### Ideas from 'Necessary Beings' by Bob Hale [2013], by Theme Structure

#### [found in 'Necessary Beings' by Hale,Bob [OUP 2013,978-0-19-874803-8]].

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###### 1. Philosophy / E. Nature of Metaphysics / 1. Nature of Metaphysics
 19275 You cannot understand what exists without understanding possibility and necessity
###### 2. Reason / D. Definition / 6. Definition by Essence
 19291 A canonical defintion specifies the type of thing, and what distinguish this specimen
###### 4. Formal Logic / D. Modal Logic ML / 7. Barcan Formula
 19301 With a negative free logic, we can dispense with the Barcan formulae
 19297 The two Barcan principles are easily proved in fairly basic modal logic
###### 5. Theory of Logic / A. Overview of Logic / 7. Second-Order Logic
 19296 If second-order variables range over sets, those are just objects; properties and relations aren't sets
###### 5. Theory of Logic / C. Ontology of Logic / 4. Logic by Convention
 19289 Maybe conventionalism applies to meaning, but not to the truth of propositions expressed
###### 5. Theory of Logic / H. Proof Systems / 4. Natural Deduction
 19298 Unlike axiom proofs, natural deduction proofs needn't focus on logical truths and theorems
###### 6. Mathematics / C. Sources of Mathematics / 6. Logicism / c. Neo-logicism
 19295 Add Hume's principle to logic, to get numbers; arithmetic truths rest on the nature of the numbers
###### 7. Existence / C. Structure of Existence / 5. Supervenience / a. Nature of supervenience
 19281 Interesting supervenience must characterise the base quite differently from what supervenes on it
###### 7. Existence / D. Theories of Reality / 7. Facts / c. Facts and truths
 19278 There is no gap between a fact that p, and it is true that p; so we only have the truth-condtions for p
###### 9. Objects / C. Structure of Objects / 5. Composition of an Object
 19302 If a chair could be made of slightly different material, that could lead to big changes
###### 10. Modality / A. Necessity / 3. Types of Necessity
 19290 Absolute necessities are necessarily necessary
 19286 'Absolute necessity' is when there is no restriction on the things which necessitate p
 19288 Logical and metaphysical necessities differ in their vocabulary, and their underlying entities
###### 10. Modality / A. Necessity / 6. Logical Necessity
 19285 Logical necessity is something which is true, no matter what else is the case
 19287 Maybe each type of logic has its own necessity, gradually becoming broader
###### 10. Modality / C. Sources of Modality / 1. Sources of Necessity
 19282 It seems that we cannot show that modal facts depend on non-modal facts
###### 10. Modality / C. Sources of Modality / 6. Necessity from Essence
 19276 The big challenge for essentialist views of modality is things having necessary existence
 19293 Essentialism doesn't explain necessity reductively; it explains all necessities in terms of a few basic natures
 19294 If necessity derives from essences, how do we explain the necessary existence of essences?
###### 10. Modality / E. Possible worlds / 1. Possible Worlds / a. Possible worlds
 19279 What are these worlds, that being true in all of them makes something necessary?
###### 10. Modality / E. Possible worlds / 1. Possible Worlds / e. Against possible worlds
 19299 Possible worlds make every proposition true or false, which endorses classical logic
###### 18. Thought / C. Content / 6. Broad Content
 19300 The molecules may explain the water, but they are not what 'water' means