13 ideas
14970 | Normal system K has five axioms and rules [Cresswell] |
Full Idea: Normal propositional modal logics derive from the minimal system K: wffs of PC are axioms; □(p⊃q)⊃(□p⊃□q); uniform substitution; modus ponens; necessitation (α→□α). | |
From: Max J. Cresswell (Modal Logic [2001], 7.1) |
14971 | D is valid on every serial frame, but not where there are dead ends [Cresswell] |
Full Idea: If a frame contains any dead end or blind world, then D is not valid on that frame, ...but D is valid on every serial frame. | |
From: Max J. Cresswell (Modal Logic [2001], 7.1.1) |
14972 | S4 has 14 modalities, and always reduces to a maximum of three modal operators [Cresswell] |
Full Idea: In S4 there are exactly 14 distinct modalities, and any modality may be reduced to one containing no more than three modal operators in sequence. | |
From: Max J. Cresswell (Modal Logic [2001], 7.1.2) | |
A reaction: The significance of this may be unclear, but it illustrates one of the rewards of using formal systems to think about modal problems. There is at least an appearance of precision, even if it is only conditional precision. |
14973 | In S5 all the long complex modalities reduce to just three, and their negations [Cresswell] |
Full Idea: S5 contains the four main reduction laws, so the first of any pair of operators may be deleted. Hence all but the last modal operator may be deleted. This leaves six modalities: p, ◊p, □p, and their negations. | |
From: Max J. Cresswell (Modal Logic [2001], 7.1.2) |
14976 | Reject the Barcan if quantifiers are confined to worlds, and different things exist in other worlds [Cresswell] |
Full Idea: If one wants the quantifiers in each world to range only over the things that exist in that world, and one doesn't believe that the same things exist in every world, one would probably not want the Barcan formula. | |
From: Max J. Cresswell (Modal Logic [2001], 7.2.2) | |
A reaction: I haven't quite got this, but it sounds to me like I should reject the Barcan formula (but Idea 9449!). I like a metaphysics to rest on the actual world (with modal properties). I assume different things could have existed, but don't. |
14974 | A relation is 'Euclidean' if aRb and aRc imply bRc [Cresswell] |
Full Idea: A relation is 'Euclidean' if aRb and aRc imply bRc. | |
From: Max J. Cresswell (Modal Logic [2001], 7.1.2) | |
A reaction: If a thing has a relation to two separate things, then those two things will also have that relation between them. If I am in the same family as Jim and as Jill, then Jim and Jill are in the same family. |
14975 | A de dicto necessity is true in all worlds, but not necessarily of the same thing in each world [Cresswell] |
Full Idea: A de dicto necessary truth says that something is φ, that this proposition is a necessary truth, i.e. that in every accessible world something (but not necessarily the same thing in each world) is φ. | |
From: Max J. Cresswell (Modal Logic [2001], 7.2.1) | |
A reaction: At last, a really clear and illuminating account of this term! The question is then invited of what is the truthmaker for a de dicto truth, assuming that the objects themselves are truthmakers for de re truths. |
21862 | Consciousness is based on 'I can', not on 'I think' [Merleau-Ponty] |
Full Idea: Consciousness is in the first place not a matter of 'I think' but of 'I can'. | |
From: Maurice Merleau-Ponty (Phenomenology of Perception [1945], p.159), quoted by Beth Lord - Spinoza's Ethics 2 'Sensation' | |
A reaction: The point here (quoted during a discussion of Spinoza) is that you can't leave out the role of the body, which seems correct. |
20750 | The mind does not unite perceptions, because they flow into one another [Merleau-Ponty] |
Full Idea: I do not have one perception, then another, and between them a link brought about by the mind. Rather, each perspective merges into the other [against a unified background]. | |
From: Maurice Merleau-Ponty (Phenomenology of Perception [1945], p.329-30), quoted by Kevin Aho - Existentialism: an introduction 3 'Perceptual' | |
A reaction: I take this to be another piece of evidence pointing to realism as the best explanation of experience. A problem for Descartes is what unites the sequence of thoughts. |
3488 | Freud treats the unconscious as intentional and hence mental [Freud, by Searle] |
Full Idea: Freud thinks that our unconscious mental states exist as occurrent intrinsic intentional states even when unconscious. Their ontology is that of the mental, even when they are unconscious. | |
From: report of Sigmund Freud (works [1900]) by John Searle - The Rediscovery of the Mind Ch. 7.V | |
A reaction: Searle states this view in order to attack it. Whether such states are labelled as 'mental' seems uninteresting. Whether unconscious states can be intentional is crucial, and modern scientific understanding of the brain strongly suggest they can. |
5689 | Freud and others have shown that we don't know our own beliefs, feelings, motive and attitudes [Freud, by Shoemaker] |
Full Idea: Freud persuaded many that beliefs, wishes and feelings are sometimes unconscious, and even sceptics about Freud acknowledge that there is self-deception about motive and attitudes. | |
From: report of Sigmund Freud (works [1900]) by Sydney Shoemaker - Introspection p.396 | |
A reaction: This seems to me obviously correct. The traditional notion is that the consciousness is the mind, but now it seems obvious that consciousness is only one part of the mind, and maybe even a peripheral (epiphenomenal) part of it. |
23950 | Freud said passions are pressures of some flowing hydraulic quantity [Freud, by Solomon] |
Full Idea: Freud argued that the passions in general …were the pressures of a yet unknown 'quantity' (which he simply designated 'Q'). He first thought this flowed through neurones, …and always couched the idea in the language of hydraulics. | |
From: report of Sigmund Freud (works [1900]) by Robert C. Solomon - The Passions 3.4 | |
A reaction: This is the main target of Solomon's criticism, because its imagery has become so widespread. It leads to talk of suppressing emotions, or sublimating them. However, it is not too different from Nietzsche's 'drives' or 'will to power'. |
22344 | Freud is pessimistic about human nature; it is ambivalent motive and fantasy, rather than reason [Freud, by Murdoch] |
Full Idea: Freud takes a thoroughly pessimistic view of human nature. ...Introspection reveals only the deep tissue of ambivalent motive, and fantasy is a stronger force than reason. Objectivity and unselfishness are not natural to human beings. | |
From: report of Sigmund Freud (works [1900], II) by Iris Murdoch - The Sovereignty of Good II | |
A reaction: Interesting. His view seems to have coloured the whole of modern culture, reinforced by the hideous irrationality of the Nazis. Adorno and Horkheimer attacking the Enlightenment was the last step in that process. |