Combining Philosophers

All the ideas for Lynch,MP/Glasgow,JM, J Baggini / PS Fosl and Graham Priest

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59 ideas

2. Reason / B. Laws of Thought / 2. Sufficient Reason
The Principle of Sufficient Reason does not presuppose that all explanations will be causal explanations [Baggini /Fosl]
     Full Idea: The Principle of Sufficient Reason does not presuppose that all explanations will be causal explanations.
     From: J Baggini / PS Fosl (The Philosopher's Toolkit [2003], §3.28)
     A reaction: This sounds a reasonable note of caution, but doesn't carry much weight unless some type of non-causal reason can be envisaged. God's free will? Our free will? The laws of causation?
2. Reason / B. Laws of Thought / 3. Non-Contradiction
Someone standing in a doorway seems to be both in and not-in the room [Priest,G, by Sorensen]
     Full Idea: Priest says there is room for contradictions. He gives the example of someone in a doorway; is he in or out of the room. Given that in and out are mutually exclusive and exhaustive, and neither is the default, he seems to be both in and not in.
     From: report of Graham Priest (What is so bad about Contradictions? [1998]) by Roy Sorensen - Vagueness and Contradiction 4.3
     A reaction: Priest is a clever lad, but I don't think I can go with this. It just seems to be an equivocation on the word 'in' when applied to rooms. First tell me the criteria for being 'in' a room. What is the proposition expressed in 'he is in the room'?
You cannot rationally deny the principle of non-contradiction, because all reasoning requires it [Baggini /Fosl]
     Full Idea: Anyone who denies the principle of non-contradiction simultaneously affirms it; it cannot be rationally criticised, because it is presupposed by all rationality.
     From: J Baggini / PS Fosl (The Philosopher's Toolkit [2003], §1.12)
     A reaction: Nietzsche certainly wasn't afraid to ask why we should reject something because it is a contradiction. The 'logic of personal advantage' might allow logical contradictions.
2. Reason / C. Styles of Reason / 1. Dialectic
Dialectic aims at unified truth, unlike analysis, which divides into parts [Baggini /Fosl]
     Full Idea: Dialectic can be said to aim at wholeness or unity, while 'analytic' thinking divides that with which it deals into parts.
     From: J Baggini / PS Fosl (The Philosopher's Toolkit [2003], §2.03)
     A reaction: I don't accept this division (linked here to Hegel). I am a fan of analysis, as practised by Aristotle, but it is like dismantling an engine to identify and clean the parts, before reassembling it more efficiently.
4. Formal Logic / B. Propositional Logic PL / 2. Tools of Propositional Logic / e. Axioms of PL
'Natural' systems of deduction are based on normal rational practice, rather than on axioms [Baggini /Fosl]
     Full Idea: A 'natural' system of deduction does not posit any axioms, but looks instead for its formulae to the practices of ordinary rationality.
     From: J Baggini / PS Fosl (The Philosopher's Toolkit [2003], §1.09)
     A reaction: Presumably there is some middle ground, where we attempt to infer the axioms of normal practice, and then build a strict system on them. We must be allowed to criticise 'normal' rationality, I hope.
In ideal circumstances, an axiom should be such that no rational agent could possibly object to its use [Baggini /Fosl]
     Full Idea: In ideal circumstances, an axiom should be such that no rational agent could possibly object to its use.
     From: J Baggini / PS Fosl (The Philosopher's Toolkit [2003], §1.09)
     A reaction: Yes, but the trouble is that all our notions of 'rational' (giving reasons, being consistent) break down when we look at unsupported axioms. In what sense is something rational if it is self-evident?
4. Formal Logic / E. Nonclassical Logics / 5. Relevant Logic
A logic is 'relevant' if premise and conclusion are connected, and 'paraconsistent' allows contradictions [Priest,G, by Friend]
     Full Idea: Priest and Routley have developed paraconsistent relevant logic. 'Relevant' logics insist on there being some sort of connection between the premises and the conclusion of an argument. 'Paraconsistent' logics allow contradictions.
     From: report of Graham Priest (works [1998]) by Michčle Friend - Introducing the Philosophy of Mathematics 6.8
     A reaction: Relevance blocks the move of saying that a falsehood implies everything, which sounds good. The offer of paraconsistency is very wicked indeed, and they are very naughty boys for even suggesting it.
4. Formal Logic / E. Nonclassical Logics / 6. Free Logic
Free logic is one of the few first-order non-classical logics [Priest,G]
     Full Idea: Free logic is an unusual example of a non-classical logic which is first-order.
     From: Graham Priest (Intro to Non-Classical Logic (1st ed) [2001], Pref)
4. Formal Logic / F. Set Theory ST / 2. Mechanics of Set Theory / a. Symbols of ST
X1 x X2 x X3... x Xn indicates the 'cartesian product' of those sets [Priest,G]
     Full Idea: X1 x X2 x X3... x Xn indicates the 'cartesian product' of those sets, the set of all the n-tuples with its first member in X1, its second in X2, and so on.
     From: Graham Priest (Intro to Non-Classical Logic (1st ed) [2001], 0.1.0)
<a,b&62; is a set whose members occur in the order shown [Priest,G]
     Full Idea: <a,b> is a set whose members occur in the order shown; <x1,x2,x3, ..xn> is an 'n-tuple' ordered set.
     From: Graham Priest (Intro to Non-Classical Logic (1st ed) [2001], 0.1.10)
a ∈ X says a is an object in set X; a ∉ X says a is not in X [Priest,G]
     Full Idea: a ∈ X means that a is a member of the set X, that is, a is one of the objects in X. a ∉ X indicates that a is not in X.
     From: Graham Priest (Intro to Non-Classical Logic (1st ed) [2001], 0.1.2)
{x; A(x)} is a set of objects satisfying the condition A(x) [Priest,G]
     Full Idea: {x; A(x)} indicates a set of objects which satisfy the condition A(x).
     From: Graham Priest (Intro to Non-Classical Logic (1st ed) [2001], 0.1.2)
{a1, a2, ...an} indicates that a set comprising just those objects [Priest,G]
     Full Idea: {a1, a2, ...an} indicates that the set comprises of just those objects.
     From: Graham Priest (Intro to Non-Classical Logic (1st ed) [2001], 0.1.2)
Φ indicates the empty set, which has no members [Priest,G]
     Full Idea: Φ indicates the empty set, which has no members
     From: Graham Priest (Intro to Non-Classical Logic (1st ed) [2001], 0.1.4)
{a} is the 'singleton' set of a (not the object a itself) [Priest,G]
     Full Idea: {a} is the 'singleton' set of a, not to be confused with the object a itself.
     From: Graham Priest (Intro to Non-Classical Logic (1st ed) [2001], 0.1.4)
X⊂Y means set X is a 'proper subset' of set Y [Priest,G]
     Full Idea: X⊂Y means set X is a 'proper subset' of set Y (if and only if all of its members are members of Y, but some things in Y are not in X)
     From: Graham Priest (Intro to Non-Classical Logic (1st ed) [2001], 0.1.6)
X⊆Y means set X is a 'subset' of set Y [Priest,G]
     Full Idea: X⊆Y means set X is a 'subset' of set Y (if and only if all of its members are members of Y).
     From: Graham Priest (Intro to Non-Classical Logic (1st ed) [2001], 0.1.6)
X = Y means the set X equals the set Y [Priest,G]
     Full Idea: X = Y means the set X equals the set Y, which means they have the same members (i.e. X⊆Y and Y⊆X).
     From: Graham Priest (Intro to Non-Classical Logic (1st ed) [2001], 0.1.6)
X ∩ Y indicates the 'intersection' of sets X and Y, the objects which are in both sets [Priest,G]
     Full Idea: X ∩ Y indicates the 'intersection' of sets X and Y, which is a set containing just those things that are in both X and Y.
     From: Graham Priest (Intro to Non-Classical Logic (1st ed) [2001], 0.1.8)
X∪Y indicates the 'union' of all the things in sets X and Y [Priest,G]
     Full Idea: X ∪ Y indicates the 'union' of sets X and Y, which is a set containing just those things that are in X or Y (or both).
     From: Graham Priest (Intro to Non-Classical Logic (1st ed) [2001], 0.1.8)
Y - X is the 'relative complement' of X with respect to Y; the things in Y that are not in X [Priest,G]
     Full Idea: Y - X indicates the 'relative complement' of X with respect to Y, that is, all the things in Y that are not in X.
     From: Graham Priest (Intro to Non-Classical Logic (1st ed) [2001], 0.1.8)
4. Formal Logic / F. Set Theory ST / 2. Mechanics of Set Theory / b. Terminology of ST
The 'relative complement' is things in the second set not in the first [Priest,G]
     Full Idea: The 'relative complement' of one set with respect to another is the things in the second set that aren't in the first.
     From: Graham Priest (Intro to Non-Classical Logic (1st ed) [2001], 0.1.8)
The 'intersection' of two sets is a set of the things that are in both sets [Priest,G]
     Full Idea: The 'intersection' of two sets is a set containing the things that are in both sets.
     From: Graham Priest (Intro to Non-Classical Logic (1st ed) [2001], 0.1.8)
The 'union' of two sets is a set containing all the things in either of the sets [Priest,G]
     Full Idea: The 'union' of two sets is a set containing all the things in either of the sets
     From: Graham Priest (Intro to Non-Classical Logic (1st ed) [2001], 0.1.8)
The 'induction clause' says complex formulas retain the properties of their basic formulas [Priest,G]
     Full Idea: The 'induction clause' says that whenever one constructs more complex formulas out of formulas that have the property P, the resulting formulas will also have that property.
     From: Graham Priest (Intro to Non-Classical Logic (1st ed) [2001], 0.2)
An 'ordered pair' (or ordered n-tuple) is a set with its members in a particular order [Priest,G]
     Full Idea: An 'ordered pair' (or ordered n-tuple) is a set with its members in a particular order.
     From: Graham Priest (Intro to Non-Classical Logic (1st ed) [2001], 0.1.10)
A 'cartesian product' of sets is the set of all the n-tuples with one member in each of the sets [Priest,G]
     Full Idea: A 'cartesian product' of sets is the set of all the n-tuples with one member in each of the sets.
     From: Graham Priest (Intro to Non-Classical Logic (1st ed) [2001], 0.1.10)
A 'set' is a collection of objects [Priest,G]
     Full Idea: A 'set' is a collection of objects.
     From: Graham Priest (Intro to Non-Classical Logic (1st ed) [2001], 0.1.2)
The 'empty set' or 'null set' has no members [Priest,G]
     Full Idea: The 'empty set' or 'null set' is a set with no members.
     From: Graham Priest (Intro to Non-Classical Logic (1st ed) [2001], 0.1.4)
A set is a 'subset' of another set if all of its members are in that set [Priest,G]
     Full Idea: A set is a 'subset' of another set if all of its members are in that set.
     From: Graham Priest (Intro to Non-Classical Logic (1st ed) [2001], 0.1.6)
A 'proper subset' is smaller than the containing set [Priest,G]
     Full Idea: A set is a 'proper subset' of another set if some things in the large set are not in the smaller set
     From: Graham Priest (Intro to Non-Classical Logic (1st ed) [2001], 0.1.6)
A 'singleton' is a set with only one member [Priest,G]
     Full Idea: A 'singleton' is a set with only one member.
     From: Graham Priest (Intro to Non-Classical Logic (1st ed) [2001], 0.1.4)
A 'member' of a set is one of the objects in the set [Priest,G]
     Full Idea: A 'member' of a set is one of the objects in the set.
     From: Graham Priest (Intro to Non-Classical Logic (1st ed) [2001], 0.1.2)
4. Formal Logic / F. Set Theory ST / 2. Mechanics of Set Theory / c. Basic theorems of ST
The empty set Φ is a subset of every set (including itself) [Priest,G]
     Full Idea: The empty set Φ is a subset of every set (including itself).
     From: Graham Priest (Intro to Non-Classical Logic (1st ed) [2001], 0.1.6)
5. Theory of Logic / D. Assumptions for Logic / 1. Bivalence
The principle of bivalence distorts reality, as when claiming that a person is or is not 'thin' [Baggini /Fosl]
     Full Idea: Forcing everything into the straightjacket of bivalence seriously distorts the world. The problem is most acute in the case of vague concepts, such as thinness. It is not straightforwardly true or false that a person is thin.
     From: J Baggini / PS Fosl (The Philosopher's Toolkit [2003], §3.03)
     A reaction: Can't argue with that. Can we divide all our concepts into either bivalent or vague? Presumably both propositions and concepts could be bivalent.
5. Theory of Logic / L. Paradox / 1. Paradox
Typically, paradoxes are dealt with by dividing them into two groups, but the division is wrong [Priest,G]
     Full Idea: A natural principle is the same kind of paradox will have the same kind of solution. Standardly Ramsey's first group are solved by denying the existence of some totality, and the second group are less clear. But denial of the groups sink both.
     From: Graham Priest (The Structure of Paradoxes of Self-Reference [1994], §5)
     A reaction: [compressed] This sums up the argument of Priest's paper, which is that it is Ramsey's division into two kinds (see Idea 13334) which is preventing us from getting to grips with the paradoxes. Priest, notoriously, just lives with them.
5. Theory of Logic / L. Paradox / 4. Paradoxes in Logic / b. König's paradox
The 'least indefinable ordinal' is defined by that very phrase [Priest,G]
     Full Idea: König: there are indefinable ordinals, and the least indefinable ordinal has just been defined in that very phrase. (Recall that something is definable iff there is a (non-indexical) noun-phrase that refers to it).
     From: Graham Priest (The Structure of Paradoxes of Self-Reference [1994], §3)
     A reaction: Priest makes great subsequent use of this one, but it feels like a card trick. 'Everything indefinable has now been defined' (by the subject of this sentence)? König, of course, does manage to pick out one particular object.
5. Theory of Logic / L. Paradox / 4. Paradoxes in Logic / c. Berry's paradox
'x is a natural number definable in less than 19 words' leads to contradiction [Priest,G]
     Full Idea: Berry: if we take 'x is a natural number definable in less than 19 words', we can generate a number which is and is not one of these numbers.
     From: Graham Priest (The Structure of Paradoxes of Self-Reference [1994], §3)
     A reaction: [not enough space to spell this one out in full]
5. Theory of Logic / L. Paradox / 4. Paradoxes in Logic / d. Richard's paradox
By diagonalization we can define a real number that isn't in the definable set of reals [Priest,G]
     Full Idea: Richard: φ(x) is 'x is a definable real number between 0 and 1' and ψ(x) is 'x is definable'. We can define a real by diagonalization so that it is not in x. It is and isn't in the set of reals.
     From: Graham Priest (The Structure of Paradoxes of Self-Reference [1994], §3)
     A reaction: [this isn't fully clear here because it is compressed]
5. Theory of Logic / L. Paradox / 5. Paradoxes in Set Theory / c. Burali-Forti's paradox
The least ordinal greater than the set of all ordinals is both one of them and not one of them [Priest,G]
     Full Idea: Burali-Forti: φ(x) is 'x is an ordinal', and so w is the set of all ordinals, On; δ(x) is the least ordinal greater than every member of x (abbreviation: log(x)). The contradiction is that log(On)∈On and log(On)∉On.
     From: Graham Priest (The Structure of Paradoxes of Self-Reference [1994], §2)
5. Theory of Logic / L. Paradox / 5. Paradoxes in Set Theory / e. Mirimanoff's paradox
The next set up in the hierarchy of sets seems to be both a member and not a member of it [Priest,G]
     Full Idea: Mirimanoff: φ(x) is 'x is well founded', so that w is the cumulative hierarchy of sets, V; &delta(x) is just the power set of x, P(x). If x⊆V, then V∈V and V∉V, since δ(V) is just V itself.
     From: Graham Priest (The Structure of Paradoxes of Self-Reference [1994], §2)
5. Theory of Logic / L. Paradox / 6. Paradoxes in Language / a. The Liar paradox
If you know that a sentence is not one of the known sentences, you know its truth [Priest,G]
     Full Idea: In the family of the Liar is the Knower Paradox, where φ(x) is 'x is known to be true', and there is a set of known things, Kn. By knowing a sentence is not in the known sentences, you know its truth.
     From: Graham Priest (The Structure of Paradoxes of Self-Reference [1994], §4)
     A reaction: [mostly my wording]
There are Liar Pairs, and Liar Chains, which fit the same pattern as the basic Liar [Priest,G]
     Full Idea: There are liar chains which fit the pattern of Transcendence and Closure, as can be seen with the simplest case of the Liar Pair.
     From: Graham Priest (The Structure of Paradoxes of Self-Reference [1994], §4)
     A reaction: [Priest gives full details] Priest's idea is that Closure is when a set is announced as complete, and Transcendence is when the set is forced to expand. He claims that the two keep coming into conflict.
7. Existence / C. Structure of Existence / 3. Levels of Reality
A necessary relation between fact-levels seems to be a further irreducible fact [Lynch/Glasgow]
     Full Idea: It seems unavoidable that the facts about logically necessary relations between levels of facts are themselves logically distinct further facts, irreducible to the microphysical facts.
     From: Lynch,MP/Glasgow,JM (The Impossibility of Superdupervenience [2003], C)
     A reaction: I'm beginning to think that rejecting every theory of reality that is proposed by carefully exposing some infinite regress hidden in it is a rather lazy way to do philosophy. Almost as bad as rejecting anything if it can't be defined.
7. Existence / C. Structure of Existence / 5. Supervenience / c. Significance of supervenience
If some facts 'logically supervene' on some others, they just redescribe them, adding nothing [Lynch/Glasgow]
     Full Idea: Logical supervenience, restricted to individuals, seems to imply strong reduction. It is said that where the B-facts logically supervene on the A-facts, the B-facts simply re-describe what the A-facts describe, and the B-facts come along 'for free'.
     From: Lynch,MP/Glasgow,JM (The Impossibility of Superdupervenience [2003], C)
     A reaction: This seems to be taking 'logically' to mean 'analytically'. Presumably an entailment is logically supervenient on its premisses, and may therefore be very revealing, even if some people think such things are analytic.
7. Existence / D. Theories of Reality / 6. Physicalism
Nonreductive materialism says upper 'levels' depend on lower, but don't 'reduce' [Lynch/Glasgow]
     Full Idea: The root intuition behind nonreductive materialism is that reality is composed of ontologically distinct layers or levels. …The upper levels depend on the physical without reducing to it.
     From: Lynch,MP/Glasgow,JM (The Impossibility of Superdupervenience [2003], B)
     A reaction: A nice clear statement of a view which I take to be false. This relationship is the sort of thing that drives people fishing for an account of it to use the word 'supervenience', which just says two things seem to hang out together. Fluffy materialism.
The hallmark of physicalism is that each causal power has a base causal power under it [Lynch/Glasgow]
     Full Idea: Jessica Wilson (1999) says what makes physicalist accounts different from emergentism etc. is that each individual causal power associated with a supervenient property is numerically identical with a causal power associated with its base property.
     From: Lynch,MP/Glasgow,JM (The Impossibility of Superdupervenience [2003], n 11)
     A reaction: Hence the key thought in so-called (serious, rather than self-evident) 'emergentism' is so-called 'downward causation', which I take to be an idle daydream.
9. Objects / F. Identity among Objects / 3. Relative Identity
If identity is based on 'true of X' instead of 'property of X' we get the Masked Man fallacy ('I know X but not Y') [Baggini /Fosl, by PG]
     Full Idea: The Masked Man fallacy is when Leibniz's Law is taken as 'X and Y are identical if what is true of X is true of Y' (rather than being about properties). Then 'I know X' but 'I don't know Y' (e.g. my friend wearing a mask) would make X and Y non-identical.
     From: report of J Baggini / PS Fosl (The Philosopher's Toolkit [2003], §3.17) by PG - Db (ideas)
     A reaction: As the book goes on to explain, Descartes is guilty of this when arguing that I necessarily know my mind but not my body, so they are different. Seems to me that Kripke falls into the same trap.
9. Objects / F. Identity among Objects / 4. Type Identity
'I have the same car as you' is fine; 'I have the same fiancée as you' is not so good [Baggini /Fosl]
     Full Idea: If you found that I had the same car as you, I don't suppose you would care, but if you found I had the same fiancée as you, you might not be so happy.
     From: J Baggini / PS Fosl (The Philosopher's Toolkit [2003], §4.17)
     A reaction: A very nice illustration of the ambiguity of "same", and hence of identity. 'I had the same thought as you'. 'I have the same DNA as you'.
9. Objects / F. Identity among Objects / 7. Indiscernible Objects
Leibniz's Law is about the properties of objects; the Identity of Indiscernibles is about perception of objects [Baggini /Fosl]
     Full Idea: Leibniz's Law ('if identical, must have same properties') defines identity according to the properties possessed by the object itself, but the Identity of Indiscernibles defines identity in terms of how things are conceived or grasped by the mind.
     From: J Baggini / PS Fosl (The Philosopher's Toolkit [2003], §3.16)
     A reaction: This is the heart of the problem of identity. We realists must fight for Leibniz's Law, and escort the Identity of Indiscernibles to the door.
10. Modality / A. Necessity / 3. Types of Necessity
Is 'events have causes' analytic a priori, synthetic a posteriori, or synthetic a priori? [Baggini /Fosl]
     Full Idea: Of the proposition that "all experienced events have causes", Descartes says this is analytic a priori, Hume says it is synthetic a posteriori, and Kant says it is synthetic a priori.
     From: J Baggini / PS Fosl (The Philosopher's Toolkit [2003], §4.01)
     A reaction: I am not sympathetic to Hume on this (though most people think he is right). I prefer the Kantian view, but he makes a very large claim. Something has to be intuitive.
12. Knowledge Sources / A. A Priori Knowledge / 1. Nature of the A Priori
'A priori' does not concern how you learn a proposition, but how you show whether it is true or false [Baggini /Fosl]
     Full Idea: What makes something a priori is not the means by which it came to be known, but the means by which it can be shown to be true or false.
     From: J Baggini / PS Fosl (The Philosopher's Toolkit [2003], §4.01)
     A reaction: Helpful. Kripke in particular has labelled the notion as an epistemological one, but that does imply a method of acquiring it. Clearly I can learn an a priori truth by reading it the newspaper.
13. Knowledge Criteria / B. Internal Justification / 4. Foundationalism / b. Basic beliefs
Basic beliefs are self-evident, or sensual, or intuitive, or revealed, or guaranteed [Baggini /Fosl]
     Full Idea: Sentence are held to be basic because they are self-evident or 'cataleptic' (Stoics), or rooted in sense data (positivists), or grasped by intuition (Platonists), or revealed by God, or grasped by faculties certified by God (Descartes).
     From: J Baggini / PS Fosl (The Philosopher's Toolkit [2003], §1.01)
     A reaction: These are a bit blurred. Isn't intuition self-evident? Isn't divine guarantee a type of revelation? How about reason, experience or authority?
14. Science / A. Basis of Science / 6. Falsification
A proposition such as 'some swans are purple' cannot be falsified, only verified [Baggini /Fosl]
     Full Idea: The problem with falsification is that it fails to work with logically particular claims such as 'some swans are purple'. Examining a million swans and finding no purple ones does not falsify the claim, as there might still be a purple swan out there.
     From: J Baggini / PS Fosl (The Philosopher's Toolkit [2003], §3.29)
     A reaction: Isn't it beautiful how unease about a theory (Popper's) slowly crystallises into an incredibly simple and devastating point? Maybe 'some swans are purple' isn't science unless there is a good reason to propose it?
14. Science / C. Induction / 1. Induction
The problem of induction is how to justify our belief in the uniformity of nature [Baggini /Fosl]
     Full Idea: At its simplest, the problem of induction can be boiled down to the problem of justifying our belief in the uniformity of nature.
     From: J Baggini / PS Fosl (The Philosopher's Toolkit [2003], §1.03)
     A reaction: An easy solution to the problem of induction: we treat the uniformity of nature as axiomatic, and then induction is all reasoning which is based on that axiom. The axiom is a working hypothesis, which may begin to appear false. Anomalies are hard.
14. Science / C. Induction / 4. Reason in Induction
How can an argument be good induction, but poor deduction? [Baggini /Fosl]
     Full Idea: The problem of induction is the problem of how an argument can be good reasoning as induction but poor reasoning as deduction.
     From: J Baggini / PS Fosl (The Philosopher's Toolkit [2003], §1.03)
     A reaction: Nicely put, and a good defence of Hume against the charge that he has just muddled induction and deduction. All reasoning, we insist, should be consistent, or it isn't reasoning.
14. Science / D. Explanation / 3. Best Explanation / a. Best explanation
Abduction aims at simplicity, testability, coherence and comprehensiveness [Baggini /Fosl]
     Full Idea: There are some 'principles of selection' in abduction: 1) prefer simple explanations, 2) prefer coherent explanations (consistent with what is already held true), 3) prefer theories that make testable predictions, and 4) be comprehensive in scope.
     From: J Baggini / PS Fosl (The Philosopher's Toolkit [2003], §2.01)
     A reaction: Note that these are desirable, but not necessary (pace Ockham and Ayer). I cannot think of anything to add to the list, so I will adopt it. Abduction is the key to rationality.
To see if an explanation is the best, it is necessary to investigate the alternative explanations [Baggini /Fosl]
     Full Idea: The only way to be sure we have the best explanation is to investigate the alternatives and see if they are any better.
     From: J Baggini / PS Fosl (The Philosopher's Toolkit [2003], §3.01)
     A reaction: Unavoidable! Since I love 'best explanation', I now seem to be committed to investigation every mad theory that comes up, just in case it is better. I hope I am allowed to reject after a very quick sniff.
18. Thought / A. Modes of Thought / 5. Rationality / a. Rationality
Consistency is the cornerstone of rationality [Baggini /Fosl]
     Full Idea: Consistency is the cornerstone of rationality.
     From: J Baggini / PS Fosl (The Philosopher's Toolkit [2003], §1.06)
     A reaction: This is right, and is a cornerstone of Kant's approach to ethics. Rational beings must follow principles - in order to be consistent in their behaviour. 'Consistent' now requires a definition….