Combining Texts

All the ideas for 'Thinking About Mathematics', 'Philosophical Logic' and 'Introduction to the Philosophy of Religion'

unexpand these ideas     |    start again     |     specify just one area for these texts


56 ideas

4. Formal Logic / D. Modal Logic ML / 6. Temporal Logic
With four tense operators, all complex tenses reduce to fourteen basic cases [Burgess]
     Full Idea: Fand P as 'will' and 'was', G as 'always going to be', H as 'always has been', all tenses reduce to 14 cases: the past series, each implying the next, FH,H,PH,HP,P,GP, and the future series PG,G,FG,GF,F,HF, plus GH=HG implying all, FP=PF which all imply.
     From: John P. Burgess (Philosophical Logic [2009], 2.8)
     A reaction: I have tried to translate the fourteen into English, but am not quite confident enough to publish them here. I leave it as an exercise for the reader.
4. Formal Logic / D. Modal Logic ML / 7. Barcan Formula
The temporal Barcan formulas fix what exists, which seems absurd [Burgess]
     Full Idea: In temporal logic, if the converse Barcan formula holds then nothing goes out of existence, and the direct Barcan formula holds if nothing ever comes into existence. These results highlight the intuitive absurdity of the Barcan formulas.
     From: John P. Burgess (Philosophical Logic [2009], 2.9)
     A reaction: This is my reaction to the modal cases as well - the absurdity of thinking that no actually nonexistent thing might possibly have existed, or that the actual existents might not have existed. Williamson seems to be the biggest friend of the formulas.
4. Formal Logic / E. Nonclassical Logics / 2. Intuitionist Logic
Is classical logic a part of intuitionist logic, or vice versa? [Burgess]
     Full Idea: From one point of view intuitionistic logic is a part of classical logic, missing one axiom, from another classical logic is a part of intuitionistic logic, missing two connectives, intuitionistic v and →
     From: John P. Burgess (Philosophical Logic [2009], 6.4)
It is still unsettled whether standard intuitionist logic is complete [Burgess]
     Full Idea: The question of the completeness of the full intuitionistic logic for its intended interpretation is not yet fully resolved.
     From: John P. Burgess (Philosophical Logic [2009], 6.9)
4. Formal Logic / E. Nonclassical Logics / 5. Relevant Logic
Relevance logic's → is perhaps expressible by 'if A, then B, for that reason' [Burgess]
     Full Idea: The relevantist logician's → is perhaps expressible by 'if A, then B, for that reason'.
     From: John P. Burgess (Philosophical Logic [2009], 5.8)
5. Theory of Logic / A. Overview of Logic / 4. Pure Logic
Technical people see logic as any formal system that can be studied, not a study of argument validity [Burgess]
     Full Idea: Among the more technically oriented a 'logic' no longer means a theory about which forms of argument are valid, but rather means any formalism, regardless of its applications, that resembles original logic enough to be studied by similar methods.
     From: John P. Burgess (Philosophical Logic [2009], Pref)
     A reaction: There doesn't seem to be any great intellectual obligation to be 'technical'. As far as pure logic is concerned, I am very drawn to the computer approach, since I take that to be the original dream of Aristotle and Leibniz - impersonal precision.
5. Theory of Logic / A. Overview of Logic / 6. Classical Logic
Classical logic neglects the non-mathematical, such as temporality or modality [Burgess]
     Full Idea: There are topics of great philosophical interest that classical logic neglects because they are not important to mathematics. …These include distinctions of past, present and future, or of necessary, actual and possible.
     From: John P. Burgess (Philosophical Logic [2009], 1.1)
Classical logic neglects counterfactuals, temporality and modality, because maths doesn't use them [Burgess]
     Full Idea: Classical logic neglects counterfactual conditionals for the same reason it neglects temporal and modal distinctions, namely, that they play no serious role in mathematics.
     From: John P. Burgess (Philosophical Logic [2009], 4.1)
     A reaction: Science obviously needs counterfactuals, and metaphysics needs modality. Maybe so-called 'classical' logic will be renamed 'basic mathematical logic'. Philosophy will become a lot clearer when that happens.
The Cut Rule expresses the classical idea that entailment is transitive [Burgess]
     Full Idea: The Cut rule (from A|-B and B|-C, infer A|-C) directly expresses the classical doctrine that entailment is transitive.
     From: John P. Burgess (Philosophical Logic [2009], 5.3)
5. Theory of Logic / A. Overview of Logic / 9. Philosophical Logic
Philosophical logic is a branch of logic, and is now centred in computer science [Burgess]
     Full Idea: Philosophical logic is a branch of logic, a technical subject. …Its centre of gravity today lies in theoretical computer science.
     From: John P. Burgess (Philosophical Logic [2009], Pref)
     A reaction: He firmly distinguishes it from 'philosophy of logic', but doesn't spell it out. I take it that philosophical logic concerns metaprinciples which compare logical systems, and suggest new lines of research. Philosophy of logic seems more like metaphysics.
5. Theory of Logic / D. Assumptions for Logic / 2. Excluded Middle
Intuitionists deny excluded middle, because it is committed to transcendent truth or objects [Shapiro]
     Full Idea: Intuitionists in mathematics deny excluded middle, because it is symptomatic of faith in the transcendent existence of mathematical objects and/or the truth of mathematical statements.
     From: Stewart Shapiro (Thinking About Mathematics [2000], 1.2)
     A reaction: There are other problems with excluded middle, such as vagueness, but on the whole I, as a card-carrying 'realist', am committed to the law of excluded middle.
5. Theory of Logic / E. Structures of Logic / 2. Logical Connectives / a. Logical connectives
Formalising arguments favours lots of connectives; proving things favours having very few [Burgess]
     Full Idea: When formalising arguments it is convenient to have as many connectives as possible available.; but when proving results about formulas it is convenient to have as few as possible.
     From: John P. Burgess (Philosophical Logic [2009], 1.4)
     A reaction: Illuminating. The fact that you can whittle classical logic down to two (or even fewer!) connectives warms the heart of technicians, but makes connection to real life much more difficult. Hence a bunch of extras get added.
5. Theory of Logic / E. Structures of Logic / 2. Logical Connectives / e. or
Asserting a disjunction from one disjunct seems odd, but can be sensible, and needed in maths [Burgess]
     Full Idea: Gricean implicature theory might suggest that a disjunction is never assertable when a disjunct is (though actually the disjunction might be 'pertinent') - but the procedure is indispensable in mathematical practice.
     From: John P. Burgess (Philosophical Logic [2009], 5.2)
     A reaction: He gives an example of a proof in maths which needs it, and an unusual conversational occasion where it makes sense.
5. Theory of Logic / E. Structures of Logic / 4. Variables in Logic
All occurrences of variables in atomic formulas are free [Burgess]
     Full Idea: All occurrences of variables in atomic formulas are free.
     From: John P. Burgess (Philosophical Logic [2009], 1.7)
5. Theory of Logic / F. Referring in Logic / 2. Descriptions / b. Definite descriptions
The denotation of a definite description is flexible, rather than rigid [Burgess]
     Full Idea: By contrast to rigidly designating proper names, …the denotation of definite descriptions is (in general) not rigid but flexible.
     From: John P. Burgess (Philosophical Logic [2009], 2.9)
     A reaction: This modern way of putting it greatly clarifies why Russell was interested in the type of reference involved in definite descriptions. Obviously some descriptions (such as 'the only person who could ever have…') might be rigid.
5. Theory of Logic / H. Proof Systems / 1. Proof Systems
'Induction' and 'recursion' on complexity prove by connecting a formula to its atomic components [Burgess]
     Full Idea: There are atomic formulas, and formulas built from the connectives, and that is all. We show that all formulas have some property, first for the atomics, then the others. This proof is 'induction on complexity'; we also use 'recursion on complexity'.
     From: John P. Burgess (Philosophical Logic [2009], 1.4)
     A reaction: That is: 'induction on complexity' builds a proof from atomics, via connectives; 'recursion on complexity' breaks down to the atomics, also via the connectives. You prove something by showing it is rooted in simple truths.
5. Theory of Logic / H. Proof Systems / 6. Sequent Calculi
The sequent calculus makes it possible to have proof without transitivity of entailment [Burgess]
     Full Idea: It might be wondered how one could have any kind of proof procedure at all if transitivity of entailment is disallowed, but the sequent calculus can get around the difficulty.
     From: John P. Burgess (Philosophical Logic [2009], 5.3)
     A reaction: He gives examples where transitivity of entailment (so that you can build endless chains of deductions) might fail. This is the point of the 'cut free' version of sequent calculus, since the cut rule allows transitivity.
We can build one expanding sequence, instead of a chain of deductions [Burgess]
     Full Idea: Instead of demonstrations which are either axioms, or follow from axioms by rules, we can have one ever-growing sequence of formulas of the form 'Axioms |- ______', where the blank is filled by Axioms, then Lemmas, then Theorems, then Corollaries.
     From: John P. Burgess (Philosophical Logic [2009], 5.3)
5. Theory of Logic / I. Semantics of Logic / 3. Logical Truth
'Tautologies' are valid formulas of classical sentential logic - or substitution instances in other logics [Burgess]
     Full Idea: The valid formulas of classical sentential logic are called 'tautologically valid', or simply 'tautologies'; with other logics 'tautologies' are formulas that are substitution instances of valid formulas of classical sentential logic.
     From: John P. Burgess (Philosophical Logic [2009], 1.5)
5. Theory of Logic / I. Semantics of Logic / 4. Satisfaction
Validity (for truth) and demonstrability (for proof) have correlates in satisfiability and consistency [Burgess]
     Full Idea: Validity (truth by virtue of logical form alone) and demonstrability (provability by virtue of logical form alone) have correlative notions of logical possibility, 'satisfiability' and 'consistency', which come apart in some logics.
     From: John P. Burgess (Philosophical Logic [2009], 3.3)
5. Theory of Logic / J. Model Theory in Logic / 1. Logical Models
We only need to study mathematical models, since all other models are isomorphic to these [Burgess]
     Full Idea: In practice there is no need to consider any but mathematical models, models whose universes consist of mathematical objects, since every model is isomorphic to one of these.
     From: John P. Burgess (Philosophical Logic [2009], 1.8)
     A reaction: The crucial link is the technique of Gödel Numbering, which can translate any verbal formula into numerical form. He adds that, because of the Löwenheim-Skolem theorem only subsets of the natural numbers need be considered.
Models leave out meaning, and just focus on truth values [Burgess]
     Full Idea: Models generally deliberately leave out meaning, retaining only what is important for the determination of truth values.
     From: John P. Burgess (Philosophical Logic [2009], 2.2)
     A reaction: This is the key point to hang on to, if you are to avoid confusing mathematical models with models of things in the real world.
We aim to get the technical notion of truth in all models matching intuitive truth in all instances [Burgess]
     Full Idea: The aim in setting up a model theory is that the technical notion of truth in all models should agree with the intuitive notion of truth in all instances. A model is supposed to represent everything about an instance that matters for its truth.
     From: John P. Burgess (Philosophical Logic [2009], 3.2)
5. Theory of Logic / L. Paradox / 6. Paradoxes in Language / a. The Liar paradox
The Liar seems like a truth-value 'gap', but dialethists see it as a 'glut' [Burgess]
     Full Idea: It is a common view that the liar sentence ('This very sentence is not true') is an instance of a truth-value gap (neither true nor false), but some dialethists cite it as an example of a truth-value glut (both true and false).
     From: John P. Burgess (Philosophical Logic [2009], 5.7)
     A reaction: The defence of the glut view must be that it is true, then it is false, then it is true... Could it manage both at once?
6. Mathematics / A. Nature of Mathematics / 3. Nature of Numbers / b. Types of number
The number 3 is presumably identical as a natural, an integer, a rational, a real, and complex [Shapiro]
     Full Idea: It is surely wise to identify the positions in the natural numbers structure with their counterparts in the integer, rational, real and complex number structures.
     From: Stewart Shapiro (Thinking About Mathematics [2000], 10.2)
     A reaction: The point is that this might be denied, since 3, 3/1, 3.00.., and -3*i^2 are all arrived at by different methods of construction. Natural 3 has a predecessor, but real 3 doesn't. I agree, intuitively, with Shapiro. Russell (1919) disagreed.
6. Mathematics / A. Nature of Mathematics / 3. Nature of Numbers / h. Reals from Cauchy
Cauchy gave a formal definition of a converging sequence. [Shapiro]
     Full Idea: A sequence a1,a2,... of rational numbers is 'Cauchy' if for each rational number ε>0 there is a natural number N such that for all natural numbers m, n, if m>N and n>N then -ε < am - an < ε.
     From: Stewart Shapiro (Thinking About Mathematics [2000], 7.2 n4)
     A reaction: The sequence is 'Cauchy' if N exists.
6. Mathematics / B. Foundations for Mathematics / 1. Foundations for Mathematics
Categories are the best foundation for mathematics [Shapiro]
     Full Idea: There is a dedicated contingent who hold that the category of 'categories' is the proper foundation for mathematics.
     From: Stewart Shapiro (Thinking About Mathematics [2000], 10.3 n7)
     A reaction: He cites Lawvere (1966) and McLarty (1993), the latter presenting the view as a form of structuralism. I would say that the concept of a category will need further explication, and probably reduce to either sets or relations or properties.
6. Mathematics / B. Foundations for Mathematics / 5. Definitions of Number / f. Zermelo numbers
Two definitions of 3 in terms of sets disagree over whether 1 is a member of 3 [Shapiro]
     Full Idea: Zermelo said that for each number n, its successor is the singleton of n, so 3 is {{{null}}}, and 1 is not a member of 3. Von Neumann said each number n is the set of numbers less than n, so 3 is {null,{null},{null,{null}}}, and 1 is a member of 3.
     From: Stewart Shapiro (Thinking About Mathematics [2000], 10.2)
     A reaction: See Idea 645 - Zermelo could save Plato from the criticisms of Aristotle! These two accounts are cited by opponents of the set-theoretical account of numbers, because it seems impossible to arbitrate between them.
6. Mathematics / B. Foundations for Mathematics / 7. Mathematical Structuralism / a. Structuralism
Numbers do not exist independently; the essence of a number is its relations to other numbers [Shapiro]
     Full Idea: The structuralist vigorously rejects any sort of ontological independence among the natural numbers; the essence of a natural number is its relations to other natural numbers.
     From: Stewart Shapiro (Thinking About Mathematics [2000], 10.1)
     A reaction: This seems to place the emphasis on ordinals (what order?) rather than on cardinality (how many?). I am strongly inclined to think that this is the correct view, though you can't really have relations if there is nothing to relate.
A 'system' is related objects; a 'pattern' or 'structure' abstracts the pure relations from them [Shapiro]
     Full Idea: A 'system' is a collection of objects with certain relations among them; a 'pattern' or 'structure' is the abstract form of a system, highlighting the interrelationships and ignoring any features they do not affect how they relate to other objects.
     From: Stewart Shapiro (Thinking About Mathematics [2000], 10.1)
     A reaction: Note that 'ignoring' features is a psychological account of abstraction, which (thanks to Frege and Geach) is supposed to be taboo - but which I suspect is actually indispensable in any proper account of thought and concepts.
6. Mathematics / C. Sources of Mathematics / 6. Logicism / d. Logicism critique
Logicism seems to be a non-starter if (as is widely held) logic has no ontology of its own [Shapiro]
     Full Idea: The thesis that principles of arithmetic are derivable from the laws of logic runs against a now common view that logic itself has no ontology. There are no particular logical objects. From this perspective logicism is a non-starter.
     From: Stewart Shapiro (Thinking About Mathematics [2000], 5.1)
     A reaction: This criticism strikes me as utterly devastating. There are two routes to go: prove that logic does have an ontology of objects (what would they be?), or - better - deny that arithmetic contains any 'objects'. Or give up logicism.
6. Mathematics / C. Sources of Mathematics / 7. Formalism
Term Formalism says mathematics is just about symbols - but real numbers have no names [Shapiro]
     Full Idea: Term Formalism is the view that mathematics is just about characters or symbols - the systems of numerals and other linguistic forms. ...This will cover integers and rational numbers, but what are real numbers supposed to be, if they lack names?
     From: Stewart Shapiro (Thinking About Mathematics [2000], 6.1.1)
     A reaction: Real numbers (such as pi and root-2) have infinite decimal expansions, so we can start naming those. We could also start giving names like 'Harry' to other reals, though it might take a while. OK, I give up.
Game Formalism is just a matter of rules, like chess - but then why is it useful in science? [Shapiro]
     Full Idea: Game Formalism likens mathematics to chess, where the 'content' of mathematics is exhausted by the rules of operating with its language. ...This, however, leaves the problem of why the mathematical games are so useful to the sciences.
     From: Stewart Shapiro (Thinking About Mathematics [2000], 6.1.2)
     A reaction: This thought pushes us towards structuralism. It could still be a game, but one we learned from observing nature, which plays its own games. Chess is, after all, modelled on warfare.
Deductivism says mathematics is logical consequences of uninterpreted axioms [Shapiro]
     Full Idea: The Deductivist version of formalism (sometimes called 'if-thenism') says that the practice of mathematics consists of determining logical consequences of otherwise uninterpreted axioms.
     From: Stewart Shapiro (Thinking About Mathematics [2000], 6.2)
     A reaction: [Hilbert is the source] More plausible than Term or Game Formalism (qv). It still leaves the question of why it seems applicable to nature, and why those particular axioms might be chosen. In some sense, though, it is obviously right.
6. Mathematics / C. Sources of Mathematics / 10. Constructivism / b. Intuitionism
Critics resent the way intuitionism cripples mathematics, but it allows new important distinctions [Shapiro]
     Full Idea: Critics commonly complain that the intuitionist restrictions cripple the mathematician. On the other hand, intuitionist mathematics allows for many potentially important distinctions not available in classical mathematics, and is often more subtle.
     From: Stewart Shapiro (Thinking About Mathematics [2000], 7.1)
     A reaction: The main way in which it cripples is its restriction on talk of infinity ('Cantor's heaven'), which was resented by Hilbert. Since high-level infinities are interesting, it would be odd if we were not allowed to discuss them.
6. Mathematics / C. Sources of Mathematics / 10. Constructivism / c. Conceptualism
Conceptualist are just realists or idealist or nominalists, depending on their view of concepts [Shapiro]
     Full Idea: I classify conceptualists according to what they say about properties or concepts. If someone classified properties as existing independent of language I would classify her as a realist in ontology of mathematics. Or they may be idealists or nominalists.
     From: Stewart Shapiro (Thinking About Mathematics [2000], 2.2.1)
     A reaction: In other words, Shapiro wants to eliminate 'conceptualist' as a useful label in philosophy of mathematics. He's probably right. All thought involves concepts, but that doesn't produce a conceptualist theory of, say, football.
6. Mathematics / C. Sources of Mathematics / 10. Constructivism / d. Predicativism
'Impredicative' definitions refer to the thing being described [Shapiro]
     Full Idea: A definition of a mathematical entity is 'impredicative' if it refers to a collection that contains the defined entity. The definition of 'least upper bound' is impredicative as it refers to upper bounds and characterizes a member of this set.
     From: Stewart Shapiro (Thinking About Mathematics [2000], 1.2)
     A reaction: The big question is whether mathematics can live with impredicative definitions, or whether they threaten to be viciously circular, and undermine the whole enterprise.
10. Modality / A. Necessity / 4. De re / De dicto modality
De re modality seems to apply to objects a concept intended for sentences [Burgess]
     Full Idea: There is a problem over 'de re' modality (as contrasted with 'de dicto'), as in ∃x□x. What is meant by '"it is analytic that Px" is satisfied by a', given that analyticity is a notion that in the first instance applies to complete sentences?
     From: John P. Burgess (Philosophical Logic [2009], 3.9)
     A reaction: This is Burgess's summary of one of Quine's original objections. The issue may be a distinction between whether the sentence is analytic, and what makes it analytic. The necessity of bachelors being unmarried makes that sentence analytic.
10. Modality / A. Necessity / 6. Logical Necessity
General consensus is S5 for logical modality of validity, and S4 for proof [Burgess]
     Full Idea: To the extent that there is any conventional wisdom about the question, it is that S5 is correct for alethic logical modality, and S4 correct for apodictic logical modality.
     From: John P. Burgess (Philosophical Logic [2009], 3.8)
     A reaction: In classical logic these coincide, so presumably one should use the minimum system to do the job, which is S4 (?).
Logical necessity has two sides - validity and demonstrability - which coincide in classical logic [Burgess]
     Full Idea: Logical necessity is a genus with two species. For classical logic the truth-related notion of validity and the proof-related notion of demonstrability, coincide - but they are distinct concept. In some logics they come apart, in intension and extension.
     From: John P. Burgess (Philosophical Logic [2009], 3.3)
     A reaction: They coincide in classical logic because it is sound and complete. This strikes me as the correct approach to logical necessity, tying it to the actual nature of logic, rather than some handwavy notion of just 'true in all possible worlds'.
10. Modality / B. Possibility / 8. Conditionals / a. Conditionals
Three conditionals theories: Materialism (material conditional), Idealism (true=assertable), Nihilism (no truth) [Burgess]
     Full Idea: Three main theories of the truth of indicative conditionals are Materialism (the conditions are the same as for the material conditional), Idealism (identifying assertability with truth-value), and Nihilism (no truth, just assertability).
     From: John P. Burgess (Philosophical Logic [2009], 4.3)
It is doubtful whether the negation of a conditional has any clear meaning [Burgess]
     Full Idea: It is contentious whether conditionals have negations, and whether 'it is not the case that if A,B' has any clear meaning.
     From: John P. Burgess (Philosophical Logic [2009], 4.9)
     A reaction: This seems to be connected to Lewis's proof that a probability conditional cannot be reduced to a single proposition. If a conditional only applies to A-worlds, it is not surprising that its meaning gets lost when it leaves that world.
12. Knowledge Sources / C. Rationalism / 1. Rationalism
Rationalism tries to apply mathematical methodology to all of knowledge [Shapiro]
     Full Idea: Rationalism is a long-standing school that can be characterized as an attempt to extend the perceived methodology of mathematics to all of knowledge.
     From: Stewart Shapiro (Thinking About Mathematics [2000], 1.1)
     A reaction: Sometimes called 'Descartes's Dream', or the 'Enlightenment Project', the dream of proving everything. Within maths, Hilbert's Programme aimed for the same certainty. Idea 22 is the motto for the opposition to this approach.
28. God / A. Divine Nature / 5. God and Time
God is 'eternal' either by being non-temporal, or by enduring forever [Davies,B]
     Full Idea: Saying 'God is eternal' means either that God is non-temporal or timeless, or that God has no beginning and no end. The first ('classical') view is found in Anselm, Augustine, Boethius, Aquinas, Calvin and Descartes.
     From: Brian Davies (Introduction to the Philosophy of Religion [1982], 8 'Meaning')
     A reaction: A God who is outside of time but performs actions is a bit of a puzzle. It seems that Augustine started the idea of a timeless God.
28. God / A. Divine Nature / 6. Divine Morality / a. Divine morality
Can God be good, if he has not maximised goodness? [Davies,B]
     Full Idea: We may wonder whether God can be good since he has not produced more moral goodness than he has. We may wonder whether God is guilty by neglect.
     From: Brian Davies (Introduction to the Philosophy of Religion [1982], 3 'Freedom')
     A reaction: The orthodox response is that we cannot possibly know what the maximum of moral goodness would look like, so we can't make this judgement. Atheists say that God fails by human standards, which are not particularly high.
28. God / A. Divine Nature / 6. Divine Morality / c. God is the good
The goodness of God may be a higher form than the goodness of moral agents [Davies,B]
     Full Idea: If we can know that God exists and if God's goodness is not moral goodness, then moral goodness is not the highest form of goodness we know. There is the goodness of God to be reckoned with.
     From: Brian Davies (Introduction to the Philosophy of Religion [1982], 3 'Goodness')
     A reaction: This idea is to counter the charge that God fails to meet human standards for an ideal moral agent. But it sounds hand-wavy, since we presumably cannot comprehend the sort of goodness that is postulated here.
28. God / A. Divine Nature / 6. Divine Morality / d. God decrees morality
How could God have obligations? What law could possibly impose them? [Davies,B]
     Full Idea: We have good reason for resisting the suggestion that God has any duties or obligations. …What can oblige God in relation to his creatures? Could there be a law saying God has such obligations? Where does such a law come from?
     From: Brian Davies (Introduction to the Philosophy of Religion [1982], 3 'Goodness')
     A reaction: Plato can answer this question. Greek gods are not so supreme that nothing could put them under an obligation, but 'God' has to be supreme in every respect.
28. God / B. Proving God / 1. Proof of God
'Natural theology' aims to prove God to anyone (not just believers) by reason or argument [Davies,B]
     Full Idea: 'Natural theology' is the attempt to show that belief in God's existence can be defended with reference to reason or argument which ought to be acceptable to anyone, not simply to those who believe in God's existence.
     From: Brian Davies (Introduction to the Philosophy of Religion [1982], 1 'Other')
     A reaction: I assume by 'reason or argument' he primarily means evidence (plus the ontological argument). He cites Karl Barth as objecting to the assumption of natural theology (preferring revelation). Presumably Kierkegaard offers a rival view too.
28. God / B. Proving God / 3. Proofs of Evidence / a. Cosmological Proof
A distinct cause of the universe can't be material (which would be part of the universe) [Davies,B]
     Full Idea: If the universe was caused to come into being, it presumably could not have been caused to do so by anything material. For a material object would be part of the universe, and we are now asking for a cause distinct from the universe.
     From: Brian Davies (Introduction to the Philosophy of Religion [1982], 5 'God')
     A reaction: We're out of our depth here. We only have two modes of existence to offer, material and spiritual, and 'spiritual' means little more than non-material.
28. God / B. Proving God / 3. Proofs of Evidence / b. Teleological Proof
The universe exhibits design either in its sense of purpose, or in its regularity [Davies,B]
     Full Idea: The design argument offers two lines: the first states that the universe displays design in the sense of purpose; the second that it displays design in the sense of regularity.
     From: Brian Davies (Introduction to the Philosophy of Religion [1982], 6 'Versions')
     A reaction: I would have thought that you would infer the purpose from the regularity. How could you see purpose in a totally chaotic universe?
28. God / B. Proving God / 3. Proofs of Evidence / c. Teleological Proof critique
If God is an orderly being, he cannot be the explanation of order [Davies,B]
     Full Idea: If God is an instance of something orderly, how can he serve to account for the order of orderly things?
     From: Brian Davies (Introduction to the Philosophy of Religion [1982], 6 'b Has')
     A reaction: You can at least explain the tidiness of a house by the tidiness of its owner, but obviously that won't explain the phenomenon of tidiness.
28. God / B. Proving God / 3. Proofs of Evidence / d. Religious Experience
Maybe an abnormal state of mind is needed to experience God? [Davies,B]
     Full Idea: Might it not be possible that experience of God requires an unusual state or psychological abnormality, just as an aerial view of Paris requires that one be in the unusual state of being abnormally elevated?
     From: Brian Davies (Introduction to the Philosophy of Religion [1982], 7 'Are the')
     A reaction: That would make sense if it were analogous to great mathematical or musical ability, but it sounds more like ouija boards in darkened rooms. Talent has a wonderful output, but people in mystical states don't return with proofs.
A believer can experience the world as infused with God [Davies,B]
     Full Idea: Maybe someone who believes in God can be regarded as experiencing everything as something behind which God lies. Believers see the world as a world in which God is present.
     From: Brian Davies (Introduction to the Philosophy of Religion [1982], 7 'Experiencing')
     A reaction: [Attributed to John Hick] This would count as supporting evidence for God, perhaps, if seeing reality as infused with God produces a consistent and plausible picture. But seeing reality as infused with other things might pass the same test.
The experiences of God are inconsistent, not universal, and untestable [Davies,B]
     Full Idea: A proclaimed experience of God must be rejected because a) there is no agreed test that it is such an experience, b) some people experience God's absence, and c) there is no uniformity of testimony about the experience.
     From: Brian Davies (Introduction to the Philosophy of Religion [1982], 7 'Objections')
     A reaction: [compressed] I'm not sure that absence of an experience is experience of an absence. Compare it with experiencing the greatness of Beethoven's Ninth.
29. Religion / D. Religious Issues / 1. Religious Commitment / b. Religious Meaning
One does not need a full understanding of God in order to speak of God [Davies,B]
     Full Idea: In order to speak meaningfully about God, it is not necessary that one should understand exactly the import of one's statements about him.
     From: Brian Davies (Introduction to the Philosophy of Religion [1982], 2 'Sayng')
     A reaction: Perfectly reasonable. To insist that all discussion of a thing requires exact understanding of the thing is ridiculous. Equally, though, to discuss God while denying all understanding of God is just as ridiculous.
29. Religion / D. Religious Issues / 2. Immortality / d. Heaven
Paradise would not contain some virtues, such as courage [Davies,B]
     Full Idea: There are virtues (such as courage) that would not be present in a paradise.
     From: Brian Davies (Introduction to the Philosophy of Religion [1982], 3 'Evil')
     A reaction: Part of a suggestion that morality would be entirely inapplicable in paradise, and so we need dangers etc in the world.