Belief in Psyontology

Jonathan Weisberg

University of Toronto


Two Notions

  1. Full belief: S believes that P.
    • Sonja believes Reykjavik is the capital of Iceland.
  2. Partial belief: S is x confident that P.
    • Julia is 95% sure spiders have eight legs.

Two Questions

  1. Metaphysics: how are full and partial beliefs related?
    • Do full beliefs reduce to partial beliefs, e.g. are they just strong partial beliefs?
  2. Epistemology: when should one state affect the other?
    • Is there a threshold above which partial belief warrants full belief?
    • Should your partial beliefs be based on your full beliefs?

Some Standard Views

  1. Dualism: full and partial beliefs are both real, and they are fairly metaphysically independent.
    • Serious epistemology must address both.
  2. Eliminativism: no such thing as full belief; corrupt legacy notion.
    • Replace it with partial belief.
  3. Reductionism: full beliefs are real, but mere coarsenings of partial beliefs.
    • Dismissive Reductionism: these coarsenings have little/no epistemological significance.
    • Respectful Reductionism: these coarsenings are epistemologically signficant.

To Be Shown

  1. Dualism ✔
  2. Eliminativism ✘
  3. Reductionism ✘


Pros of Dualism

  1. Respects folk discourse
  2. Respects phenomenology:
    • Acceptance/settling
    • Premising

Cons of Dualism

  1. Parsimony, or a lack thereof:
    • Descriptive: ontological baggage + more convoluted psychology
    • Normative: more convoluted epistemology
  2. Causal overdetermination
    • Beliefs are supposed to cause/explain inferences, actions, and assertions.
    • Which kind of belief does this—full or partial?
  3. Normative conflict: The Dualist Dilemma

The Dualist Dilemma

From Epiphenomenonalism…

“Levi urges that the notions of belief, disbelief, and suspension of judgment […] are no less but no more in need of clarification than the notions of declaring war, taking a walk, writing a book, and cooking an omelet […] I doubt this. True enough, the notions of belief, disbelief, and suspension of judgment are as familiar as those of declaring war, taking a walk and the rest; but so are the notions of luck, divination, and lunacy.” (Jeffrey 1968)

…to Infallibilism


The Temptations of Eliminativism

  1. Ontological parsimony
  2. Epistemological parsimony:
    • Bayesianism: pre-assembled, batteries & decision theory included.
  3. No causal overdetermination problem
  4. No normative conflict, hence no paradoxes of acceptance:
    • Preface, Harman-Vogel, bootstrapping, etc… all gone.
Summary: all the advantages of abandonment over honest toil!

Cons of Eliminativism

Dracula Meets Wolfman

“[…] nor am I disturbed by the fact that our ordinary notion of belief is only vestigially present in the notion of degree of belief. I am inclined to think Ramsey sucked the marrow out of the ordinary notion, and used it to nourish a more adequate view.” (Jeffrey 1970)

Roll 2:12!

“In the simplest cases, the number of possible acts that the agent believes are available to him is finite, as is the number of possible circumstances that he regards as relevant to the outcomes of the acts.” (Jeffrey 1965)

More Seriously

  1. Massive error theories should be a last resort.
  2. Eliminativism clashes with empirical research, as we’ll see.


“I have high credence I can fly”

Basically: S believes that P just in case S has high credence in P.

The Charms of Reductionism

  1. Ontological parsimony
  2. Epistemological parsimony:
    • Bayesianism for partial beliefs, Lockeanism for full beliefs
  3. No causal overdetermination
  4. No normative conflict—always defer to your partial beliefs.
    • E.g.: solve the preface by replacing deductive consistency with coherence of the underlying credences.

Dismissive Reductionism: Christensen

“It is clear that our everyday binary way of talking about beliefs has immense practical advantages over a system which insisted on some more fine-grained reporting of degrees of confidence […] What is somewhat doubtful, though, is that this project will reveal to us a species of belief that will prove important from the point of view of epistemic rationality.” (Christensen 2004)

A Worry…

“The debate on climate change ought not to be whether or not it exists. It is what we should do about it.” –John Oliver

The Decision-Theoretic Gambit

Respectful Reductionism: Sturgeon

My Beef with Sturgeon

Respectful Reductionism: Foley

My Son, My Son… What Have Ye Done?

Moral: A Functional Distinction



The Two Hanneses

Good vs. Evil

Good Hannes

“If one understands our question […] from this ontological point of view, then it is inevitable that in order to answer it successfully one will need to carry out some empirical investigations into belief along the lines of: what are the agent’s belief-generating systems like?” (Leitgeb 2013)

The Question to Ask Then

Empirical Evidence

Three Literatures

  1. Memory
  2. Judgment & Decision-Making
  3. Cognitive Closure

Part 1: Memory

Confidence & Memory


(Nelson and Narens 1990)

A Stroll Down Metamemory Lane

(Nelson and Narens 1990)

Do Humans Store Credences?

A Naive Argument

  1. Human memory stores factual information, sans confidence levels.
  2. Confidence levels are constructed at the time of recall, based on metacognitive cues like fluency & quantity.
  3. So full belief is ontologically prior to partial belief!

A More Careful Look

Even So, Some Traction

  1. Belies an apparent, extreme disadvantage w.r.t. parsimony
    • Pitting Carnap’s Robot against the Leviathan makes the Leviathan look unwieldy, redundant, unnecessarily complicated.
    • But maintaining full beliefs doesn’t actually require extra/redundant storage and updating.
      • Full & partial belief share storage.
      • “Updating” actually happens on the fly (at least partly).

A Bit More…

  1. Also suggests a picture on which neither form of belief is prior to the other:
    • We’re disposed to judge recalled information true by default.
    • Defeating information or disfluency can trigger hesitation, doubt, and further processing.
    • 1 information store, 2 kinds of processes drawing on it.


. . .


Reply, part II


Part 2: Judgment & Decision-Making

Substantive vs. Procedural

“Economics is a theory of human rationality that must be as concerned with procedural rationality—the ways in which decisions are made—as with substantive rationality—the content of those decisions.” (Simon 1981)

Monolithic vs. Fractured

“…decision researchers increasingly believe that […] preferences are not generated by some invariant algorithm such as Bayesian updating or expected utility calculations, but instead are generated by the contingent use of a variety of different decision heuristics or simplification mechanisms.” (Payne and Bettman 2004)

Crash Course in Decision Strategy

The JDM Literature


the Garage Days


Becoming Some Kind of Monster

Varieties of Judgment & Decision

’70s: Heuristics & Biases

’80s & ’90s: The Adaptive Toolbox

Tools in the Box: WADD

WADD: Two Notes

  1. WADD is formally equivalent to EU-max: both are linear weightings.
    • The interpretation is different though:
      • outcomes are replaced by features.
      • utilities are replaced by degrees of feature-possession.
      • probabilities are replaced by degrees of feature-importance.
  2. WADD is fully compensatory:
    • Evaluates all the information available.
    • Recommendations based on more important features can be overturned by considering less important features.

An Aside: Alternatives vs. Attributes

Tools in the Box: LEX

Tools in the Box: EBA

Tools in the Box: TALLY-n

Tools in the Box: Combo Packs

’00s: The Adjustable Spanner, EAM

EAM: An Example

E.A.M. ⇒ U.N.I.T.Y.




  1. Well look who’s being unparsimonious again!
  2. There’s good empirical reason to think assumptions aren’t weighted.
    • EIPs: measuring the effort and time a procedure requires.
    • Turns out PRODUCT is very expensive.
      • By far the most time-consuming
      • 2nd for self-reported effort
    • Related: (Shah and Oppenheimer 2008; Stanovich 2009)

The Unbearable Weightiness of Bayesianism

Bettman, Johnson, & Payne (1990)

Part 3: Cognitive Closure

I Feel the Need…

“Where high degrees of confidence are compatible with a continuing feeling of uncertainty, outright belief yields the subjective sense of a solid result. Psychologists who have studied these phenomenal qualities have characterized them in a way that would support the notion that […] we switch from an anxious phase of searching for evidence and weighing it to a satisfied or relieved phase of possessing a determinate representation…” (Nagel 2010)

…the Need for Closure

“Kruglanski introduces the term ‘closure’ as a name for arrival at a settled belief: in his words, closure is ’the juncture at which a belief crystallizes and turns from hesitant conjecture to a subjectively firm”fact" […] Achieving closure or judgemental commitment on a question puts an end to the experience of ambiguity and delivers the sense of having a firm answer." (Nagel 2008)

The Nature of NFC

Consequences: Seizing & Freezing

  1. Urgency: motivation to close can yield “seizing”.
    • Jumping on “any notion that promises closure”
    • Leaping to conclusions with skimpy evidence
  2. Permanence: aversion to surrendering closure can yield “freezing”.
    • Reluctance to reopen a question
  3. These aims can pull against one another though:
    • We “abhor the specter of having to part with closure.”
    • So we may prefer to wait for a stable, lasting answer. See (Kruglanski and Webster 1996; Kruglanski 2004) for details.

The High NFC Personality

The High NFC Personality

High NFC & Biases

More Concrete Predictions I

Concrete Predictions II

Concrete Predictions III

And On and On (and On)



Just a Friendly Ammendment?

Not So Friendly After All

“I do not usually consult many different options before forming my own view.”

“When thinking about a problem, I consider as many different opinions on the issue as possible.”

“Even after I’ve made up my mind about something, I am always eager to consider a different opinion.”

License to Ignore


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