Combining Philosophers

All the ideas for Brad W. Hooker, Charles Darwin and Oliver,A/Smiley,T

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17 ideas

4. Formal Logic / F. Set Theory ST / 3. Types of Set / b. Empty (Null) Set
The empty set is usually derived from Separation, but it also seems to need Infinity [Oliver/Smiley]
     Full Idea: The empty set is usually derived via Zermelo's axiom of separation. But the axiom of separation is conditional: it requires the existence of a set in order to generate others as subsets of it. The original set has to come from the axiom of infinity.
     From: Oliver,A/Smiley,T (What are Sets and What are they For? [2006], 1.2)
     A reaction: They charge that this leads to circularity, as Infinity depends on the empty set.
The empty set is something, not nothing! [Oliver/Smiley]
     Full Idea: Some authors need to be told loud and clear: if there is an empty set, it is something, not nothing.
     From: Oliver,A/Smiley,T (What are Sets and What are they For? [2006], 1.2)
     A reaction: I'm inclined to think of a null set as a pair of brackets, so maybe that puts it into a metalanguage.
We don't need the empty set to express non-existence, as there are other ways to do that [Oliver/Smiley]
     Full Idea: The empty set is said to be useful to express non-existence, but saying 'there are no Us', or ¬∃xUx are no less concise, and certainly less roundabout.
     From: Oliver,A/Smiley,T (What are Sets and What are they For? [2006], 1.2)
Maybe we can treat the empty set symbol as just meaning an empty term [Oliver/Smiley]
     Full Idea: Suppose we introduce Ω not as a term standing for a supposed empty set, but as a paradigm of an empty term, not standing for anything.
     From: Oliver,A/Smiley,T (What are Sets and What are they For? [2006], 1.2)
     A reaction: This proposal, which they go on to explore, seems to mean that Ω (i.e. the traditional empty set symbol) is no longer part of set theory but is part of semantics.
4. Formal Logic / F. Set Theory ST / 3. Types of Set / c. Unit (Singleton) Sets
The unit set may be needed to express intersections that leave a single member [Oliver/Smiley]
     Full Idea: Thomason says with no unit sets we couldn't call {1,2}∩{2,3} a set - but so what? Why shouldn't the intersection be the number 2? However, we then have to distinguish three different cases of intersection (common subset or member, or disjoint).
     From: Oliver,A/Smiley,T (What are Sets and What are they For? [2006], 2.2)
5. Theory of Logic / G. Quantification / 6. Plural Quantification
If you only refer to objects one at a time, you need sets in order to refer to a plurality [Oliver/Smiley]
     Full Idea: A 'singularist', who refers to objects one at a time, must resort to the language of sets in order to replace plural reference to members ('Henry VIII's wives') by singular reference to a set ('the set of Henry VIII's wives').
     From: Oliver,A/Smiley,T (What are Sets and What are they For? [2006], Intro)
     A reaction: A simple and illuminating point about the motivation for plural reference. Null sets and singletons give me the creeps, so I would personally prefer to avoid set theory when dealing with ontology.
We can use plural language to refer to the set theory domain, to avoid calling it a 'set' [Oliver/Smiley]
     Full Idea: Plurals earn their keep in set theory, to answer Skolem's remark that 'in order to treat of 'sets', we must begin with 'domains' that are constituted in a certain way'. We can speak in the plural of 'the objects', not a 'domain' of objects.
     From: Oliver,A/Smiley,T (What are Sets and What are they For? [2006], Intro)
     A reaction: [Skolem 1922:291 in van Heijenoort] Zermelo has said that the domain cannot be a set, because every set belongs to it.
5. Theory of Logic / I. Semantics of Logic / 3. Logical Truth
Logical truths are true no matter what exists - but predicate calculus insists that something exists [Oliver/Smiley]
     Full Idea: Logical truths should be true no matter what exists, so true even if nothing exists. The classical predicate calculus, however, makes it logically true that something exists.
     From: Oliver,A/Smiley,T (What are Sets and What are they For? [2006], 5.1)
6. Mathematics / A. Nature of Mathematics / 4. Using Numbers / g. Applying mathematics
If mathematics purely concerned mathematical objects, there would be no applied mathematics [Oliver/Smiley]
     Full Idea: If mathematics was purely concerned with mathematical objects, there would be no room for applied mathematics.
     From: Oliver,A/Smiley,T (What are Sets and What are they For? [2006], 5.1)
     A reaction: Love it! Of course, they are using 'objects' in the rather Fregean sense of genuine abstract entities. I don't see why fictionalism shouldn't allow maths to be wholly 'pure', although we have invented fictions which actually have application.
6. Mathematics / B. Foundations for Mathematics / 6. Mathematics as Set Theory / a. Mathematics is set theory
Sets might either represent the numbers, or be the numbers, or replace the numbers [Oliver/Smiley]
     Full Idea: Identifying numbers with sets may mean one of three quite different things: 1) the sets represent the numbers, or ii) they are the numbers, or iii) they replace the numbers.
     From: Oliver,A/Smiley,T (What are Sets and What are they For? [2006], 5.2)
     A reaction: Option one sounds the most plausible to me. I will take numbers to be patterns embedded in nature, and sets are one way of presenting them in shorthand form, in order to bring out what is repeated.
14. Science / D. Explanation / 3. Best Explanation / a. Best explanation
A false theory could hardly rival the explanatory power of natural selection [Darwin]
     Full Idea: It can hardly be supposed that a false theory would explain, in so satisfactory a manner as does the theory of natural selection, the several large classes of facts above specified.
     From: Charles Darwin (The Origin of the Species [1859], p.476), quoted by Peter Lipton - Inference to the Best Explanation (2nd) 11 'The scientific'
     A reaction: More needs to be said, since the whims of God could explain absolutely everything (in a manner that would be somehow less that fully satisfying to the enquiring intellect).
22. Metaethics / A. Ethics Foundations / 2. Source of Ethics / i. Prescriptivism
Prescriptivism says 'ought' without commitment to act is insincere, or weakly used [Hooker,B]
     Full Idea: Prescriptivism holds that if you think one 'ought' to do a certain kind of act, and yet you are not committed to doing that act in the relevant circumstances, then you either spoke insincerely, or are using the word 'ought' in a weak sense.
     From: Brad W. Hooker (Prescriptivism [1995], p.640)
     A reaction: So that's an 'ought', but not a 'genuine ought', then? (No True Scotsman move). Someone ought to rescue that drowning child, but I can't be bothered.
23. Ethics / B. Contract Ethics / 2. Golden Rule
Universal moral judgements imply the Golden Rule ('do as you would be done by') [Hooker,B]
     Full Idea: Prescriptivity is especially important if moral judgements are universalizable, for then we can employ golden rule-style reasoning ('do as you would be done by').
     From: Brad W. Hooker (Prescriptivism [1995], p.640)
23. Ethics / E. Utilitarianism / 2. Ideal of Pleasure
Modern utilitarians value knowledge, friendship, autonomy, and achievement, as well as pleasure [Hooker,B]
     Full Idea: Most utilitarians now think that pleasure, even if construed widely, is not the only thing desirable in itself. ...Goods also include important knowledge, friendship, autonomy, achievement and so on.
     From: Brad W. Hooker (Rule Utilitarianism and Euthanasia [1997], 2)
     A reaction: That pleasure is desired is empirically verifiable, which certainly motivated Bentham. A string of other desirables each needs to be justified - but how? What would be the value of a 'friendship' if neither party got pleasure from it?
23. Ethics / E. Utilitarianism / 5. Rule Utilitarianism
Rule-utilitarians prevent things like torture, even on rare occasions when it seems best [Hooker,B]
     Full Idea: For rule-utilitarians acts of murder, torture and so on, can be impermissible even in rare cases where they really would produce better consequences than any alternative act.
     From: Brad W. Hooker (Rule Utilitarianism and Euthanasia [1997], 4)
     A reaction: It is basic to rule-utilitarianism that it trumps act-ulitilarianism, even when a particular act wins the utilitarian calculation. But that is hard to understand. Only long-term benefit could justify the rule - but that should win the calculation.
25. Social Practice / F. Life Issues / 2. Euthanasia
Euthanasia is active or passive, and voluntary, non-voluntary or involuntary [Hooker,B]
     Full Idea: Six types of euthanasia: 1) Active voluntary (knowing my wishes), 2) Active non-voluntary (not knowing my wishes), 3) Active involuntary (against my wishes), 4) Passive voluntary, 5) Passive non-voluntary, 6) Passive involuntary.
     From: Brad W. Hooker (Rule Utilitarianism and Euthanasia [1997], 5)
     A reaction: 'Active' is intervening, and 'passive' is not intervening. A helpful framework.
Euthanasia may not involve killing, so it is 'killing or not saving, out of concern for that person' [Hooker,B]
     Full Idea: Passive euthanasia is arguably not killing, and the death involved is often painful, so let us take the term 'euthanasia' to mean 'either killing or passing up opportunities to save someone, out of concern for that person'.
     From: Brad W. Hooker (Rule Utilitarianism and Euthanasia [1997], 1)
     A reaction: This sounds good, and easily settled, until you think concern for that person could have two different outcomes, depending on whether the criteria are those of the decider or of the patient. Think of religious decider and atheist patient, or vice versa.