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All the ideas for '', 'The Nature of Necessity' and 'Modal Realism at Work: Properties'

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8 ideas

5. Theory of Logic / A. Overview of Logic / 1. Overview of Logic

11211	If a sound conclusion comes from two errors that cancel out, the path of the argument must matter [Rumfitt]
	Full Idea: If a designated conclusion follows from the premisses, but the argument involves two howlers which cancel each other out, then the moral is that the path an argument takes from premisses to conclusion does matter to its logical evaluation.
	From: Ian Rumfitt ("Yes" and "No" [2000], II)
	A reaction: The drift of this is that our view of logic should be a little closer to the reasoning of ordinary language, and we should rely a little less on purely formal accounts.

5. Theory of Logic / E. Structures of Logic / 2. Logical Connectives / a. Logical connectives

11210	Standardly 'and' and 'but' are held to have the same sense by having the same truth table [Rumfitt]
	Full Idea: If 'and' and 'but' really are alike in sense, in what might that likeness consist? Some philosophers of classical logic will reply that they share a sense by virtue of sharing a truth table.
	From: Ian Rumfitt ("Yes" and "No" [2000])
	A reaction: This is the standard view which Rumfitt sets out to challenge.

11212	The sense of a connective comes from primitively obvious rules of inference [Rumfitt]
	Full Idea: A connective will possess the sense that it has by virtue of its competent users' finding certain rules of inference involving it to be primitively obvious.
	From: Ian Rumfitt ("Yes" and "No" [2000], III)
	A reaction: Rumfitt cites Peacocke as endorsing this view, which characterises the logical connectives by their rules of usage rather than by their pure semantic value.

8. Modes of Existence / B. Properties / 11. Properties as Sets

4038	Properties are sets of their possible instances (which separates 'renate' from 'cordate') [Lewis, by Mellor/Oliver]
	Full Idea: Lewis agrees that properties cannot be sets of their actual instances, but claims they can be sets of their possible instances. This would distinguish coextensive properties like being cordate and renate, since they might be separated.
	From: report of David Lewis (Modal Realism at Work: Properties [1986]) by DH Mellor / A Oliver - Introduction to 'Properties' §10
	A reaction: Sounds wrong. Two properties could be obviously different even if they could never be separated. In this world a creature might briefly survive without kidneys.

10. Modality / E. Possible worlds / 1. Possible Worlds / d. Possible worlds actualism

18383	Plantinga says there is just this world, with possibilities expressed in propositions [Plantinga, by Armstrong]
	Full Idea: Plantinga rejects other possible worlds, but adds to our world an uncountable multitude of sets of propositions, each set a way that the world might have been, but is in fact not. (Roughly, for each Lewis world, Plantinga has such a set).
	From: report of Alvin Plantinga (The Nature of Necessity [1974]) by David M. Armstrong - Truth and Truthmakers 07.2
	A reaction: To me it seems as ontologically extravagant to postulate unexpressed propositions as to postulate concrete possible worlds. I think the best line is that there is just the actual world, with the possibilities implied in its dispositions.

10. Modality / E. Possible worlds / 3. Transworld Objects / b. Rigid designation

11891	Possibilities for an individual can only refer to that individual, in some possible world [Plantinga, by Mackie,P]
	Full Idea: Plantinga says for an individual to exist with certain properties in some possible world is simply for it to be true that, had that possible world obtained, that individual would have existed with those properties.
	From: report of Alvin Plantinga (The Nature of Necessity [1974]) by Penelope Mackie - How Things Might Have Been 5.1
	A reaction: This is intended to dissolve the problem of transworld identity, and is certainly a flat rejection of counterparts. I take the point to be that the individual is the key element in defining the possible world, so can't possibly be different.

19. Language / F. Communication / 3. Denial

11214	We learn 'not' along with affirmation, by learning to either affirm or deny a sentence [Rumfitt]
	Full Idea: The standard view is that affirming not-A is more complex than affirming the atomic sentence A itself, with the latter determining its sense. But we could learn 'not' directly, by learning at once how to either affirm A or reject A.
	From: Ian Rumfitt ("Yes" and "No" [2000], IV)
	A reaction: [compressed] This seems fairly anti-Fregean in spirit, because it looks at the psychology of how we learn 'not' as a way of clarifying what we mean by it, rather than just looking at its logical behaviour (and thus giving it a secondary role).

28. God / B. Proving God / 2. Proofs of Reason / a. Ontological Proof

20704	A possible world contains a being of maximal greatness - which is existence in all worlds [Plantinga, by Davies,B]
	Full Idea: Plantinga reformulates Malcolm's argument thus: 1) There is a possible world in which there exists a being with maximal greatness, 2) A being has maximal greatness in a world only if it exists in every world.
	From: report of Alvin Plantinga (The Nature of Necessity [1974], p.213) by Brian Davies - Introduction to the Philosophy of Religion 4 'b Descartes'
	A reaction: This is only Plantinga's starting point, which says nothing about the nature of God, but only that this 'great' being exists in all worlds. I would like to know why it is a 'being' rather than a 'thing'. Malcolm says if it is possible it is necessary.