Recent content on Jonathan Weisberg
As Joe Biden cleared 270 last week, some people remarked on how different the narrative would’ve been had the votes been counted in a different order: It's staggering to think about how differently PA would be viewed/covered right now if the EDay/mail ballots were being counted in the opposite order. — Dave Wasserman (@Redistrict) November 5, 2020 The idea that order shouldn’t…
This is post 3 of 3 on simulated epistemic networks (code here ): The Zollman Effect How Robust is the Zollman Effect? Mistrust & Polarization The first post introduced a simple model of collective inquiry. Agents experiment with a new treatment and share their data, then update on all data as if it were their own. But what if they mistrust one another? It’s natural to have less than full…
This is the second in a trio of posts on simulated epistemic networks: The Zollman Effect How Robust is the Zollman Effect? Mistrust & Polarization This post summarizes some key ideas from Rosenstock, Bruner, and O’Connor’s paper on the Zollman effect, and reproduces some of their results in Python. As always you can grab the code from GitHub. Last time we met the Zollman effect:…
I’m drafting a new social epistemology section for the SEP entry on formal epistemology . It’ll focus on a series of three papers that study epistemic networks using computer simulations. This post is the first in a series of three explainers, one on each paper. The Zollman Effect How Robust is the Zollman Effect? Mistrust & Polarization In each post I’ll summarize the main ideas…
In an earlier post we met the $\lambda$-continuum, a generalization of Laplace’s Rule of Succession . Here is Laplace’s rule, stated in terms of flips of a coin whose bias is unknown. The Rule of Succession Given $k$ heads out of $n$ flips, the probability the next flip will land heads is $$\frac{k+1}{n+2}.$$ To generalize we introduce an adjustable parameter, $\lambda$. Intuitively…
Which is more fundamental, full belief or partial belief? I argue that neither is, ontologically speaking. A survey of some relevant cognitive psychology supports a dualist ontology instead. Beliefs come in two kinds, categorical and graded, with neither kind more fundamental than the other. In particular, the graded kind is no more fundamental. When we discuss belief in on/off terms, we are not…
Evidence is univocal, not equivocal. Its implications don’t depend on our beliefs or values, the evidence says what it says. But that doesn’t mean there’s no room for rational disagreement between people with the same evidence. Evaluating evidence is a lot like polling an electorate: getting an accurate reading requires a bit of luck, and even the best pollsters are bound to get…
The Rule of Succession gives a simple formula for “enumerative induction”: reasoning from observed instances to unobserved ones. If you’ve observed 8 ravens and they’ve all been black, how certain should you be the next raven you see will also be black? According to the Rule of Succession, 90%. In general, the probability is $(k+1)/(n+2)$ that the next observation will be…
There are four ways things can turn out with two flips of a coin: $$ HH, \quad HT, \quad TH, \quad TT.$$ If we know nothing about the coin’s tendencies, we might assign equal probability to each of these four possible outcomes: $$ Pr(HH) = Pr(HT) = Pr(TH) = Pr(TT) = 1/ 4. $$ But from another point of view, there are primarily three possibilities. If we ignore order, the possible outcomes are…
The classic “Lockean” thesis about full and partial belief says full belief is rational iff strong partial belief is rational. Hannes Leitgeb’s “Humean” thesis proposes a subtler connection. $ \newcommand\p{Pr} \newcommand{\B}{\mathbf{B}} \newcommand{\given}{\mid} $ The Humean Thesis For a rational agent whose full beliefs are given by the set $\mathbf{B}$, and whose…
If you look at the little network diagram below, you’ll probably agree that $P$ is the most “central” node in some intuitive sense. This post is about using a belief’s centrality in the web of belief to give a coherentist account of its justification. The more central a belief is, the more justified it is. But how do we quantify “centrality”? The rough idea: the…
Today The Open Handbook of Formal Epistemology is available for download . It’s an open access book, the first published by PhilPapers itself. (The editors are Richard Pettigrew and me.) The book features 11 outstanding entries by 11 wonderful philosophers. “Precise Credences”, by Michael G. Titelbaum “Decision Theory”, by Johanna Thoma “Imprecise…
In Risk & Rationality , Buchak (2013) advertises REU theory as able to recover the modal preferences in the Allais paradox. In our (2017) however, we pointed out that REU theory only applies in the “grand world” setting, where it actually struggles with the modal Allais preferences. Buchak (2017) offers two replies. Here we enumerate a variety of technical and philosophical problems…
How does prestige correlate with placement in academic philosophy? There’s good stuff on this already, like this post by Carolyn Dicey Jennings, Pablo Contreras Kallens, and Justin Vlasits. 1 This post uses the same data sources, but emphasizes different things (visualization, North American PhDs, and primarily tenure-track jobs). TT Placement in North America Let’s start with a simple…
Here’s a striking result that caught me off guard the other day. It came up in a facebook thread, and judging by the discussion there it caught a few other people in this neighbourhood off guard too. The short version: chances are “self-expecting” pretty much if and only if they’re “self-certain”. Less cryptically: the chance of a proposition equals its expected…