextus Empiricus to the philosopher, Immanuel Kant (1724- 1804). Please keep in mind that we have passed over many skeptics and philosophers who made use of skeptical methods, such as Descartes, for reasons of time and because some are beyond the scope of this lecture.

Please see Atheist Philosophy- Skepticism at in order to find a more thorough history of skepticism. Kant is very difficult to read, but many scholars who have studied and understood him, especially his idea of knowledge, have judged him as the greatest philosopher of all time.  Kant’s ideas did so much to illuminate how limited our human senses are to perceive reality and so much to illustrate why our reason and experience can both be flawed, that it is difficult to be critical of some of his conclusions.  

He began his work, it would seem, as a skeptic, and then became afraid of going too far.  I don’t think most secular people will be pleased with his conclusions about both god and morality.  Nevertheless, Kant is an important thinker who helped advance the skeptical stance.

His two most important works were the Critique of Pure Reason (1781) and the Critique of Practical Reason (1788).  In the Critique of Pure Reason, Kant demonstrated the serious flaws in the two dominant philosophies in Europe at that time. Empiricism was dominant in Britain, and the Continent had embraced Rationalism.  Empiricism is the idea that the source of knowledge about the world comes entirely from sensory experience, and rationalism involves claims that we are able to gain knowledge completely through the exercise of our minds.

Kant believed both philosophies were mistaken.  He explained that it is impossible for experience to be the sole source of knowledge all the time because we would be unable to interpret pure experience, even if there were such a thing as pure experience, which he believed was doubtful. Our sense organs and minds are too limited to interpret pure experience.

 So we must impose artificial, so-called “categories of thought” on experience to gain knowledge from it and such formation of categories is dependent on reason.

However, reason cannot be the source of knowledge alone because attempting to gain knowledge through reason by itself results in serious contradictions.  Kant discussed these flaws in a section called “Four Antimonies of Pure Reason” in his first Critique volume. 

Each of the four antimonies consisted of two arguments, which Kant placed side by side, with contradictory conclusions.  Employing this method, he demonstrated to the reader how people seem to be compelled to think contradictory things about the world.  The first Antimony states that we believe the world had a beginning in time, and we also believe that it did not.  The second Antimony states that we believe objects are composed of simple objects which do not have any parts at all, and at the same time, believe there aren’t such objects.  The third Antimony is that we believe we are free and also believe we are bound by causality’s laws.  The final and fourth Antimony is about god- we believe in the existence of a necessary being and at the same time, we do not believe in such a being at all.

Le Poidevin explains Kant’s conclusion that we must become aware that “knowledge is limited to objects of possible experience- the phenomenal world.”  We must recognize that the terms and thought processes we use to make sense of experiences, the structures of space and time, do not exist independently of our experience of them.  The realm that is beyond experience is the noumenal world. 

We can say little about the realm of the noumenal, except what it is not.  Otherwise, we can say almost nothing, not even if it truly exists.  It is beyond experience.”

Now this is where most secular thinkers begin to depart from agreement with Kant. According to his critique up to this point, god cannot be part of the phenomenal world because he is beyond experience.  Equally, god might be part of the noumenal world, of which our reason knows nothing.  Kant, at this juncture, might have been expected to state god is one of those structures of thought we use to understand the world. 

He has made clear that we can neither comprehend god through our empirical knowledge of experience nor through our intellect or reason.  Skeptics might be forgiven for expecting Kant to conclude with an agnostic position concerning knowledge of god or even the conclusion that god might not exist.

But Kant drew himself up, seriously so, in his second volume, the Critique of Practical Reason. Kant stated his belief that we recognize in ourselves a quality he calls the categorical imperative.  He makes a distinction between the categorical imperative and the hypothetical imperative things we believe to be the right thing to do, if we wish to achieve certain goals. 

But the categorical imperative is a singular demand, in that it requires us to do the right thing for its own sake.  Kant believed we recognize both the right course of action and our necessity to do it.  For instance, to save a life, one must not tell a lie, according to Kant, not under any circumstances.  It is this recognition of the categorical imperative each one of us possesses and that does not vary from person to person, that makes us aware of god, the divine lawgiver. 

Notice that Kant’s notion of god seems equivalent to the moral law itself, if one believes such a concept. I do not find that most people, including myself, have any intuition or knowledge of the categorical imperative we putatively possess.

Kant seems to have frightened himself with his agnostic speculations about knowledge, experience, the natural world and so on.  But he was unable to come to an agnostic conclusion about god, although he appears to have kept the notion of god’s existence confined to intuition of moral law.  He thought we cannot know god beyond our intuitive sense of the categorical imperative. 

It is very annoying to be led by such a great thinker through skeptical inquiry about so many areas of thought to find him bringing god in by way of the back door, so to speak. Kant stated that knowledge had to be abolished to make room for belief.  However, Kant’s work encouraged T. H.Huxley and others to reach agnostic positions in a later century, the 19th.  We shall be examining their ideas in a few minutes.  One cannot overlook Kant when discussing the histories of agnosticism and skepticism.  He opened up avenues he was too timid to traverse himself, for bolder thinkers than he.

David Hume (1711-1776), writing a little earlier than Kant, was much bolder.  He was the most important philosopher of the Scottish Enlightenment of the 18th Century and a crucial thinker in the development of skepticism and agnosticism. Kant found himself forced to respond to Hume’s empiricism and to Hume’s undermining of knowledge claims.  “Reading Hume,” said Kant, “interrupted my dogmatic slumbers!” Hume was never an academic philosopher, but a civil servant in London. 

 As a young man, he was denied chairs at two important Scottish universities because he had opponents who detected his anti-religious views.  However, sales of his six volume, History of England (1754-1761), made him moderately wealthy and able to devote time to his philosophic inquiries. In his Treatise of Human Nature, written when he was 25 years old, Hume barely mentioned god in passing.  But his foes were correct- Hume was anti-religious. 

Let us look at his conception of human thought processes. It will help us understand his conclusions about the human notion of causation. It was such insights which led him to question the belief that a god was the source of creation.

When we peruse Hume’s two central theses about knowledge and thought it is important to keep in mind that he was an empiricist. 

He maintained that all our ideas have their basic source in impressions.  Impressions are sensations, perceptions and emotions. Hume believed there was always a corresponding impression for every simple thought.  Simple thoughts were what he called ideas that could not be broken down into other ideas. He stated that more complex ideas are then built up by various combinations of simple ones.

Hume’s second thesis on thinking is well known, and is often called Hume’s Fork.  Hume argued that all possible objects of our knowledge can be divided into two categories: matters of fact and relations of ideas.  Statements of facts are things that reflect the state of things, such as there is a rock in the garden, it’s raining outside and so on. We can imagine a statement of fact different from the state we are observing, say, we can imagine the garden with no rock, a look outside of the window showing sun and not rain. The state of things in statements of fact can be altered- they are changeable.

Then there is the second category- the relations of ideas: two and two makes four, all single men are bachelors, and so on.  Relations of ideas are unchanging.  It is pretty impossible to think of a state of conceptual affairs in which two plus two does not equal four.  Such ideas do not concern how the world is, but the content of concepts, which Le Poidevin states we can “discern just by inspecting them.”

Hume combined two ideas, our concept formation’s dependence on experience, and the difference between matters of fact and relations of ideas to arrive at some interesting conclusions.  Hume maintained that all our reasoning about matters of fact involves cause and effect. 

We think there is a necessary connection between these two elements.  We not only think there is a connection, we believe that causes make effects happen.

Hume argued that the cause and effect thinking that we come to believe about matters of fact is not logical.  We think that causation is necessary, but necessity only belongs to relations of ideas. Causes are not necessarily or logically tied to effects. Experience inclines us to embrace causation. We hit a ball with a bat and it flies in the air.  The flight of the ball through the air when struck by a bat happens over and over. Our experience tells us that this will happen with certainty each time we repeat the action. We expect certain effects to follow certain causes, or what we believe to be certain causes.  Le Poidevin explains that one can conceive a lightning flash not being followed by the thunder the lightning causes.  So, in matters of fact, causes are not necessarily tied to the so-called necessary connection of causes and effects. The expectation of causation is merely our conclusion concerning the connection. We arrive at that conclusion by observing the same thing happening again and again.  We expect then, as a result of psychological compulsion, what we see as cause to be followed by an effect. 

We do not see our psychological propensity to assume causation, according to Hume, and not being aware of it, we project it unto events themselves.  Hume said the human mind has “great propensity to spread itself on external objects.”

Since we need to see cause, our minds move to cause as a cosmic issue.  The world exists, as does the cosmos. So we assume that something or someone caused that existence, and some of us try to explain that the cosmos was the effect of a causer.  Many people believe in god as the cause of all things.  But they have no proof other than their own subjectivity and projection.

Hume believed we have a biological propensity or habit to assume causality as well as a psychological one.  But he maintained that such thinking was meaningless and unfounded.  We can neither prove causality nor disavow it. 

If you recall my lecture on Atheist Philosophies- Logical Positivism at, you will recognize that Hume’s Fork is strikingly similar to the 20th Century philosophy of Logical Positivism.  Hume influenced Logical Positivism and the thinking of its most notable proponent, the atheist, A.J. Ayer, who maintained that discussing the nature of god was meaningless. 

Hume’s negation of causal necessity and his analysis of knowledge were not propitious for maintaining belief either in religion, or in the notion of god.  Here is Le Poidevin on the issue: “The notion of god as something really existing in the world, though not a direct object of experience, as something that exists of necessity rather than accidently, the ultimate cause of things, on which all else necessarily depends- all this is vulnerable to Hume’s view of the limits of human knowledge.” 

Hume’s attacks on religion, in his own voice, against belief in miracles, or in the voice of Philo in his Dialogues Concerning Natural Religion, (1779) are devastating to religious beliefs.

I have heard Hume described as an agnostic, an atheist and a deist.  Even though he cast doubt on the idea of a designer, he failed to close the door for others who were inclined to deism or theism.  My personal belief, shared by some thinkers, is that Hume himself was an agnostic or an atheist.  Thomas Henry Huxley called him “the parent of Kant,” and “…the protagonist of that more modern way of thinking which has been called agnosticism.”

Now we have arrived at the 19th Century, and to the thinker who coined the word, “agnostic.”

Thomas Henry Huxley, (1825- 1895), was a physician and a scientist, best known for promoting Darwin’s theory of evolution, as described in Darwin’s 1859 The Origin of Species and other volumes.  An active, pugnacious man, he was able to argue for Darwin’s ideas better than Darwin himself, who was more retiring.  Huxley was an effective public speaker and wrote many articles promoting evolution in popular magazines.  His tenacious and pugnacious defense of the concept of evolution earned him the title of “Darwin’s Bulldog.”  It is interesting that despite his tireless dissemination of evolution, he was initially resistant to the concept of gradual evolution, and more inclined to the idea of evolution occurring in jumps and starts.  Sherrie Lyons states that Huxley was somewhat skeptical about the power of natural selection to generate new species. But he did believe the concept would have sufficient evidence and be proved eventually.

It can be seen from his needing proof about evolution that Huxley was consistent with his insistence on what he believed constituted proof of a hypothesis.  His skepticism was not about natural selection or about interpretations of experimental results, according to Lyons, but very consistent with the man’s scientific approach.

How did Huxley come to coin the word “agnostic?”  There are a couple of versions, but I am going to use his own, as it sounds both logical and appropriate. 

In 1868, James Knowles, the editor of the periodical, “Nineteenth Century,” decided to form a society that would discuss theological issues with the same open mindedness as scientific societies discussed science. 

It was decided not to concentrate exclusively on theological matters, so the name, “Metaphysical Society,” was used.  The Prime Minister, William Gladstone, was a member, as were many notable scientists, philosophers and politicians. 

Thomas Huxley was a member of the Metaphysical Society, and as time went on, he observed that other members spoke about their beliefs, such as positivism, materialism, and other “isms,” with a confidence and conviction Huxley did not share.  He became aware that his philosophical stance was just that- lack of certainty. He coined the word, agnosticism, in 1869, because he decided that it was the opposite of Gnosticism. The Gnostics were a Christian sect and a threat to mainstream Christianity in its early years, if you recall from some of my early lectures.  Gnostics laid claim to elevated wisdom concerning scriptures and salvation, and Huxley believed he saw some of the same unjustified certainty in some of his theistic colleagues.

He decided he was agnostic, in other words, non Gnostic in his approach to scientific and metaphysical issues.

Huxley said that he paraded the new word immediately at a meeting of the Metaphysical Society.  But publicly, it was a number of years before he admitted that the word, agnostic, originated with him.  James Knowles was a proponent of agnosticism; and there were periodicals that promulgated the word and its philosophical tenets.   The philosophy of agnosticism was swiftly disseminated, even being discussed in religious publications; there was extensive public interest in the idea.

Richard Hutton wrote many articles on agnosticism for The Spectator, the publication of choice for England’s well-off and well-educated elite classes.

He wrote an article titled “Pope Huxley,” describing T.H. Huxley as “a great, an even severe agnostic, who goes about exhorting all men to know how little they know.”

 Huxley first used the word, agnostic, for his book on Hume, titled: Hume with Helps to the Study of Berkeley, published in 1879. In that volume, he called Socrates the first agnostic. He referred to Hume in connection with Kant and Locke, and I quote again, his observation that Hume “was the protagonist of that more modern way of thinking, which has been called agnosticism.” By that time ‘agnostic’ was common currency.  From 1869 to 1883, the use of the word had become widespread, and yet Huxley would not admit he was the originator of it. 

Huxley’s accounts or hints about why he did not come out as the originator of the word, agnostic, was his fear, that given his reputation for ungodliness, the word and concept would have met with suspicion.  At any rate, Huxley was “tricked” into giving away the information by the editor of a journal called, “The Agnostic Annual.” He replied to a query by its editor, Charles Watts, and acknowledged that he was the coiner of “agnostic.”

Huxley had apparently thought the letter he wrote Watts was confidential, but Watts published it.  Huxley was furious with Watts, but one wonders if he was not privately relieved.

Huxley soon began to face challenges on two fronts.  Church men and conservative Christians were complaining that agnosticism was a sneak attack by atheism under a different name.  But on the other front, Huxley was starting to be associated with the ideas of the philosopher, Herbert Spencer, who was arguing for the real existence of some sort of unknowable Absolute, which was sounding suspiciously like god.

The notion that agnosticism was a sort of religious, or negative creed, with articles of faith, was a vexing issue for him.

It was necessary that Huxley meet such challenges, particularly the one that agnosticism was a creed.  He wrote in “Agnosticism and Christianity, (1899), that agnosticism was not a creed of any kind. He went on to assert  “…that it is wrong for a man to say that he is certain of the objective truth of any proposition unless he can produce evidence which logically justifies that certainty.  This is what agnosticism asserts: and in my opinion, is all that is essential to agnosticism.” A bit later in the article Huxley stated: “I do not much care to speak of anything as “unknowable.” With this article, Huxley clarified the agnostic principle.

For more of Huxley’s successful struggle to take science to a position of hegemony vis-à-vis religion, please see “The Conflict between Science and Religion” at I wish to add a footnote before we move on to the different categories of agnosticism and its philosophical principles.

Thomas Henry Huxley was the grandfather of the famous humanist scientist and philosopher, Julian Huxley, of the well known novelist, Aldous Huxley, and of Andrew Huxley, a Nobel Prize winner.  Julian Huxley was the father of Francis, a prolific anthropologist and of Anthony, a prolific biologist. In his preface to Ronald Clark’s book, The Huxleys, Gavin de Beer said “…that there can be few men more religious, in the proper sense of the word, than T.H., Julian and Aldous, devoting all their energies and gifts to improving the sorry lot of men, without mummery, petitionary prayer or superstition.

In the decades after T.H. Huxley, different interpretations of the word agnosticism and of its principles had begun to change some of the tenets of the philosophy. It began to diversify into many categories, and in the present day, people who embrace several different types of doubt call themselves agnostics. Today, its definition, appears, according to Aaron Holland, “… to have reached the pinnacle of ambiguity in the philosophy of religion.” Holland goes on: “Upon survey, one will find that those who consider themselves agnostics may differ significantly in their views with respect to methodology of inquiry, the conditions for justification of belief and the limits of knowledge.  If one begins to investigate, he/she will find there is no so-called “orthodox” interpretation of agnosticism; no single set of necessary and sufficient conditions for agnosticism can be articulated.”  Holland is absolutely correct. He has identified four broad categories of agnosticism, a wide mapping of the very expansive landscape of the agnostic stance, as well as some peripheral, but still significant, categories.

By far the most common type of agnostic is the person who claims that they have no personal evidence with respect to the claims that god exists or not. 

Such ambiguity is for the most part accepted by agnostics and some atheists in the general population.  But it is quite different from the rather more modest methodological agnosticism of T.H. Huxley.  In fact, it appears to be what Holland terms “cognitive lethargy,” reluctance to consider the arguments in a serious manner concerning the pros and cons of god’s existence.

(Please see “What is Atheism- Arguments For and Against the Existence of God” at According to Holland, such agnostics seem to have borrowed the cloak of a philosophical position with none of the effort involved to arrive at their lofty position.  Critics have pointed out that such intellectually lazy people have no right to call themselves anything at all. 

Although there are those defenders who say such agnostics are on their way to atheism, it seems very doubtful that people who rest on the title of agnostic, but have not wrestled with doubt, nor undertaken a serious investigation of the issues involved, will possess the energy and conscientiousness to move into the atheist camp.  Atheism requires thinking, conviction and courage.

The second area of agnosticism has been called parity agnosticism.  It is stronger and somewhat more thoughtful than the first form of agnosticism, the personal ignorance stance.  The parity agnostic is of the opinion that all the arguments for and against god are so balanced that neither stance is preferable.  Such arguments, or rather, the parity between them, are so equivalent that a suspension of belief, they argue, is the necessary result; they maintain that knowledge of god’s existence is unattainable.  But is such a claim necessarily true?

There is a difficulty with the parity position.  It would seem that such agnostics must take the responsibility to prove that the arguments for and against the existence of god are actually as finely balanced on the scale of reason as they purport.

If the evidence for, the arguments for, one side are slightly tipped in that side’s favor, or even marginally superior to the opposite side, then the parity agnostic should be prepared to explain why suspension of belief is superior to a different belief or doubt.

Then there is the san-evidence, without evidence, agnostic, who is quite close to the parity agnostic.  However, this agnostic argues that there is no evidence for, and no evidence against, the existence of god. 

Since there is no evidence, or sufficient evidence on either side, claims the sans-evidence agnostic, neither belief nor unbelief can be adopted. The same problem exists for the sans-evidence agnostic as it does for the parity agnostic.  Are both sides so finely balanced that agnosticism is the proper stance?  In this category, the evidence or arguments for both sides must be close to zero.  I would think inquirers would find it difficult to believe that both theists and atheists have nothing persuasive in their respective points of view, which places the sans-evidence agnostic in a difficult position.  If either the parity or sans-evidence forms of agnosticism are embraced, neither type appears to be what agnosticism has sometimes been termed- as a third alternative to theism and atheism. 

Agnosticism has been described as a modest alternative to theism and atheism, but it is obvious that these two types of agnosticism have abandoned Huxley’s modest methodology.  However, neither stance can be accused of the intellectual laziness of the first type of agnostic.

Then there is the fourth category, which rests on a slippery slope.  It is a stance that many atheists and other secular people most object to when considering agnosticism.

This fourth category is not intellectually lazy.  We might, as Aaron Holland does, call it fideistic agnosticism.  Such agnostics state that there is an unknowability of the metaphysical claims to god’s existence, or non existence, but maintain that belief or disbelief is still possible.  A closer examination of such agnostics’ philosophy usually reveals an affinity with theism. Ostensibly their interpretation of agnosticism is compatible with atheism or theism. But despite their disclaimers they lean toward belief in god’s existence.  This is because religious agnostics assert that god is unknowable and this assertion allows them serious latitude when they put forward the contention that there is a god.

Agnostics such as Leslie Weatherhead, stated that they believed in god’s existence, and averred that there are limitations concerning our cognitive faculties.  Here is Weatherhead, a 20th Century Christian theologian, on the issue: “But surely, in so many matters, a reverent agnosticism is the only place where a Christian can rest his mind; remember the gap between a child’s comprehension and his father’s activities is nothing compared with the gap between the wisest man’s understanding and the scope of god’s activity.” His position contradicts the persistent claim that agnosticism is an alternative position to theism or atheism.  His notion cannot be reconciled with deism either. It is theism, disguised by ambiguity and vague explanations.

There were prominent 19th Century Protestant theologians, such as Friedrich Schleiermacher, Albrecht Ritschl, and Bishop Henry Mansel, who followed Kant and maintained the divine was unknowable.  They claimed that Christian theology was not a study of the divine, but merely described the community’s value judgments and religious feelings. But they continued to give credence to a shadowy notion of the divine, as did Weatherhead.

I shall be speaking more during this lecture concerning my objections to religious agnosticism. Such thinkers seem disingenuous.  They continue to assert the existence of a dubious divine being or absolute.  They cling to the certainty of an absolute.  Agnostics in the tradition of Huxley believe it is morally wrong to hold propositions that are not demonstrable or demonstrated. Huxley was quite firm in his conviction about evidence. Religious agnosticism is an oxymoron.

There are other categories of agnostics. Some of these categories are very close to each other or to our previously mentioned types.  Sometimes they differ by a hair or so. One type of agnostic might agree that the knowledge of god’s existence is not attainable and still disbelieve in god’s existence.  Some atheists count such agnostics as atheists, but it is not correct to place such people in the atheist camp.  Agnostics who make claims of the non attainability of knowledge of god’s existence, and then state they disbelieve in god’s existence, are trying to straddle two positions.

Such agnostics might not be taking an intellectual stance at all, but trying to avoid social stigma by playing down their disbelief and highlighting the limitations of knowledge.  They are not intellectually sincere or courageous enough to be called atheists.

 There is another type of thinker who falls into the category of philosophic naturalism. (See Atheist Philosophies- Naturalism at Such contemporary scholars eschew metaphysics. 

They might, by a very thin line, be considered atheist agnostics.  They find that metaphysical knowledge of god is unattainable and do not believe in god’s existence.

 It seems inconsistent to shun metaphysics and yet assert a metaphysical belief in god’s non existence. Such a position appears to be self-contradictory.  Why do they embrace such convoluted reasoning rather than simply stating that they are atheists?

Aaron Holland tries to mount a defense of philosophic naturalism’s agnosticism against the charges that it is self-contradictory.  He is not claiming that the position is correct, merely that it is not necessarily self-contradictory.  The entire argument is convoluted, but I think it is worth glancing at, in order to understand yet another limited version of agnosticism.  His argument is that “though it is a metaphysical claim to deny the existence of deities, it seems unreasonable to expect the philosophical naturalist to suspend belief in these cases rather than disbelieve.  This unreasonableness is clearly seen when we emphasize that agnosticism often connotes a middle place between belief and disbelief.  It is often a position held because neither side is more reasonable than the other.”  That is all well and good, but we have seen that a stance of equipoise is arguable.

It is necessary to keep in mind that agnostics cannot prove that the arguments for and against the existence of god are truly equally balanced.  There might be a marginal superiority for one side over the other. I cannot emphasize or repeat this point enough when evaluating the agnostic stance.

Let us play the devil’s advocate for agnosticism for a moment and consider the argument of philosophical naturalists. The philosophical naturalist may point out that it would be odd for someone to be agnostic about the existence of Zeus, for instance. Perhaps Zeus exists or perhaps not.

 The naturalist may agree that while knowledge of Zeus’ existence is not obtainable, that fact does not commit the thinker to a suspension of belief.  This type of naturalist can point out that belief in Zeus or any deity is part of the putatively normal belief-forming processes people in societies undergo.  So the atheistic agnosticism arising from philosophical naturalism might not be self-contradictory. Perhaps, but many atheists find these arguments to be rationalizations.  Such people are atheists who do not seem to want to admit it.  Is it the fear of social stigma, as we have already discussed?

There is yet another version of agnosticism.  This type of agnosticism argues that the unknowability of god’s existence is not conjoined with belief or disbelief.  Such agnostics are arguing in the skeptical mode. They are skeptical about knowledge of god’s existence but also claim that one must suspend belief concerning the issue.  We have already spoken of Hume’s skepticism in the lecture, but I would like to quote him several times in this section, as his comments speak to the issue.  Hume always appeared to advocate a suspension of judgment, championing neither belief nor disbelief. Like contemporary naturalists, he was a particular foe of metaphysics.

Here are Hume’s comments on metaphysics which I have already quoted in an earlier lecture, but seem quite appropriate to repeat at this point: “If we take in our hand any volume; of divinity or school metaphysics, for instance; let us ask, ‘Does it contain any abstract reasoning concerning quantity or number? No. Does it contain any experimental reasoning concerning matters of fact and existence? No. Commit it then to the flames: For it can contain nothing but sophistry and illusion.” 

Here is his conclusion from The Natural History of Religion concerning the question of a supreme creator: “The whole is a riddle, an enigma, an inexplicable mystery.  Doubt, uncertainty, suspense of judgment appears the only result of our most accurate scrutiny concerning this subject.” Hume’s stance appears similar to that of parity or sans-evidence agnostics, but his position was extremely well thought out and belongs to the skeptic school.  Most contemporary skeptics faced with the enigma of no proof for the existence of god would be, as I wrote in my definition of skepticism, more inclined to take a position of disbelief, or at the least, suspend belief rather than disbelief.

Now I would like to return to fideistic agnosticism. I laid out some of its tenets a few moments ago, and mentioned some of its most famous proponents, as well as some arguments against it.

Such religious agnosticism might, in part, be traced to another important historical figure, the aforementioned Immanuel Kant.  We have already discussed his inability to do away with the concept of god even though he vehemently denied metaphysical knowledge of any kind.  If you recall, he decided to claim the existence of god in an attempt “to make sense of our moral experience.”

While there are a few, very few, universal moral prohibitions in primitive societies, I have yet to read of one in which Kant’s categorical imperative exists.  What are we to make of claims of religious agnosticism then?

I urge those people who are not familiar with W.K. Clifford’s “Ethics of Belief” to read the essay, first published in 1877. 

Try to get the edition which has William James’, the eminent psychologist’s response to Clifford, called “The Will to Believe,” and A. J. Burger’s response to both essays, which is highly critical of James.  That particular edition is listed in the Bibliography.  W.K. Clifford stated unequivocally that the position of ambiguity is not merely mistaken, but egregious.  His essay disposed of the first type of agnostic and of lukewarm theists, the ones who might fall back on the excuse that they have no time for a prolonged inquiry into any proposition such as god or any issue that required or is proposed for our unquestioned assent. Clifford stated that if such people have no time for an inquiry they should have no time to believe.  He maintained we have a duty to inquire into any demands that we believe without being furnished with proof.

If a religious agnostic or believer admits to not knowing for certain about god’s existence, but accepts it “by faith,” Clifford believed this is a “sin against mankind.”  Anything that smacks of self –deceit and then passing that delusion to others gives rise to greater dishonesty in society.  Clifford stated that such self-deceit is a moral corrupter and presents an excellent case for his position.  He maintained: “…It is wrong, everywhere and for anyone to believe anything on insufficient evidence.”  I cannot agree more.

A slight segue here. If any secular person is somewhat confused as to whether James was a pragmatic, rather than believing, defender of religious belief, the essay in The Ethics of Belief will confirm his endorsement of religious belief.

Some scholars argue that James’ position is so nuanced that many unbelievers do not understand it properly.  I am of the opinion that such an accusation is disingenuous or perhaps self-deceitful.

James was most likely not a believer, but he was a pragmatic defender of religious belief.

I would like to continue my critique of religious agnosticism by briefly exploring the Christian position, put forth by such eminent theologians such Alvin Plantinga and Richard Swinburne. (See Free Will and Determinism and Arguments for and against the Existence of god at  Such Christians love to expound on the “hiddeness of god.” This expression has also been taken up by religious agnostics.  Theists maintain that god has placed humans, his creation, at an epistemic distance from him, so they will be able to exercise free choice. Theologians argue that this distance is important for other reasons as well, both involving so-called human freedom.  The first reason is that humans are so far from god so they will not be forced to believe in him and the second reason is so that humans will not base any of their moral choices on the desire or hope of reward.  Van A. Harvey states that such a position may be summed up as “…god is hidden to preserve both our cognitive and moral freedom to form our character for good or ill.:”

Such arguments, formulated by self-admitted theists, are disingenuous and so-called religious agnostics err philosophically when they incline to such stances. 

J.L. Schellenberg, the philosopher, has little trouble turning the notion of the “hiddeness of god” on its head.

(See What is Atheism? – Arguments for and against the Existence of God at for more refutations of Plantinga and Swinburne.)

Harvey maintains that Schellenberg has formulated a rebuttal that may be summed up as (1) If there is a god, he is perfectly loving, (2) If a perfectly loving god exists, reasonable non- belief would not occur, (3) reasonable non belief does occur, (4) so no perfectly loving god exists, (5), therefore there is no god.  Schellenberg is arguing by taking his opponents’ statements and deconstructing them.

The theistic statements embraced by its proponents demonstrate how far religious agnosticism has drifted from Huxley’s agnosticism to arguments pro and con against god’s putative hiddeness. For it is not only the theists who make such a claim, but also some s0-called agnostics who are religious.  Religious agnostics are an oxymoron, in my opinion, and I am stating this idea once again because I have very strong objections to religious belief disguising itself with the putatively lofty philosophical position of agnosticism.  The hiddeness of god notion is a stealth cover for belief, not for suspension of it.

Now I would like to turn to a revered figure in the atheist and skeptical world, the cosmologist and writer, Carl Sagan (1934- 1996.)   In his classic volume, The Demon-Haunted World, (1995)     Sagan writes of an imaginary conversation between himself and his reader.  Sagan has just told the reader there is a fire-eating dragon living in his garage.

“Show me,” you say.  I lead you to my garage.  You look inside and see a ladder, empty paint cans, an old tricycle, but no dragon.  “Where’s the dragon?” you ask. “Oh, she’s right here,” I reply, waving vaguely. “I neglected to mention she’s an invisible dragon.” You propose, says Sagan, to spread four on the floor of the garage to capture the dragon’s footprints. “Good idea,” I say, “but this dragon floats in the air.” Then you suggest you will use an infrared sensor to detect the invisible fire. “Good idea, but the invisible fire is also heatless.” You’ll then spray paint the dragon and make her visible.  “Good idea, except she’s an incorporeal dragon and the paint won’t stick.” Sagan humorously demonstrates as the story proceeds, that no matter what test is proposed to ascertain the presence of the dragon, there is a reason why the test will fail to produce proof of the dragon’s existence.

So, is it reasonable to believe that there is a dragon in the garage?  Obviously it is not, with the absence of any convincing proof.  But then Sagan confronts the reader with reports of other dragons in other garages.  When flour is spread on some of the floors, there are reports of visible footprints.  However, these footprints never seem to be visible when a skeptic is around.  There are other proofs reported about the reality of the dragon, but the results might have easily been due to other causes than the presence of the invisible dragon.

Sagan concludes: “The only sensible approach is to be open to future physical data, and to wonder what the cause might be that so many apparently sane and sober people share the same strange delusion.” 

Sagan does not explicitly compare the invisible dragon with god.  In The Demon-Haunted World, his purpose is to counter all superstition and pseudo-science with their seductive and insidious myths. He is proffering the revelatory findings of true science as a” humanizing and intelligent methodology, rather than attempting to disprove the existence of god.” 

But there is a convincing religious parallel drawn by that brilliant philosopher and atheist, Bertrand Russell (1872- 1970). In his 1952 “Is There a God?” Russell introduces an object for which there is no true evidence.  He writes: “Many orthodox people speak as though it were the business of skeptics to disprove received dogma rather than that of the dogmatists to prove them.  This, of course, is a mistake.  If I were to suggest that between Earth and Mars there is a china teapot revolving about the sun in an elliptical orbit, no-one would be able to disprove my assertion provided I were careful to add that the teapot is too small to be revealed by even our most powerful telescopes. But if I were to go on to say that, since my assertion cannot be disproved, it would be intolerable presumption on the part of human reason to doubt it, I should be equally thought to be talking nonsense.”

Le Poidevin lists several morals to be drawn from the tales of the dragon and the teapot. He lists three unexceptional ones. (1) The fact that we cannot prove that there is no dragon and no teapot does not make it reasonable to suppose that they exist. (2) The fact that we cannot prove that there is no dragon and no teapot does not make it unreasonable to suppose that they do not exist.

(3) The fact that we cannot prove that there is no dragon and no teapot does not make the likelihood of their existing equal to the likelihood of their not existing. Richard Dawkins, the atheist evolutionary biologist, draws a lesson from the third moral.

But then he moves on to create a stronger one from Russell’s teapot story, which we shall call (4) “Whereas we cannot positively rule out the teapot (and, we might add, the dragon,) with 100% certainty, it is reasonable to suppose the likelihood of its existing to be very small, or at least, much less than the probability of its existing.

For Russell himself, his idea about his teapot is (5) “The onus is on defenders of the teapot (or dragon) to establish their position.  The initial assumption, which requires no defense, is that it does not exist, and we need positive reasons to move us away from this assumption.” And now, Dawkins draws this conclusion from reading Russell: (6)” Theism is in a similar position to believe in the teapot (or dragon).  The fact that we cannot prove there is no god is a very weak argument in favor of agnosticism, that takes god’s existing to be as probable as his not existing.  And if allowing more than 0% probability to god’s existing counts as agnosticism (because it leaves some room for doubt, however little,) then we should be teapot agnostics, too.”

Dawkins conclusion is that “Russell’s teapot demonstrates that the ubiquity of belief in god, as compared with belief in celestial teapots, does not shift the burden of proof in logic, although it may seem to shift it as a matter of practical politics.

That you cannot prove god’s non-existence is accepted and trivial, if only in the sense that we can never absolutely prove the non-existence of anything.  What matters is not whether god is disprovable, (he isn’t) but whether his existence is probable. 

That is another matter.  Some undisprovable things are sensibly judged far less probable than other undisprovable things. 

There is no reason to regard god as immune from consideration along a spectrum of probabilities.  And there is certainly no reason to suppose that just because god can neither be proved nor disproved, his probability of existence is 50%.”

Another excellent atheist writer and thinker who criticizes agnosticism is George H. Smith.  His volume, Atheism: The Case Against God, (1974), is a much read and convincing classic.  In his text, Smith argues that agnosticism is not a suspension of belief but a variation of either atheism or theism.  It only emerges, he argues, as a third alternative between atheism and theism if atheism is given the narrow definition as the denier of theism.  But Smith states: “We have seen that atheism, in its broadest sense, refers basically to the absence of a belief in god and need not entail the denial of god.  Any person who does not believe in god, according to Smith, for whatever reason, is without theistic belief and therefore qualifies as an atheist.”

Smith argues that the Huxley variety of agnostic really does not believe in the existence of god.  Smith thinks that if a person did believe in the existence of god, he would of necessity be a theist, although according to other writers he could be a religious agnostic. 

Smith would deny that this is a cogent category and he would be correct. We have already seen that the term religious agnostic is an oxymoron.

Smith goes on to reason that “while an agnostic of the Huxley variety may refuse to state whether theism is true or false, thus suspending his judgment, he does not believe in the existence of a god.  (If he did believe, then he would be a theist.) 

Since this agnostic, Smith argues, does not accept the existence of god as true, he is without theist belief; he is atheistic, and Huxley’s agnosticism emerges as a form of atheism.  Smith has developed a salient argument, but I doubt if Huxley would agree.

Following from the above premise, Smith maintains that agnosticism is not an independent position, a middle way between atheism and theism.  He holds this position, he argues, because agnosticism classifies according to different criteria than both atheism and theism.  Smith explains that: “Theism and atheism separate those who believe in god from those who do not.  Agnosticism separates those who believe that reason cannot penetrate the supernatural realm from those who depend on the capability of reason to affirm or deny the truth of theistic belief.”

Smith argues, and I believe he is correct, that the agnostic theist encounters opposition not only from atheists, but from theists who believe the attributes of god can be at least partly known by the human mind.  The agnostic atheist is opposed by atheists who do not accept the possibility, even the theoretical one, of the existence of a supernatural being. Atheists usually maintain that reason can demonstrate that belief in such a being is false or at least nonsensical.

Smith points out that some unbelievers use the term, agnostic, to describe themselves in order to dodge the stigma of being regarded as an atheist.  We have seen this criticism leveled at agnostics earlier in our lecture, and I think that it has validity.

Such agnostics like the fact that its vagueness “has earned agnosticism the status of an intellectually respectable form of dissent from religion.”

While Smith thinks that agnosticism is a genuine, if mistaken, philosophical position, he states that it is not a middle point between atheism and theism.  It can be seen as a variation of atheism or theism.  Self proclaimed agnostics who make claims whether or not they believe in god, by the very act of choosing their proclivity to one stance or another, have committed themselves either to atheism or theism. Smith argues that such individuals are in an indefensible position when they attempt to cling to their convenient escape clause of agnosticism.

I have not yet mentioned the contemporary philosophers who make the case that the arguments for and against theism, atheism and agnosticism have very little to do with the way our belief systems are formed.  Van A. Harvey explains that they argue that we do not weigh the evidence or think through every proposition offered us.  Beliefs are seldom offered, they say, but are culturally taught, or at least the organizational habits become ingrained in us, by means of rules, conceptions, names, and so on.  We receive such propositions, which are not really based on empirical research or evidence, by virtue of belonging to a community that is bound by education and science, but also by misconceptions, superstition, outworn cultural values and the like.

All of these elements and more go into our picture of the world, the one that we frequently begin to believe in. 

We have, in the words of the philosopher, Martin Heidegger (1889- 1976), been “thrown” into a culture at birth, where geography, language and other factors influence and often keep us from maturing beyond its limitations.

But for some of us, doubt begins.  Sometimes we find ourselves entertaining beliefs that are contradictory, in their terms and consequences.  Sometimes we begin to survey other ideas whose terms or tenets contradict our received pictures of the world.  Some of us, who begin in belief, make a breakthrough and end in doubt.

Van A. Harvey suggests that it is possible that many agnostics have reached a certain point where they no longer believe in many of the propositions, customs, and beliefs of their communities, which are bound, in the West, by education and science. Here are my paraphrases of Harvey’s thoughts on this issue.  Perhaps agnostics feel they cannot correctly assess the totality of received opinion.  Sometimes they decide to live as rationally as possible, but within the limits of their communities’ assumptions and beliefs.  Such agnostics may wish to keep their minds free from nostalgia for the past and from clinging to absolutes, such as belief in a deity.  They accept the relativity of their own and their community’s position in history and do not go beyond the limits set by education and science, even though they are aware that what seems reasonable belief and behavior may in the future come to be seen as erroneous.  

This lengthy speculation of Harvey’s on agnosticism lends credence to the claim that agnosticism is the very complex issue I maintained it was when I began this lecture.

I would like to close with the words of the man labeled as “The Great Agnostic.” Robert Ingersoll (1833- 1899) was the proponent of free thought who lectured and wrote tirelessly, promoting secularism in the United States during the 19th Century.

He made both secularism and free thought popular. (For more information on the eminent secularist, Ingersoll, please see Atheist History- American Atheist History at

Ingersoll stated that: “…an atheist is an agnostic and an agnostic is an atheist.”  We have learned that the issue is more complex than Ingersoll believed.  However, Ingersoll is most important because whether an atheist or an agnostic, he was a secularist.  Tom Flynn states that Ingersoll was “…a man of substantial beliefs- beliefs devoid of supernatural content but rather having profoundly to do with justice, reason, the Enlightenment, and the fruits of science.” He went beyond the limits that bound many minds and lives and that is what contemporary atheism and agnosticism need to strive for.  We must try to pass beyond our cultural truisms and expectations.

I would like to close with the words of Ingersoll on secularism.  It is a wonderful statement on the actions inspired by free thought to achieve freedom in our lives and communities.

“Secularism is the religion of humanity.  It embraces the affairs of this world.  It is interested in everything that touches the welfare of a sentient being; it advocates attention to the planet on which we happen to live; it means that each individual counts for something; it is a declaration of intellectual independence, it means the pew is superior to the pulpit, that those who bear the burdens shall have the profits and they who fill the purse shall hold the strings.

It is a protest against being the serf, subject or slave of any phantom or the priest of any phantom.  It is a protest against wasting this life for the sake of one we know not of. It proposes to let the gods take care of themselves…It is living for ourselves and each other, for the present instead of the past, for this world instead of another…It is striving to do away with violence and vice, ignorance, poverty and disease…

It does not believe in praying and receiving, but in earning and deserving…It says to the whole world, Work that you may eat, drink and be clothed; work that you may enjoy; work that you may not want; work that you may give and never need.”

 Ingersoll’s words bring this lecture down to earth, the earth of striving, the earth of realizing hopes by action and away from the intellectual distinctions we have concentrated on during this lecture.  They were necessary to learn, but there is vital, unfinished work that the secular community needs to dedicate itself to, which goes beyond the difference between atheists and agnostics. 

I hope, after hearing the words of men like Robert Ingersoll and T.H. Huxley and reading about their lives and accomplishments, that the secular community, atheists, agnostics, freethinkers and skeptics, will resolve to join together to form one large society of enterprise and thought dedicated to human flourishing and to freedom of people from poverty, from superstition, from religion and from oppression everywhere.

Video of Lecture: Agnosticism

Lecture: Agnosticism

Video of Discussion: Agnosticism

Discussion: Agnosticism


There are more references in the bibliography of the lecture titled: What is Atheism: Arguments For and Against the Existence of God

Burger, A.J., Ed.  The Ethics of Belief: Essays by William Kingdon Clifford, William James, A.J. Burger. Rev. Ed. n.p.: Publisher’s Cataloguing-in-Publication Data, A.J. Burger, 2008.

Darrow, Clarence. “Why I Am an Agnostic.” Amherst, New York: Prometheus Books, 1995.

Dawkins, Richard. The God Delusion.  Boston; New York: Houghton Mifflin Company, 2006.

Flynn, Tom and Roger E. Greeley. “Robert Green Ingersoll.” In Tom Flynn, Ed. The Encyclopedia of Unbelief. Amherst, New York: Prometheus Books, 2007. 423-427.

Harvey, Van A. “Agnosticism and Atheism.” In Tom Flynn, Ed. The Encyclopedia of Unbelief. Amherst, New York: Prometheus Books, 2007. 35-40.

Hecht, Jennifer Michael. Doubt: A History.  New York: Harper Collins, 2004.

Holland, Aaron. “Agnosticism.” In Tom Flynn, Ed. Amherst, New York: Prometheus Books, 2007. 33-35.

__________. “Consistency in Presuming Agnosticism.” Philo 4 (2001).

Huxley, T.H. Selections from the Essays of T.H. Huxley. Alburey Castle, Ed. New York: Appleton-Century-Crofts, 1948.

Jacoby, Susan. Freethinkers: A History of American Secularism. New York: Henry Holt and Company, 2004.

__________. The Great Agnostic: Robert Ingersoll and American Freethought.  New Haven and London: Yale University Press, 2013.

Le Poidevin, Robin. Agnosticism. Oxford, New York: Oxford University Press, 2010.  This volume contains an excellent and thorough Bibliography.

Lightman, Bernard. The Origins of Agnosticism: Victorian Unbelief and the Limits of Knowledge.  Baltimore: John Hopkins University Press, 1987.

Lyons, Sherrie. “Thomas Henry Huxley.” In Tom Flynn, Ed. The Encyclopedia of Unbelief. Amherst, New York: Prometheus Books, 2007.  410-411.

Schellenberg, J. L. Divine Hiddeness and Human Reason. Ithaca, New York: Cornell University Press, 1993.

Smith, George H. Atheism: The Case Against God. Amherst, New York: Prometheus Books, 1989.

Tanis, Edis.  The Ghost in the Universe.  Amherst, New York: Prometheus Books, 2002.