# Wolfgang Schwarz

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I stumbled across a few interesting free books in the last few days.

1. Tony Roy has a 1051 page introduction to logic on his homepage, which slowly and evenly proceeds from formalising ordinary-language arguments all the way to proving Gödel's second incompleteness theorem. All entirely mainstream and classical, but it looks nicely presented, with lots of exercises.

## Ifs and cans

Is 'can' information-sensitive in an interesting way, like 'ought'?

An example of uninteresting information-sensitivity is (1):

(1) If you can lift this backpack, then you can also lift that bag.

Informally speaking, the if-clause takes wide scope in (1). The truth-value of the consequent 'you can lift that bag' varies from world to world, and the if-clause directs us to evaluate the statement at worlds where the antecedent is true.

## Should you rescue the miners?

Many accounts of deontic modals that have been developed in response to the miners puzzle have a flaw that I think hasn't been pointed out yet: they falsely predict that you ought to rescue all the miners.

## Iterated prisoner dilemmas

There's something odd about how people usually discuss iterated prisoner dilemmas (and other such games).

Let's say you and I each have two options: "cooperate" and "defect". If we both cooperate, we get $10 each; if we both defect, we get$5 each; if only one of us cooperates, the cooperator gets $0 and the defector$15.

## Time consistency and stationarity

Suppose you prefer $105 today to$100 tomorrow. You also prefer $105 in 11 days to$100 in 10 days. During the next 10 days, your basic preferences don't change, so that at the end of that period (on day 10), you still prefer $105 now (on day 10) to$100 the next day. Your future self then disagrees with your earlier self about whether it's better to get $105 on day 10 or$100 on day 11.

## Decision theory notes

In the last four months I wrote a draft of a possible textbook on decision theory. Here it is.

I've used these notes as basis for my honours/MSc course "Belief, Desire, and Rational Choice". They're tailored to my usage, but they might be useful to others as well.

## Three kinds of preference

The decision-theoretic concept of preference is linked to the concepts of subjective probability and utility by the expected utility principle:

(EUP) A rational agent prefers X to Y iff the expected utility of X exceeds the expected utility of Y.

Economists usually take preference to be the more basic concept and interpret the EUP as an implicit definition of the agent's utilities (and sometimes also her probabilities).

## Justification at a distance

According to a popular picture, some beliefs are justified by "seemings": under certain conditions, if it seems to you that P, then you are justified to believe that P, without the assistance of other beliefs. So seemings provide a kind of foundation for belief, albeit a fallible kind of foundation.

## Lewis on possible worlds and the grounds of modality

Friends of primitive powers and dispositions often contrast their view with an alternative view, usually attributed to Lewis, on which modal facts about powers, dispositions, laws, counterfactuals etc. are grounded in facts about other possible worlds. But Lewis never held that alternative view – nor did anyone else, as far as I know. The allegedly mainstream alternative is entirely made of straw. The real alternative that should be addressed is the reductionist view that powers and dispositions are reducible to ultimately non-modal elements of the actual world.

## Dicing with death

In his "Dicing with Death" (2014), Arif Ahmed presents the following scenario as a counterexample to causal decision theory (CDT):

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