In the context, part II of Ulysses and the Sirens by Jon Elster had just been summarized.
Elaborate on the Pascal vs Descartes contrast.
Here’s a clear, expanded contrast between Pascal and Descartes as they appear in Imperfect Rationality—not as historical caricatures but as two different models of how agents cope with their own limits.
1. What the contrast is really about
The chapter uses Pascal and Descartes as ideal types representing two radically different approaches to imperfect rationality:
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Pascal = self-transformation through behavior.
“Act first, and your mind will follow.” -
Descartes = stability through rules.
“Choose a principle, then stick to it even if your moment-by-moment reasoning wavers.”
It’s a contrast between engineering your future preferences (Pascal) and engineering your future choices (Descartes).
2. Pascal: shaping beliefs and preferences from the outside in
The method (Pascal’s wager as model)
Pascal says: belief can be cultivated indirectly.
If you cannot will yourself to believe, then:
- Attend Mass
- Kneel
- Participate in ritual
- Live as if you already believe
And in time—through habit, imitation, and emotional conditioning—you will.
Core assumptions
-
We are malleable. Preferences, commitments, and even beliefs can be molded by repeated action.
-
We cannot directly command belief. We must sneak up on ourselves.
-
Self-deception is partly functional. To succeed, you must eventually forget you engineered the change.
- This is the Williams paradox: self-manipulation works only if the self forgets what it is doing.
Philosophical style
- Pragmatic: don’t ask whether you believe—start behaving as though you do.
- Emphasizes habit, imitation, social reinforcement.
- Centers on preference formation, not just choice.
Modern echoes
- Cognitive-behavioral therapy
- Habit-first moral development (Aristotle)
- “Fake it till you make it”
- Nudges and identity-shaping behavior
Danger points
- Slippery toward manipulation, seduction, indoctrination
- Blurs the line between autonomy and training
3. Descartes: rules to navigate moments of epistemic fog
The model (the “methodic resolution” in the forest)
Descartes gives the parable:
If you are lost in a forest and have no idea which way leads out, pick a direction and walk straight. Re-evaluating at each fork will leave you circling.
This is a template for decisions when:
- You lack information,
- You are prone to waver,
- You expect local optimization to harm you.
Core assumptions
-
Human reason is unstable moment-to-moment.
The best way to approximate rationality is to bind yourself to a principle chosen when you were calm and reflective. -
Rules beat re-optimization.
“Best for now” thinking leads to dithering, inconsistency, and suboptimal wandering. -
Consistency itself produces value.
Stability reveals patterns (to yourself and others), encourages coordination, and prevents being swayed by noise.
Philosophical style
- Constitutional, procedural, quasi-Kantian
- Trusts second-order rationality (choosing rules) more than first-order rationality (making each decision afresh)
Modern echoes
- Constitutional economics (rules vs. discretion)
- Central bank independence
- Bright-line moral rules
- Resolutions like “I do not gamble,” not “I’ll see each time if it’s wise”
Danger points
- Rules can be stupid in new contexts
- Can harden into rigidity
- May require periodic, but rare, exceptions—raising the question of how to recognize them without undermining the rule
4. Why the contrast matters for imperfect rationality
Pascal: change the agent
—reshape preferences so the right actions will become natural.
Mechanism: habit, emotion, social ritual, environment.
Descartes: constrain the agent
—set rules so the actual future self will act correctly regardless of temptations.
Mechanism: precommitment, bright lines, algorithmic discipline.
Both aim to improve long-term rationality, but through different causal pathways.
5. Where each strategy wins
Pascalian strategies succeed when:
- The goal is identity change
- Motivation is fragile
- Habits matter more than discrete choices
- You want eventual internalization (“make this natural to me”)
Cartesian strategies succeed when:
- The environment is unstable
- Temptation is sudden and sharp
- You need predictability
- Coordination with others depends on consistent, rule-like behavior
6. Why the chapter treats them as complementary, not competitors
Pascal = soft self-binding (transform who you are).
Descartes = hard self-binding (restrict what you can do).
Real agents use both:
- A dieter may adopt Pascalian habits (small plates, healthy routines)
- …and Cartesian rules (“no eating after 8 p.m.”)
The deep insight is that perfect rationality doesn’t exist in humans,
so agents must build external scaffolds (Descartes)
and internal workarounds (Pascal).
If you want, I can also:
- Compare how each handles self-deception,
- Show how both map onto game-theoretic self-control models (Ainslie/Strotz/Pollak),
- Relate them to constitutional politics and collective action,
- Or give concrete real-world examples of Pascalian vs. Cartesian strategies.
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