History of Skepticism:
Skepticism has a long history dating back to the 5th century B.C. with the sophists and to the 4 century B.C. with the Pyrrhonians.[1] This article will look at these two ancient forms of skepticism for historical context and then look at four different versions of modern skepticism.

Ancient Schools of Skepticism:
Two main schools of skepticism thrived in the 5th and 4th centuries BC: Academic skepticism and Pyrrhonian skepticism.

    I   Academic skepticism has two main assertions:[2]
        1.  The skeptical thesis: all things are inapprehensible; therefore, no one has any
            knowledge.
       2.  Pertaining to the skeptical thesis: the skeptic dogmatically affirms that we know
            that no one has any knowledge. (italics mine)

   II  Pyrrhonian skepticism's two main assertions:[3]
       1.  Reject dogmatism.
       2.  Suspend judgment about all things including the skeptical
            thesis (Academic skepticism's first assertion).

Digging Deeper into Ancient Skepticism:

Academic Skepticism (AS):
Assertion 1
Academic skepticism (AS) has some difficult obstacles to overcome. Notice that the skeptical thesis (namely, all things are inapprehensible; therefore, no one has any knowledge) is something that can, supposedly, be know (even though it claims no one has any knowledge, emphasis mine). If this is correct, it is hard to see how the skeptical thesis could be known by the skeptic since this is a claim to knowledge while, at the same time, we are not suppose to have any knowledge! As such, the AS would have a hard time even getting off the ground.

However, it could be that the skeptical thesis (ST) actually claims to have one piece of knowledge, namely, that all things are inapprehensible; therefore, no one has any knowledge.[4] In other words, the ST is the single piece of knowledge a person has. But, if this is the single piece of knowledge one has, then it becomes problematic because to say “all things are inapprehensible” other than the ST implies that the skeptic knows that there is more than one thing to know (more than simply the ST). But, according to the ST, the only thing known is the ST. Therefore, the ST appears contradictory.

It seems that no matter which interpretation one takes of the ST the AS position is untenable.

Assertion 2
As one considers the second assertion of the AS (namely, the skeptic dogmatically affirms that we know that no one has any knowledge [emphasis mine]) it becomes apparent that this is simply self-refuting. To dogmatically affirm that one knows that no one can know anything is contradictory. One simply has to ask, “How can one know ‘no one has any knowledge?’” Since, according to the AS, this is unknown, no one can know this.

The second assertion is a claim to knowledge while at the same time claiming that no one has any knowledge. This seems more like a bullheaded belief than a sound one. Due to its self-refuting nature, AS should be abandoned.

Pyrrhonian Skepticism (PS):
Assertion 1
Pyrrhonian skepticism’s (PS) first assertion is to reject dogmatism. If the PS assertion (reject dogmatism) is to be taken seriously, then it too seems dogmatic. If so, it is hard to see how dogmatism has been rejected. Dogmatism has simply been refocused and still accepted rather than actually rejected. Instead of being dogmatic that we can know our own thoughts, the PS is dogmatic that we should not be dogmatic. This glaring problem continues to plague many skeptics today.

Assertion 2
PS’s second assertion is to suspend judgments about all things including the skeptical thesis.[5] This results in an agonistic view (the belief that a view can be neither proved nor disproved) about everything. It seems difficult to see how this can actually be lived out. For instance, how is a mother supposed to suspend all judgment when she sees her young son drowning? Or, how is a jury supposed to be agnostic about the guilt or innocence of a murderer, especially with overwhelming evidence?

While suspending judgment can be noble at times (the jury should suspend judgment prior to hearing all evidence from both sides), suspending judgment is not a doctrine that can be easily or effectively lived out. However, a more subtle problem arises with the PS assertion that all judgment should be suspended about all things including the skeptical thesis. This view is itself a judgment that is not suspended. Therefore, one is left doing the very thing that one is not suppose to do: make a judgment. 

Skepticism Today (Modern Skepticism):
Today there are four basic forms of skepticism.

1. Iterative skepticism: the skeptic simply responds to each assertion with a question like, “How do you know?” but usually fails to provide an argument on behalf of his view.[6]

2. Global skepticism: the skeptic claims that there is, “no knowledge…in any area of human thought.”[7] (similar to Academic Skepticism, see above)

3. Local skepticism: the skeptic agrees that there is knowledge in some areas of thought (e.g. in mathematics or in science) but denies knowledge is possible in other areas of thought (e.g., religious knowledge, ethical knowledge, etc.).[8]

4. Methodological (heuristic) skepticism: the skeptic uses questions like, “how does one know that X” as a guiding principle as an aide to understanding issues of how one knows something.[9]

Digging Deeper into Modern Skepticism:

1. Iterative Skepticism (IS): this skeptic simply responds to each assertion with a question like, “How do you know?” but usually fails to provide an argument on behalf of her view.

This is a very common approach to a wide variety of subject matters. This skeptic attempts merely to question other views but offers little sound argumentation in return. For example, not to long ago I was talking with a friend, Vanessa, about Neil Armstrong’s lunar landing. Though she once held that he landed on the moon, due to the observations of one of her friends Vanessa no longer believes that Armstrong, or anyone else, made it to the moon. She went on to explain some of the reasons as follows:

1. If someone landed on the moon, why has no one been back?

2. The difficulty of getting to the moon is too great and, with the limited technology available in the 1960’s, it is unlikely that a person landed on the moon.

3. The landing was probably a fabrication inspired by the United State’s need to be first in the space race.

4. There are too many other unanswered questions that make believing in the lunar landing possible.

This is a typical example of the iterative skeptic (IS) tradition. The goal is to raise questions that challenge the issue at hand and then to use the doubt created by this method as a means to draw the conclusion that the view is wrong. This means that if a person is unable to answer all of the questions raised by the IS, then the IS is right by default. In other words, the IS does not actually need to prove her case. Rather, she need only to question the other person by asking questions akin to, “how do you know?” until the opponent is unable to answer and then the IS wins…. Or so she would think.

There are several pitfalls to the IS position.
First, there seems to be an assumption that all (seemingly) relevant questions must be answered before one can say that he actually knows something. In other words, Bob cannot know that Neil Armstrong actually made it to the moon unless he first has a reasonable response to the challenges above. This is because, even if the issues raised by the IS seem far fetched (and some are), they must be reasonably and decisively answered before Bob can conclude that Armstrong made it to the moon.
Let’s look at the four issues above that call into question Armstrong’s moon landing as our working example for the IS and how to work through this tactic. 

Objection 1: If we had made it to the moon, why have we not been back?
This is a typically deceptive question for those who are not lunar savvy. First, the goal is to distract the other person from all of the evidence in support of the Apollo 11 lunar landing. Evidence like: Armstrong’s testimony of having been there (is he a liar?), returning with moon rock (some 48 lbs.), testimony of the second man to land on the moon with Armstrong (Edwin “Buzz” Aldrin), unaltered video clips and photos of their presence on the moon, the American flag still on the moon, and more. Simply put, the question about why no one has been back has no bearing on if anyone has been there in the first place. This kind of question tends merely to confuse the issue, which is a common skeptical tactic. The skeptic likes to hide in doubt and confusion for these are the blankets that keep the skeptic warm.

      Second, it must be noted that this question is also very misleading since it is implying that no one has been back to the moon, which is historically erroneous. In fact, not only has the US been back to the moon multiple times (Apollo 12, 14, 15, 16, and 17 all set a man on the moon) but the Soviets also put men on the moon. Thus the first seed of doubt is based on false information.

Objection 2: The difficulty of getting to the moon is too great and, with the limited technology available in the 1960’s, it is unlikely that we landed a person on the moon.
This is true. There were an untold number of issues that had to be overcome before a person could land on the moon. However, just because the odds are against it, and the odds were definitely against it, does not mean it did not happen. This argument only brings up the difficulty of making it to the moon and avoids discussing the evidence supporting the event. What are the odds that someone would get the license plate number that she has? Yet, that is the one possessed (think about your license plate number and the odds of having it). Just because the odds are against it does not make it impossible. The odds of being able to make a fully loaded 747 fly (over four hundred tons for current versions) are high, but it hardly follows that it has not happened.

Objection 3: The landing was probably a fabrication inspired by the United State’s need to be first in the space race.
This is the classic “conspiracy theory” stance. The major problem with this is that the IS provides no real evidence (and usually no evidence at all [remember, doubt is not evidence]) against the lunar landings. Nor does the IS supply any real evidence for the conspiracy theory. Additionally, this thinking simply ignores the weight of evidence for the lunar landings. A real argument cannot ignore known evidence, it must deal with it. [A more recent example of the “conspiracy theory” happened with the first beheading of an American in Iraq during the US led occupation. The beheading was said to have been made up to help get Arab support. Naturally, no real evidence was given for this conspiracy theory. Additionally, when more beheadings happened this theory subsided but with a noted lack of conspiracy theorists saying that they were wrong.] 

Objection 4: There are too many other unanswered questions that make believing in the lunar landing possible.
This is probably true but the IS must present them and also provide a good answer to the evidence in support of the lunar landings. Otherwise, the IS has not done anything to advance the argument for her position or against the lunar landing.

The IS seems to believe that it is intellectually virtuous simply to raise questions to challenge someone else’s belief without providing many, if any, sound arguments for her own beliefs. While questions are an integral part of intellectual integrity (see methodological skepticism below), IS is hardly an intellectually virtuous stance. We need to make sure that such mind-games are rewarded accordingly. 

2. Global Skepticism (GS): the global skeptic claims that there is, “no knowledge…in any area of human thought

Global skepticism (GS) is similar to Academic Scepticism (see above). The basic problem is the apparent self-refuting nature of this position. To claim that there is no knowledge in any area of human thought is saying, “We know that we have no knowledge.” Such a claim is itself a claim to knowledge. How can one know that one does not know anything? The skeptic does not know! Thus, it seems absurd to embrace such a view. 

3. Local Skepticism (LS): the local skeptic agrees that there is knowledge in some areas of thought (e.g. in mathematics, in science, etc.) but denies knowledge is possible in some specific areas of thought (e.g., religious knowledge, ethical knowledge, etc.).

One striking problem with LS arises due to the fact that many of the challenges used to claim that religious knowledge (for instance) is not possible also affect other areas of knowledge that the LS typically embraces. As an example, one common charge against being able to know if God exists is that there is no empirical evidence for His existence. Assuming this is true, this same challenge can be leveled at other areas of knowledge. There is no empirical evidence for the existence of numbers, laws of logic, the mind, and morality (like justice or injustice, love or hate, etc.). This puts the LS in a quandary: how can the LS accept knowledge in one area (laws of logic, numbers, etc.), which have no empirical evidence supporting them, and then claim that the lack of empirical evidence is sufficient to reject knowledge of God’s existence?

Ironically, the philosophical analysis of such issues by the LS (and others) also lacks the same empirical grounds demanded by the LS for knowledge in other areas. In other words, the LS has a hard time being consistent in applying criteria for knowledge. Naturally, the solution lies in realizing that it is incorrect to assume an empirical standard of test for knowledge for non-empirical items. The test for truth must be content specific.  

4. Methodological (heuristic) Skepticism: the methodological skeptic uses questions like, “how does one know that X” as a guiding principle as an aide to understanding issues of how one knows something. This is the right approach as long as 1) the motives are right (seeking truth) and 2) the truth is accepted regardless if we like it or not.

Main Arguments For Skepticism:[11]
Today, many people are skeptical regarding many issues, especially in reference to God and morality. Doubt is the weapon of choice and some use arguments to support their skeptical approach. Following are three of the main arguments used to justify skepticism.

1. Argument from error: Since we have been wrong in the past, we might be wrong now.

Everyone one has, at one time or another, been wrong about what she believes. For instance, Becky believes that she sees Jane walking down an aisle in the store and goes over to her to say “Hi” only to find out that it is not Jane. Since everyone has been wrong on occasions in the past, it is possible that we are wrong about other things we believe. Since it is possible that we are wrong in what we believe, we cannot legitimately say that we “know” anything. Thus, the skeptic often responds to claims of knowledge by saying something like, “But isn’t it possible that you are wrong?” Once the other person agrees to this, the skeptic has, seemingly, proven her position and defeated the opposing view.

2. Brain-in-a-vat argument: It is possible that we are simply brains in a vat and not really living the lives we believe we are living.

This argument has been around for a long time and comes in different forms. Another common form is the Evil Demon argument. Either version has the same basic conclusion: that we are not living the lives we think we are living. The argument proceeds like this: it is possible that we are nothing more than brains-in-a-vat with a mad doctor manipulating what we “experience” (think of the Matrix series of movies). This being the case, we are actually wrong about everything we believe since we are not really experiencing what we think we are.

The Evil Demon argument is similar. The difference is simply that a demon has control of our minds and is manipulating our thoughts so that we think we are experiencing certain things but, in fact, we are not.

3. Transferring justification: even if we are right about our present experiences that does not mean we are right about things outside of our present experiences.

For instance, the skeptic may grant that we can have knowledge regarding certain sensory experiences (like seeing a brown dog). However, this does not mean that we are also justified in believing that the same brown dog is still alive an hour later (for it may have been killed by a car, simply ceased to exist, etc.). Therefore, the only knowledge one has is that which is available to the person at the present moment.

A Critique of the Main Arguments For Skepticism:

1. Argument from error: we might be wrong.

It is true that for any given belief one might be wrong. But this is hardly the entire story. Could it not also be said that one might be right? To say that one might be wrong actually makes little progress (because, as noted, the person might be right). To advance the argument (to actually make progress in the discussion) one needs to go beyond this simple stalemate.

For example, if the skeptic were to ask the theist if he might be wrong about God’s existence, the theist can safely answer “yes” without any real threat to theism. To see why this is so one need only ask, “What follows from the point that the theist ‘might’ be wrong?” Nothing follows from this point. This is because the converse is true as well, namely, the theist might be right. The theist can ask the atheist the same question, “Is it possible that you are wrong?” To be consistent and honest the atheist must say “yes.” But does this prove theism? No. Does this disprove atheism? No. More is necessary than this simple question.

At this point the discussion is at an intellectual stalemate, which is neither support for nor against belief in God. What this provides support for is the need to find out which view enjoys the best support (or, more appropriately, which view is more likely than its converse).

If one of these two options has more compelling evidence in its favor, then one would be prima facie justified to believe it. In other words, if theism has more compelling evidence (in the form of arguments, historical evidence, etc.) in its favor, then one is, at least initially, justified in believing that God does exist. Conversely, if atheism has more compelling evidence (in the form of arguments, etc.) in its favor, then one is, at least initially, justified in believing that God does not exist. But note that the issue does not revolve around if one “might” be right but around which view the evidence best supports. This puts the skeptic in the position of having to draw a conclusion, something many skeptics seem to resist.

This means that arguments for God’s existence (ontological, axiological, teleological, historical support, Biblical support, etc.) all weigh in to provide good reasons to hold to theism. The skeptic would need to get beyond merely “you might be wrong” and provide sound reasons for rejecting theism. In other words, the skeptic has a burden of proof too. The challenge “you might be wrong” can hardly be considered as evidence against theism.

Might – Logical and Epistemic:

What is happening in this scenario is that the skeptic is using might in a way different than others usually use it. When the skeptic claims that you might be wrong, this is a logical might. That is to say, it is logically possible that you are wrong. In other words, the possibility exists (logically speaking) that you are in error. For instance, if one were to say that China has the largest population of any country it would be logically possible to also say that China might not have the largest population. In other words, it is logically possible that another country has the largest population. This is because the logical might is basically considering all possible options and is not designed to draw a conclusion based upon evidence. Rather, the logical might is useful for finding out all of the necessary information so that a properly reasoned conclusion can be drawn. This leads us to the epistemic might.

Another use of might is the epistemic might (epistemic basically means "involving knowledge"). This means that there is good reason to believe that one view is right/wrong. If one asserts that Cameroon, Africa is the most populated country, it could be reasonably said that this is wrong due to sound reasons (namely, Cameroon is a country of only a few million while China is a country of a several billion). Thus, the belief that Cameroon, Africa is the most populated country runs into problems.

Thus, the logical might is used to be open to alternate views being correct. The epistemic might is used to draw a conclusion based on good evidence. Here is a comparison between these two might's:

Notice that the logical might presents no problems in asserting either side of an opposing view. One can rationally state both “China might be the most populous nation on earth” and “China might not be the most populous nation on earth.” Both of these assertions can be made without contradiction because both assertions are, technically, possible. However, and this is important, this is all that can be said at this point using the logical might. It is when proper supporting factors are considered that one moves to the epistemic might. Once the evidence is weighed (census of both nations shows that Cameroon has a population of approx. 16 million while China has a whopping population of a approx. 1.3 billion), one of the positions is usually seen as more plausible or supported than the other (or others).

The epistemic might is very useful for finding good grounds for accepting, or rejecting, beliefs. To linger in the arena of the logical might is to confuse possibilities with actual facts. It is necessary to move from the logical might to the epistemic might by looking into relevant data/evidence.

Hidden in the skeptical view is the belief that, in order for one to have knowledge on a particular issue, there must be complete certainty. That is to say, in order for one to know something is true there must be absolute certainty about the belief with no possible way for it to be wrong. This is simply false. There is often the “possibility” of being wrong (logical might) when one is in fact correct. The evidence is used to decide which view (or views) is correct. Even if one is wrong at times, and this happens often, it is not valid to conclude that knowledge is not possible at any time. This is because, while people are wrong from time to time, it is also true that people are right as well. Most people are right about their age, phone number, where they live and work, who they are married too, etc. While confusion may arise occasionally, this does not warrant a skeptical stance every time. It only means we need to take care in our conclusions.

2. Brain-in-a-vat argument: It is possible that we are simply brains-in-a-vat and not really living the lives we believe we are living.

As the Oxford Dictionary of Philosophy states the argument:
“We are invited to consider the sceptical possibility that our experience is actually produced by a brain suspended in a life-preserving medium (a vat) and stimulated electrically in such a way as to give us  the delusive experience of living the life with which we are familiar.”[12]

This argument is based on the use of the logical might; it is logically possible that we are simply brains in a vat.

Since we might [the logical possibility exists that we might] be brains in a vat (i.e., there is no logical contradiction in saying that we are simply brains in a vat hooked up to a computer that is inputting the images in our minds), then it follows that we might be wrong about everything we believe. Therefore, we cannot know anything (for everything we believe would be then false[13]).

The skeptic believes that with the admission produced by the logical might, skepticism is sustained and other views are rendered basically useless.

However, this is not the entire story. As noted in the previous section (“1 Argument from error.”) the converse can be stated, namely, that it is (logically) possible that we do live the lives we envision. To be fair, the skeptic would have to give just as much credence to this possibility as her own. Thus, there is more of a stalemate involved in this discussion than any real defeating of a view.

What needs to happen at this point is to move from the logical might (mere possibility) to the epistemic might (what view does the evidence seem to best support). In other words, move from the stalemate of both views being possible to finding out which view has the better support. For instance, of what we know (or think we know), is there any evidence to suggest that we are brains in a vat? What would such evidence look like? How would we tell if this was so? While it is still logically possible that we are merely brains in a vat, there does not seem to be any evidence for us to hold to this view, even if it is true.

Additionally, there seems to be strong evidence (intuition, sensory experiences, logic, etc.) that we do, indeed, live the lives we believe we have. With support for genuine lives and little, if any, evidence to the view that we are brains in a vat (including the self-refuting nature of the argument), we can safely conclude that we are not brains in a vat.

If we are simply a brain-in-a-vat and everything we believe is an illusion, then thinking that we are a brain-in-a-vat is an illusion too. Therefore, this view seems to defeat itself. 

3. Transferring justification: even if we are right about our present experiences, that does not mean we are right about things outside of our present experiences.

The skeptic could grant that we do know some things: that I am eating breakfast, that there is a computer in front of me, etc. However, even if we are justified in some things, this justification does not transfer to other beliefs. For instance, I may believe that there is a computer in this room right now (because I am using it), but that does not mean I would be justified in believing it is there an hour after leaving the room (because someone may have moved it to another room, etc.).

However, the problem with this view is that, even though a particular conclusion (that the computer is still in this room an hour after leaving the room), does not  necessarily follow from the premise, this does not mean that I cannot know it to be true. For instance, maybe I left the room, locked the door and am the only one with a key. It is possible that someone broke in and stole the computer or that a demon removed it from the room, but experience does not seem bear this out. Rather, the simpler, more straightforward belief seems most likely and holds the best support. Therefore, I can have enough certainty that it is still true until other evidence comes along to undermine the belief, even if this undermining does happen from time to time (there are times when someone does break into our homes and steal things like computers). Most often, though, the computer remains in the room untouched by either the robber or demon.  

Summary of Skepticism:
At its core, skepticism is, "the refusal to grant that there is any knowledge or justification."^[14] Skepticism rejects the idea that truth can be known.^[15] In other words, skepticism claims that we cannot know anything.

Skepticism is characterized by the refusal to admit we can know something. This refusal is especially strong when it comes to truth, God, Scripture, Jesus Christ and many ethical issues (abortion, monogamy, sexuality, etc.). While claiming to seek truth, skeptics tend to use questions as a means to hide from it and maintain their own views. The direction of their questions usually goes in the way of trying to find reasons to reject God (or, at minimum, to refuse to listen to Him). This tactic is a distinguishing mark of skeptics, as opposed to the quality pursuit of seeking truth.

Additionally, skeptics confuse "challenging" a view with "rejecting" a view. To challenge a view through asking key questions is a good manner of seeking truth. But looking for reasons to reject a view without seeking solid reasons for doing so is not an intellectually virtuous approach.

Conclusion:
Skepticism enjoys a long history (5^th century BC onward) and can presently be found in four basic forms (Iterative skepticism, global skepticism, local skepticism, and methodological skepticism). With iterative skepticism the skeptic simply replies with “How do you know?” while failing to provide sufficient grounds to undermine her opponent or support her own view. Global skepticism is the view that no one has knowledge in any area of human thought. Such a knowledge claim is strikingly self-refuting. On the local skeptic approach, the skeptic agrees that knowledge is possible in a few areas of knowledge (e.g., mathematics, logic, etc.) but denies that knowledge is possible in specific areas of knowledge (e.g., religious knowledge). The local skeptic is hard pressed to provide support for knowledge in limited areas like mathematics while rejecting knowledge in an area such as religious knowledge since many of the same criteria used to justify mathematical knowledge is used to justify religious knowledge. The methodological skeptic’s approach is the appropriate position when seeking knowledge. This position uses questions to find out the fact of the matter on the given issue while not attempting to hide from it.

The three main arguments for skepticism are: 1) argument from error, 2) brain-in-a-vat, and 3) transferring justification. The argument from error does not succeed since views are also correct. Simply being wrong at times does not guarantee being wrong every time. The brain-in-a-vat argument fails to be convincing since we intuitively do not hold to this nor have any supporting evidence for it. Additionally, if we are a brain-in-a-vat and all that we believe is an illusion, then this would also be an illusion and therefore false. Transferring justification argues that the justification of knowledge about present experiences does not transfer to knowledge that is not present to us. This view assumes that present justification is the only type of legitimate justification for a belief, which is not warranted. The view, itself, is not sustained by a present experience and is, therefore, open to its one critique.

Speaking with a Skeptic:
Talking with someone who is skeptical about an issue can be one of the most enjoyable and rewarding discussions. It can also be one of the most frustrating…and not because the skeptic says something worth listening too.

When speaking with a skeptic it is important to make sure she presents her skeptical case and is not allowed to simply raise questions that go nowhere. She needs to state why she is skeptical and what it is that she is having a hard time believing. If the skeptic is allowed to simply ask questions in the iterative skeptic tradition, then she may end up with the false impression that her questions are successful. Additionally, it is important to distinguish between the logical might and epistemological might. These different uses of this term are crucial in discussions with a skeptic. Failure to understand there proper use often results in the skeptic’s view being given much more weight than it is due.

If the skeptic is sincere with her questions and open to learning (as we need to be when skeptical about issues), the Christian is presented with a golden opportunity to give good answers regarding the Christian faith and our salvation found in Jesus Christ (1 Peter 3:15; Acts 4:10-12). The questions that arise from the skeptic need to be warmly embraced, thoughtfully considered and intelligently answered. Often this is a good opportunity for the Christian to grow in her faith as she seeks quality answers to sincere questions. However, it is imperative for the Christian to avoid common pat-answers like “just believe.” It is our responsibility to help others come to understand who Jesus Christ is and to accept Him as Lord and Savior. These steps are different for each person and need to be tailored accordingly.