In our first essay , I described the nature of philosophical questions and the attraction that they have on us.  We find our way to philosophy in the midst of ordinary life.  Ordinary practical problems lead us to more general, more fundamental questions.  One of the most prominent paths from the ordinary to the philosophical is via doubts and uncertainty.

It is hard to imagine a thoughtful person who is not troubled, on occasion, by some form of doubt or skeptical worry.  In our own lives we brush up against skepticism with the disquieting thoughts that sometimes appear on the edge of sleep, or when our minds are addled by drugs, mental illness or melancholy.  Skeptical crises can arise in us when we hear some shocking news, face some personal disappointment, or when we recognize some deep failure in ourselves or in the people we love.  We might wonder whether we can really ever know anything, whether this life might be an illusion, a dream, or perhaps an elaborate deception.  Where can I put my trust?  Is there a secure foothold on this cliff, or am I doomed to fall?  This is a widely shared human experience and it has motivated a great deal of inquiry across all the world’s great traditions of philosophical and spiritual traditions.

This personal experience is one of the ways that we are motivated to begin thinking philosophically.  There are other ways.  Aristotle thought that philosophy begins from the feeling of wonder or awe while Plato saw us as being driven to philosophy by love or desire.  Plato’s account sees the philosopher as moving from ordinary desires that are directed towards the beautiful things of ordinary sensual experience to desires directed towards higher things as our understanding progresses.

Buddhists described what they call stream-entry.  Stream entry is the moment when the grip of ordinary life is loosened and we catch a glimpse of something beyond.  One might enter the stream suddenly and without any rational basis.  Perhaps via an insight that comes in a fever, or after an unusual experience or personal crisis, after encountering a work of art, or after hearing a paradoxical or puzzling story like a Zen koan.  Stream-entry can be understood as an initial insight into the nature of the moral and metaphysical order of the universe; what Buddhists call the dharma.

While skepticism shares something in common with the Platonic, Aristotelian, and Buddhist accounts of the beginnings of philosophy, it is more focused on the challenges that life can present.  The kind of painful personal experiences that accompany losses, shocks, despair, and failures can slide quickly into the kind of skeptical mood that leads us to ask basic philosophical questions.  Clearly skepticism is not the only way that we might find our way to philosophy, and yet it seems to be a distinctive and very widely shared concern of those philosophical cultures that developed in the monotheistic traditions of Judaism, Christianity, and Islam.  These philosophical traditions reacted against the more ancient skeptical traditions

Moreover, the personal experience of doubt and the various ways that philosophers have responded to doubt have played an important role in the development of our sense of ourselves as persons who have an inner life and a distinctive kind of personal value and dignity.  From Augustine, to Al-Ghazali, to Descartes, the response to skepticism, the experience of inwardness and the development of subjectivity have all been connected.  While other cultural traditions have their own kind of inwardness, ours has a distinctive character that seems closely connected to the personal response to skeptical crises.

In the philosophical tradition, a radical form of skepticism presents itself as a challenge to the very basis of our knowledge.  The radical skeptic denies that we can ever truly know anything.  On reflection, this radical version of skepticism makes no sense.  How can a skeptic claim to know that we know nothing?  Can there be reasons to believe that we do not truly have reasons to believe? Stated in these terms, skepticism seems obviously false or perhaps just paradoxical.  However, skepticism continues to serve as one of the engines of philosophical inquiry given its connection to our personal experiences of doubt.

For most of us these moments of doubt pass relatively quickly and our usual confidence returns. Nevertheless, these moments are still somehow important.  The times when we realize that all is not right can disrupt the deadening habits of ordinary life, shaking up overconfident and lazy ways of thinking.  These moments can be good for us insofar as they force us to reevaluate our activities and our commitments.  The skeptical mood causes us to ask what we can count on.  What is reliable?  What is really valuable?  What is truly meaningful?  A fully human life must have space for questions of this kind.

The skeptical moments that confront us can be profoundly difficult and we are generally happy to run away from them or to assume an ironic distance from our own condition.  Irony and cynicism are comfortable but unsatisfying postures in the face of these challenges.  While we must seek solace in the ordinary pleasures of life, all of us recognize that a contented existence focused on comfort, fun, and safety is beneath our dignity.  Unlike the cows in the field and the birds in the trees we see beyond the narrow horizon of private amusement, personal security, and advancement.  We know that we are made for more than being sedated or sated. We might turn to self-help gurus for recipes that will allow us to achieve some measure of success and satisfaction.  However, we are also likely to question the whether goals like personal advancement and status, or even peace of mind and contentment are really worth much in the end.  When we ask skeptical questions our minds are directed beyond ordinary, sensible, or practical answers.

Sometimes our capacity to see beyond the practical goals and values of ordinary life can be unbearable and sometimes it is glorious.  The skeptical mood is one of the ways that we can see beyond ourselves to question the truthfulness and value of what we say and do.  Our doubts let us step back from the conformism and unquestioned chatter of the crowd, they also let us maintain a critical distance even from our own desires and preferences. Why do I want what I think I want?  Which of these desires is my own and which is planted in me by the all-pervading commercial culture that we swim in? What is worth wanting?

We cannot do philosophy all the time and inevitably, these moments pass, the demands of ordinary life intervene, and the spirit of skepticism loses its grip on us.  The dog and the children need to be fed, bills need to be paid, work needs to be done.  The eighteenth century Scottish philosopher David Hume, described the difficulty of overcoming his skeptical worries by reason alone but he gratefully acknowledged the fact that ordinary life tends to distract us from difficult questions. In his A Treatise of Human Nature he writes

“Reason is incapable of dispelling these clouds, nature herself suffices to that purpose, and cures me of this philosophical melancholy and delirium, either by relaxing this bent of mind, or by some avocation, and lively impression of my senses, which obliterate all these chimeras. I dine, I play a game of backgammon, I converse, and am merry with my friends; and when after three or four hours’ amusement, I would return to these speculations, they appear so cold, and strained, and ridiculous, that I cannot find in my heart to enter into them any farther.” Book 1, Section 7

Hume saw radical skepticism as a temporary affliction that he could not eliminate by reason alone.  Today, there are few contemporary philosophers who would call themselves skeptics in the strong sense of thinking that we simply cannot know anything.  After all, to confidently claim to know that we cannot know is patently self-contradictory.  In an important sense then, the radical skeptic; he whose doubt extends to everything and who genuinely holds out no hope of knowing anything, is a fictional character.  Practical demands means that such a person can only exist as a figment of our philosophical imagination.  John Locke wrote of the skeptic that he

“would be sure of nothing in this world, but of perishing quickly. The wholesomeness of his meat or drink would not give him reason to venture on it: and I would fain know what it is he could do upon such grounds as are capable of no doubt, no objection.”

In very practical terms there is no realistic way for embodied creatures like us to maintain a disengaged skeptical attitude towards the world for very long without dying of thirst.  Locke and Hume mention food and indeed, the problem with the philosophical skeptic is that in order to maintain an embodied existence it is necessary to act in ways that are informed by basic beliefs about dinner, water fountains, the speed of moving buses, and the location of cliffs and so on.

The radical skeptic could easily defend himself against this kind of concern:  Even if I have the misfortune of not actually existing in the flesh, here at my desk, my location, or lack thereof is a different matter from whether what I say is right or wrong.  What I say, or would have said, can still be right, says the skeptic, even if I don’t happen to exist.

Perhaps nature is secretive, refusing to reveal itself to our senses or our scientific scrutiny. Even if nature does reveal itself, perhaps I am unable to grasp the meaning of the message. If the truth of my claims about the world depends on the ‘underlying reality’ or some other aspect of nature that transcends immediate experience then the truth of my knowledge claim is always by definition going to outstrip my power to certify the truth of my claim to know.

A familiar cast of characters and scenarios relies on some version of this problem. Neo chooses the red pill and escapes the illusory world of the Matrix pumped into his brain by perverted machines, he leaves to David Hume the blue pills and the backgammon and picks instead a life of truth over comforting illusions.  Perhaps we too are living in an illusion.  How could I possibly know that I am not dreaming all of this?  It seems real, but that seeming tells me nothing beyond itself.  It just seems real, but it might not be.

Modern skepticism, the kind we find illustrated by movies like The Matrix or Inception is not the only, tradition of skepticism in the history of philosophy.  For the ancient skeptics of Greece and Rome, skepticism was a way of life.  Locke’s threat of dying by starvation or thirst was not a concern for them since they rejected the idea that believing nothing meant being unable to act. On the contrary, for the ancient skeptics, skepticism was itself a kind of action.  Skepsis, is a greek word meaning inquiry or investigation.  For the ancient skeptics we should reconcile ourselves to ongoing inquiry and should never settle into thinking that anything was true.  Our minds will never settle on the final answer to the most important questions and we should be content to live in a state of suspended judgment.  By rejecting the desire to know the skeptics were fighting something that Aristotle had thought to be essential to human nature.  All human beings, by nature desire to know he writes.  The skeptics might have agreed with him but thought that this desire to know will always be frustrated.  For Pyrrho, rather than having a frustrated desire we should try to eliminate the desire itself.  Overcoming human weaknesses like the desire to know wasn’t always possible even for Pyrrho himself, Diogenes Laertius describes how Pyrrho had been frightened by a dog that attacked him.  Pyrrho confesses that he had exhibited a human weakness and that he would strive to overcome it.

For philosophers like Sextus Empiricus and Pyrrho being a skeptic meant ignoring or suppressing one’s desire to understand the world.  The skeptical philosopher Pyrrho argued that since our desire to know will never be satisfied, we can reach a state of equanimity or happiness, by ridding ourselves of it to the best of our ability.  Rather than striving to know, we should strive to suspend judgment. Rather than attempting to form theories we should abandon all opinions.  It’s not clear how we would abandon all our opinions in practice as Locke would later argue, but for the ancient skeptics the point was that we cannot legitimately assert that any of our beliefs are true.  To assert that some statement about the world is true, Sextus Empiricus argues, is to assert that I have some basis or standard for deciding that the statement is true.  But how are we to judge the reliability of this standard or criterion?  By some other standard presumably.  “If this has been approved” writes Sextus, “that which approves it, in turn has been approved or has not been approved, and so on ad infinitum.” (135)

Even if we were convinced by Sextus’ argument, and we shouldn’t be, the idea that we would find a state of contentment by abandoning our desire to know, struck many other ancient thinkers as implausible.  Believing nothing seems like an unlikely path to happiness.  St. Augustine challenged the skeptical approach to truth by pointing out that we actually know quite a bit without ever needing to trust our senses or rely on authorities.  His argument relies on the fact that when I connect two statements with the word “or” my new statement is true whenever one or both of the two staments are true.  For example if I say that “There are tornadoes on the moon or there are tornadoes in Missourri”  I am saying something true.  Given this property of disjunctions; sentences that are joined together by “or”, it is possible to show that we know an awful lot of true things without needing any standard or criterion of truth in the sense Sextus required.  So, for example we can know that the universe is either finite or infinite, that there are one or more than one things in the universe, etc.

Augustine helped to defeat ancient skepticism by showing how the logic of our knowledge allows us to know some things with certainty.  Even if we doubt the senses and question the reliability of authorities, we can find certainty within, by reflecting on the very nature of our cognitive capacities.  Augustine’s inward turn was a critical moment in human history.  Recall our earlier skeptical worry, when we asked where can I put my trust?  Is there a secure foothold on this cliff, or am I doomed to fall.  For Augustine, by turning inward we find firm footing for our knowledge.

As we have seen, you are unlikely to meet someone who genuinely believes that he knows nothing, or that everything is open to doubt. In practice we prove that we are not skeptics when we act, when we eat our sandwiches, respond to our email, and care for our children.  But as Augustine, al-Ghazali, and later Rene Descartes show, the logic of the skeptic’s argument is self-undermining.  Perhaps more importantly, though, the skeptical moment is what gives Augustine, al-Ghazali, and Descartes access to this deeply subjective inward dimension of experience.  Much of what it means to be a modern individual is due to the journey inwards that these philosophers helped to initiate.  We can thank skepticism in its ancient and modern forms for that.