18739
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Three stages of philosophical logic: syntactic (1905-55), possible worlds (1963-85), widening (1990-) [Horsten/Pettigrew]
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Full Idea:
Three periods can be distinguished in philosophical logic: the syntactic stage, from Russell's definite descriptions to the 1950s, the dominance of possible world semantics from the 50s to 80s, and a current widening of the subject.
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From:
Horsten,L/Pettigrew,R (Mathematical Methods in Philosophy [2014], 1)
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A reaction:
[compressed] I've read elsewhere that the arrival of Tarski's account of truth in 1933, taking things beyond the syntactic, was also a landmark.
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18740
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If 'exist' doesn't express a property, we can hardly ask for its essence [Horsten/Pettigrew]
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Full Idea:
If there is indeed no property of existence that is expressed by the word 'exist', then it makes no sense to ask for its essence.
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From:
Horsten,L/Pettigrew,R (Mathematical Methods in Philosophy [2014], 2)
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A reaction:
As far as I can tell, this was exactly Aristotle's conclusion, so he skirted round the question of 'being qua being', and focused on the nature of objects instead. Grand continental talk of 'Being' doesn't sound very interesting.
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14664
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Necessary beings (numbers, properties, sets, propositions, states of affairs, God) exist in all possible worlds [Plantinga]
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Full Idea:
A 'necessary being' is one that exists in every possible world; and only some objects - numbers, properties, pure sets, propositions, states of affairs, God - have this distinction.
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From:
Alvin Plantinga (Actualism and Possible Worlds [1976], 2)
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A reaction:
This a very odd list, though it is fairly orthodox among philosophers trained in modern modal logic. At the very least it looks rather parochial to me.
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14666
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Socrates is a contingent being, but his essence is not; without Socrates, his essence is unexemplified [Plantinga]
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Full Idea:
Socrates is a contingent being; his essence, however, is not. Properties, like propositions and possible worlds, are necessary beings. If Socrates had not existed, his essence would have been unexemplified, but not non-existent.
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From:
Alvin Plantinga (Actualism and Possible Worlds [1976], 4)
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A reaction:
This is a distinctive Plantinga view, of which I can make little sense. I take it that Socrates used to have an essence. Being dead, the essence no longer exists, but when we talk about Socrates it is largely this essence to which we refer. OK?
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14662
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Possible worlds clarify possibility, propositions, properties, sets, counterfacts, time, determinism etc. [Plantinga]
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Full Idea:
The idea of possible worlds has delivered insights on logical possibility (de dicto and de re), propositions, properties and sets, counterfactuals, time and temporal relations, causal determinism, the ontological argument, and the problem of evil.
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From:
Alvin Plantinga (Actualism and Possible Worlds [1976], Intro)
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A reaction:
This date (1976) seems to be the high-water mark for enthusiasm about possible worlds. I suppose if we just stick to 'insights' rather than 'answers' then the big claim might still be acceptable. Which problems are created by possible worlds?
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16472
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Plantinga's actualism is nominal, because he fills actuality with possibilia [Stalnaker on Plantinga]
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Full Idea:
Plantinga's critics worry that the metaphysics is actualist in name only, since it is achieved only by populating the actual world with entities whose nature is explained in terms of merely possible things that would exemplify them if anything did.
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From:
comment on Alvin Plantinga (Actualism and Possible Worlds [1976]) by Robert C. Stalnaker - Mere Possibilities 4.4
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A reaction:
Plantinga seems a long way from the usual motivation for actualism, which is probably sceptical empiricism, and building a system on what is smack in front of you. Possibilities have to be true, though. That's why you need dispositions in actuality.
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21053
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The manifest will in the world of phenomena has to conform to the laws of nature [Kant]
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Full Idea:
Whatever conception of the freedom of the will one may form in terms of metaphysics, the will's manifestations in the world of phenomena, i.e. human actions, are determined in accordance with natural laws, as is every other natural event.
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From:
Immanuel Kant (Idea for a Universal History [1784], Intro)
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A reaction:
So free will either requires total substance dualism, or it is best described as transcendental fictionalism. This seems to imply the Leibnizian idea that metaphysics contains facts which having nothing to do with the physical world.
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16469
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Plantinga has domains of sets of essences, variables denoting essences, and predicates as functions [Plantinga, by Stalnaker]
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Full Idea:
The domains in Plantinga's interpretation of Kripke's semantics are sets of essences, and the values of variables are essences. The values of predicates have to be functions from possible worlds to essences.
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From:
report of Alvin Plantinga (Actualism and Possible Worlds [1976]) by Robert C. Stalnaker - Mere Possibilities 4.4
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A reaction:
I begin to think this is quite nice, as long as one doesn't take the commitment to the essences too seriously. For 'essence' read 'minimal identity'? But I take essences to be more than minimal, so use identities (which Kripke does?).
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16470
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Plantinga's essences have their own properties - so will have essences, giving a hierarchy [Stalnaker on Plantinga]
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Full Idea:
For Plantinga, essences are entities in their own right and will have properties different from what instantiates them. Hence he will need individual essences of individual essences, distinct from the essences. I see no way to avoid a hierarchy of them.
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From:
comment on Alvin Plantinga (Actualism and Possible Worlds [1976]) by Robert C. Stalnaker - Mere Possibilities 4.4
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A reaction:
This sounds devastating for Plantinga, but it is a challenge for traditional Aristotelians. Only a logician suffers from a hierarchy, but a scientist might have to live with an essence, which contains a super-essence.
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14663
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Are propositions and states of affairs two separate things, or only one? I incline to say one [Plantinga]
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Full Idea:
Are there two sorts of thing, propositions and states of affairs, or only one? I am inclined to the former view on the ground that propositions have a property, truth or falsehood, not had by states of affairs.
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From:
Alvin Plantinga (Actualism and Possible Worlds [1976], 1)
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A reaction:
Might a proposition be nothing more than an assertion that a state of affairs obtains? It would then pass his test. The idea that a proposition is a complex of facts in the external world ('Russellian' propositions?) quite baffles me.
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