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All the ideas for 'The Case for Closure', 'Reflections on Knowledge, Truth and Ideas' and 'The Logic of Boundaryless Concepts'

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10 ideas

2. Reason / D. Definition / 1. Definitions

19426	'Nominal' definitions just list distinguishing characteristics [Leibniz]
	Full Idea: A 'nominal' definition is nothing more than an enumeration of the sufficient distinguishing characteristics.
	From: Gottfried Leibniz (Reflections on Knowledge, Truth and Ideas [1684], p.284)
	A reaction: Not wholly clear. Are these actual distinguishing characteristics, or potential ones? Could DNA be part of a human's nominal definition (for an unidentified corpse, perhaps).

5. Theory of Logic / A. Overview of Logic / 3. Value of Logic

9390	Logic guides thinking, but it isn't a substitute for it [Rumfitt]
	Full Idea: Logic is part of a normative theory of thinking, not a substitute for thinking.
	From: Ian Rumfitt (The Logic of Boundaryless Concepts [2007], p.13)
	A reaction: There is some sort of logicians' dream, going back to Leibniz, of a reasoning engine, which accepts propositions and outputs inferences. I agree with this idea. People who excel at logic are often, it seems to me, modest at philosophy.

9. Objects / B. Unity of Objects / 3. Unity Problems / e. Vague objects

9389	Vague membership of sets is possible if the set is defined by its concept, not its members [Rumfitt]
	Full Idea: Vagueness in respect of membership is consistency with determinacy of the set's identity, so long as a set's identity is taken to consist, not in its having such-and-such members, but in its being the extension of a concept.
	From: Ian Rumfitt (The Logic of Boundaryless Concepts [2007], p.5)
	A reaction: I find this view of sets much more appealing than the one that identifies a set with its members. The empty set is less of a problem, as well as non-existents. Logicians prefer the extensional view because it is tidy.

11. Knowledge Aims / A. Knowledge / 1. Knowledge

19424	Knowledge needs clarity, distinctness, and adequacy, and it should be intuitive [Leibniz]
	Full Idea: Knowledge is either obscure or clear; clear ideas are either indistinct or distinct; distinct ideas are either adequate or inadequate, symbolic or intuitive; perfect knowledge is that which is both adequate and intuitive.
	From: Gottfried Leibniz (Reflections on Knowledge, Truth and Ideas [1684], p.283)
	A reaction: This is Leibniz's expansion of Descartes's idea that knowledge rests on 'clear and distinct conceptions'. The ultimate target seems to be close to an Aristotelian 'real definition', which is comprehensive and precise. Does 'intuitive' mean coherent?

11. Knowledge Aims / B. Certain Knowledge / 2. Common Sense Certainty

19553	Commitment to 'I have a hand' only makes sense in a context where it has been doubted [Hawthorne]
	Full Idea: If I utter 'I know I have a hand' then I can only be reckoned a cooperative conversant by my interlocutors on the assumption that there was a real question as to whether I have a hand.
	From: John Hawthorne (The Case for Closure [2005], 2)
	A reaction: This seems to point to the contextualist approach to global scepticism, which concerns whether we are setting the bar high or low for 'knowledge'.

13. Knowledge Criteria / A. Justification Problems / 2. Justification Challenges / c. Knowledge closure

19551	How can we know the heavyweight implications of normal knowledge? Must we distort 'knowledge'? [Hawthorne]
	Full Idea: Those who deny skepticism but accept closure will have to explain how we know the various 'heavyweight' skeptical hypotheses to be false. Do we then twist the concept of knowledge to fit the twin desiderata of closue and anti-skepticism?
	From: John Hawthorne (The Case for Closure [2005], Intro)
	A reaction: [He is giving Dretske's view; Dretske says we do twist knowledge] Thus if I remember yesterday, that has the heavyweight implication that the past is real. Hawthorne nicely summarises why closure produces a philosophical problem.

19552	We wouldn't know the logical implications of our knowledge if small risks added up to big risks [Hawthorne]
	Full Idea: Maybe one cannot know the logical consequences of the proposition that one knows, on account of the fact that small risks add up to big risks.
	From: John Hawthorne (The Case for Closure [2005], 1)
	A reaction: The idea of closure is that the new knowledge has the certainty of logic, and each step is accepted. An array of receding propositions can lose reliability, but that shouldn't apply to logic implications. Assuming monotonic logic, of course.

19554	Denying closure is denying we know P when we know P and Q, which is absurd in simple cases [Hawthorne]
	Full Idea: How could we know that P and Q but not be in a position to know that P (as deniers of closure must say)? If my glass is full of wine, we know 'g is full of wine, and not full of non-wine'. How can we deny that we know it is not full of non-wine?
	From: John Hawthorne (The Case for Closure [2005], 2)
	A reaction: Hawthorne merely raises this doubt. Dretske is concerned with heavyweight implications, but how do you accept lightweight implications like this one, and then suddenly reject them when they become too heavy? [see p.49]

18. Thought / C. Content / 2. Ideas

19427	True ideas represent what is possible; false ideas represent contradictions [Leibniz]
	Full Idea: An idea is true if what it represents is possible; false if the representation contains a contradiction.
	From: Gottfried Leibniz (Reflections on Knowledge, Truth and Ideas [1684], p.287)
	A reaction: Odd in the analytic tradition to talk of a single idea or concept (rather than a proposition or utterance) as being 'true'. But there is clearly a notion of valid or legitimate or useful concepts here. Hilbert said true just meant non-contradictory.

26. Natural Theory / C. Causation / 2. Types of cause

19425	In the schools the Four Causes are just lumped together in a very obscure way [Leibniz]
	Full Idea: In the schools the four causes are lumped together as material, formal, efficient, and final causes, but they have no clear definitions, and I would call such a judgment 'obscure'.
	From: Gottfried Leibniz (Reflections on Knowledge, Truth and Ideas [1684], p.283)
	A reaction: He picks this to illustrate what he means by 'obscure', so he must feel strongly about it. Elsewhere Leibniz embraces efficient and final causes, but says little of the other two. This immediately become clearer as the Four Modes of Explanation.