On Radical Skepticism
Skepticism, in its most useful sense, begins with doubt and demands reasons for believing. It is not an attitude of sulky refusal, but a method of inquiry. To be skeptical is to say, “before I claim to know, I should be able to say what would count as evidence - what criteria I am using, and how I would distinguish knowledge from mere opinion.” This modest starting point differentiates skepticism from incredulity. Incredulity is a mood - skepticism is a discipline.
Methodological and Limited Skepticism
The first, and philosophically respectable, form of skepticism is methodological. Hypothetically speaking, it appears when someone points to an object and asks, “how do you know it's there?” The person asking would not seriously fear that the chair will vanish. The exercise is to force articulation of the criteria that are normally taken for granted. One might answer that he or she can see and touch the object. Another might add that others can verify the same sensory observations. From there, the inquiry can expand. The evidence for the existence of an object is not the same kind of evidence we give for a mathematical truth, and that in turn differs from the “evidence” people try to offer for moral or religious claims. Methodological skepticism maps those differences.
Limited skepticism pushes this further and then stops. It says, "in some domains we can have knowledge; in others we must content ourselves with opinion." Modern scientific optimism once assumed that empirical science yields knowledge while ethics and religion yield only subjective belief. Medieval thought often reversed this ranking, treating sensory knowledge as fragile and revelation as secure. The details shift, but the structure remains: there is a contrast between areas where our standards of justification can be met and areas where they cannot. Limited skepticism is not a blanket denial of knowledge. It is a sorting exercise that asks where strong claims are appropriate and where humility is required.
Radical Skepticism as Emergency Exit
Radical skepticism is something else entirely. It insists that there is no knowledge, no truth, or that nothing exists beyond one’s own mind. It often appears at the end of an argument rather than the beginning. A person starts by asserting that they know what virtue, justice, or God is. When challenged and refuted several times, they may suddenly declare that nobody knows anything. Philosophers from Aristotle onward have pointed out that such positions saw off the branch on which they rest. Aristotle’s discussion in Metaphysics (Book IV) is exemplary here, since he treats the denial of truth as a position that collapses as soon as it is expressed - viz., if someone says, “there is no truth,” the obvious question is “Is that sentence true?” If it is, then at least one truth exists. If it is not, the position refutes itself. The same holds if they claim to have reasons or evidence for the denial of truth. Reasons and evidence only make sense in a world where there is some distinction between better or worse - true and false - accounts. To insist that nothing is true while presenting arguments is to demand that those arguments be taken seriously in a way one’s own doctrine forbids.
Solipsism and the Subjective Turn
A more subtle version of radical skepticism claims that all truth is subjective. The world, on this view, has no determinate structure apart from what we think or feel about it. There are no objective facts, only perspectives. Common sense and scientific practice sit uneasily with this posture. If all truth were subjective, one’s belief about having money in the bank would make it so. One’s belief in immortality would render one immortal. That is not how reality behaves. The distinction between objective and subjective turns on precisely this difference. Objective facts are those that hold whether anyone believes them or not. Subjective states, such as pains or dreams, exist only insofar as they are experienced. The concepts are paired. If there were no sense in which things are independent of our minds, the concept of subjectivity would have no contrast.
Solipsism draws the subjective move to its extreme, claiming that only one’s own consciousness can be known to exist. The position is logically unstable and psychologically suspect. Those who announce it still talk to others, demand their rights, and protest when ignored. In other words, the behavior contradicts the professed belief. Language itself presupposes a shared world and shared forms of life. To understand a sentence such as "Only my mind exists" requires a background grasp of what mind and existence consist of, and that background is learned through experience in a common, natural, and social world.
Loss of Mythology and the Temptation to Doubt Everything
Why, then, does radical skepticism attract people at certain historical moments? One answer lies in what can be called "loss of mythology." When the background beliefs that once organized a life collapse—through war, cultural upheaval, personal crisis—two symmetrical errors tempt the mind. The first is naïve belief - viz., accepting inherited narratives without scrutiny. The second is equally uncritical doubt - refusing to believe anything, regardless of evidence. Both bypass the patient work of asking how to form beliefs that can withstand challenge. In such moments, radical skepticism can feel like honesty. If the old certainties have failed, perhaps there were never any truths at all. Yet this response keeps one at the bottom of the cave rather than moving toward understanding. A more mature skepticism acknowledges that earlier beliefs were held too cheaply, then turns toward the more arduous task of articulating standards, revising assumptions, and differentiating what can be known from what must remain open.
Skepticism as Discipline, Not Refuge
The deepest lesson is not that skepticism should be rejected. Quite the contrary. Methodological and limited skepticism are indispensable tools. They prompt clarity about what is being claimed when someone says, “I know,” and they draw needed lines between strong knowledge claims and more tentative commitments. Radical skepticism, by contrast, tends to be a refuge from responsibility. It undermines the very practices—argument, inquiry, and shared language—that make criticism and revision possible. To “start with doubt” in a fruitful way is to ask, in each context, what standards of justification are appropriate and how they can be met. It is to treat consciousness as a window with imperfections rather than a wall. In this sense, skepticism is not a denial of the world. It is a disciplined way of remaining open to answers. Furthermore, it marks a commitment to ongoing justification - free from naïve certainty or performative doubt, which is precisely what distinguishes serious epistemology from rhetorical evasion.
Questions for Reflection
- When you claim to “know” something in your own life, what criteria are you actually using, and how do those criteria differ across domains such as everyday perception, scientific claims, moral judgments, or religious beliefs?
- Can you identify a time when you (or someone you know) used a form of radical skepticism as an “escape hatch” in an argument? What might a more disciplined, methodological skepticism have looked like in that situation instead?
- How does the distinction between objective and subjective truth appear in your daily reasoning? Are there beliefs you treat as if they were purely subjective that in practice guide your actions as though they were objective, or vice versa?
- Have you experienced a “loss of mythology” moment, in which background beliefs or narratives collapsed? In this context, what would it mean to practice mature skepticism - neither clinging to old certainties nor sliding into performative doubt?
Suggested Reading
René Descartes, Meditations on First Philosophy.
Aristotle, Metaphysics. Book IV.
Michael Williams, Problems of Knowledge:
A Critical Introduction to Epistemology (2001).
Barry Stroud, The Significance of
Philosophical Scepticism (1984).
Ludwig Wittgenstein, On Certainty. 1969.