Think - Simon Blackburn
Chapter One — “Knowledge”
Overview of the Main Idea and Themes
Blackburn introduces the classic epistemological problem: how can we know that the world is as we take it to be, rather than a dream, illusion, or deception? Using Descartes’s Meditations as the core case study, he traces the arc from radical doubt (dreams, the Evil Demon) to the “Cogito,” then evaluates Descartes’s attempt to rebuild knowledge via “clear and distinct ideas,” God’s existence, and the guarantee against deception. Blackburn then surveys major responses—rational foundationalism, natural foundationalism (Hume), coherentism, and varying scopes of skepticism—closing with the enduring moral: skepticism persistently challenges any confident harmony between appearance and reality.
Key Arguments, Facts, and Developments (in sequence)
1) Opening puzzle: Losing the world
- The chapter begins with a childhood inquietude: perhaps everything is a dream or virtual reality. Why are we right to dismiss this? The question frames the appearance/reality divide at the heart of epistemology.
2) Why start with Descartes
- Though skepticism is ancient (Vedas; Montaigne’s “Que sais-je?”), Descartes is “one of us” because he confronts the new mechanical science (Copernicus, Galileo) and tries to make room for God, freedom, and the human spirit within it. His Meditations (1641) aim to demonstrate God’s existence and the soul’s distinctness from body, while “rescuing” modern science from charges of atheism and materialism by reflecting on knowledge’s foundations.
3) The Method of Doubt (Meditation I)
- Descartes resolves to demolish prior opinions and start from foundations because the senses sometimes deceive. Dreams show experiences can feel veridical yet be false. He intensifies doubt with the Evil Demon hypothesis: a powerful deceiver could make all external things—sky, earth, colors, sounds—mere delusions. For the project, he must withhold assent from anything possibly false.
4) Cogito, ergo sum (Meditation II)
- In the sea of doubt, one certainty remains: “I am, I exist,” whenever I think it. Even if deceived, the act of being deceived confirms a thinker. This is the Cogito. The self, thus secured, cannot be known by imagination (which requires bodies) but as a thinking thing.
- Wax example: A ball of wax changes all sensory qualities by the fire yet is judged the same thing. Identity across change is apprehended by the intellect, not the senses or imagination. Result: even bodily knowledge is by understanding; and the mind is known more certainly than anything else.
5) Diagnosing Descartes’s opening moves
- Blackburn reconstructs the doubt: “Senses sometimes deceive” does not validly imply “they always might be deceiving us en bloc.” A better (but weaker) argument is: we can’t always tell, in the moment, which experiences deceive—though over time we often can (self-corrective senses). Dreams raise the bar, but tests from inside dreams (pinching, experiments) can themselves be dreamt, keeping the skeptical challenge alive. The Evil Demon abstracts from specific illusions to a global scenario—scale and coherence of experience cannot easily refute it, since the Demon could simulate both.
6) The elusive “I”
- A tempting but fallacious step: “I can’t doubt I exist; I can doubt bodies; therefore I am not a body.” This echoes the “masked man” fallacy (knowing vs. being). Blackburn suggests Descartes’s real point is epistemic priority: knowledge of self does not depend on knowledge of bodies, not a full-blown substance dualism proof. Lichtenberg’s challenge—say “it thinks,” as we say “it thunders”—questions whether the Cogito secures a substantive self or merely the occurrence of thought. Blackburn notes the tension and brackets it for later chapters.
7) Clear and distinct ideas; rationalism and the a priori
- Why is the Cogito certain? Descartes appeals to clarity and distinctness as a mark of truth, modeled on mathematical insight (e.g., a geometric proof that suddenly becomes self-evident). This seeds rationalism: some truths are knowable a priori, by reason alone.
8) The “Trademark” argument for God (and why it falters)
- Descartes argues: I have an idea of a perfect being; effects require causes at least as perfect as themselves; thus only God could cause this idea; therefore God exists and, being perfect, is no deceiver. Blackburn’s critiques:
- The “every idea must have an adequate cause” premise is not Demon-proof and is questionable in itself.
- Causal “resemblance” or “passing on” of properties is historically assumed but false; many causes don’t resemble effects (e.g., magnetism/electricity).
- Having a defined idea (e.g., “perfect punctuality”) doesn’t entail a perfect exemplar exists to cause it; we can specify conditions without acquaintance.
- Even Descartes’s own analogy (we can “touch” a mountain with thought without “embracing” it) undercuts full comprehension of divine perfection needed for the argument.
Overall, the proof is not secure enough to silence the Demon.9) The Cartesian Circle
- After “proving” God, Descartes uses God’s non-deceptiveness to certify clear and distinct ideas. But to reach God he already relied on clear and distinct perception—seeming circularity (Arnauld’s objection). Attempts to escape: perhaps God secures memory of proofs, while present clear vision needs no guarantee; or perhaps one can have certainty in a particular clear insight without a general rule. Blackburn notes the “whiff of double standards”: the radical skeptical worry is quietly sidelined when convenient.
10) Hume’s challenge and the fate of foundations
- Hume argues that universal doubt about our faculties is either impossible to sustain or incurable by reason; no “original principle” can, without circularity, certify the very faculties used to infer it. Descartes’s project, if taken literally, cannot succeed.
11) Four broad options in epistemology
- Rational foundationalism (Descartes): indubitable, reason-certified foundations—problematic.
- Natural foundationalism (Hume): we trust senses and reason as a matter of nature/practice; systems are self-corrective over time; labels “a priori rescue” as unnecessary.
- Coherentism: knowledge is a web—mutual support without any ultimate base (Neurath’s ship). Attractive, but the Demon scenario shows an internally coherent web could still be globally false.
- Skepticism: no knowledge; always a live option haunting the rest.
- Blackburn also notes an evolutionary consolation: our faculties were selected because they track survival-relevant truths; this is not a Demon refutation but a naturalistic explanation of general reliability. Still, Humean doubts about induction will re-emerge later.
12) Local skepticisms and Russell’s “time” puzzle
- Skepticism can target domains (ethics, politics) without denying all knowledge. Russell’s time hypothesis: the world might have sprung into existence moments ago with “traces” (memories, fossils) of great age. Strikingly, thermodynamic reasoning can make this seem probable relative to lower-entropy origins—a neat sting showing how scientific considerations can unsettle “common sense” chronology.
13) The moral
- Knowledge claims imply authority and reliability; skeptical scenarios unseat confidence in our reliability. Because we can’t show such scenarios impossible, and lack non-question-begging probability estimates, skepticism permanently beckons. Our conceptual “engineering” spans a gap between appearance and reality, but the scaffolding’s ultimate security remains contested. This leaves a standing problem of knowledge that will shadow the rest of the book.
Notable Quotes (brief, representative)
- On the Evil Demon: the deceiver could make “the sky, the air, the earth, colours, shapes, sounds and all external things” mere delusions; hence the need to suspend belief to avoid error.
- On the Cogito: “I am, I exist, is necessarily true whenever it is put forward by me or conceived in my mind.”
- On the wax: after all sensible qualities change, “the wax remains,” so bodies are understood “by the intellect alone.”
- Neurath’s ship: “We are like sailors who on the open sea must reconstruct their ship but are never able to start afresh from the bottom.”
- On the moral of skepticism: confidence in harmony between appearings and reality may be “a pure act of faith.”
How the Chapter Connects to the Whole Book
- Sets epistemological baseline: The chapter frames the overarching problem of knowledge and the strategies for addressing it, establishing themes that will recur (mind–body, self, causation, induction, ethics).
- Models Blackburn’s method: sympathetic reconstruction of classic arguments, followed by careful diagnosis of validity, suppressed premises, and alternative readings. Expect this pattern in subsequent chapters.
- Previews later debates: the mind’s nature (raised by the Cogito and the elusive “I”), Hume’s skepticism (revisited on induction/causation), and the tension between rationalist and empiricist ideals.
Concise Takeaway
Blackburn uses Descartes’s Meditations to dramatize the problem of knowledge: radical doubt strips us to the Cogito, yet attempts to rebuild the world through “clear and distinct ideas” and God face serious obstacles (trademark argument, Cartesian circle). Alternatives—natural foundations, coherent webs—each leave room for skepticism. The chapter closes by underscoring that the lure of skepticism persists, setting up the book’s continuing inquiry into whether, where, and how our conceptual “engineering” can secure reliable contact with reality.
Link to original
References
René Descartes (Stanford Encyclopedia of Philosophy)
Kumārila (Stanford Encyclopedia of Philosophy)
Michel de Montaigne (Stanford Encyclopedia of Philosophy)
Georg Christoph Lichtenberg
Continental Rationalism (Stanford Encyclopedia of Philosophy)
Rationalism vs. Empiricism (Stanford Encyclopedia of Philosophy)
Cartesian circle
Hume on Religion (Stanford Encyclopedia of Philosophy)
Constructive Empiricism (Stanford Encyclopedia of Philosophy)
Logical Empiricism (Stanford Encyclopedia of Philosophy)
Ancient and Medieval Empiricism (Stanford Encyclopedia of Philosophy)
Normative Theories of Rational Choice: Expected Utility (Stanford Encyclopedia of Philosophy)
Normative Theories of Rational Choice: Rivals to Expected Utility (Stanford Encyclopedia of Philosophy)
Foundationalist Theories of Epistemic Justification (Stanford Encyclopedia of Philosophy)