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4739
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In "if and only if" (iff), "if" expresses the sufficient condition, and "only if" the necessary condition [Engel]
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Full Idea:
Necessary and sufficient conditions are usually expressed by "if and only if" (abbr. "iff"), where "if" is the sufficient condition, and "only if" is the necessary condition.
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From:
Pascal Engel (Truth [2002], §1.1)
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A reaction:
'I take my umbrella if and only if it is raining' (oh, and if I'm still alive). There may be other necessary conditions than the one specified. Oh, and I take it if my wife slips it into my car…
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4737
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Are truth-bearers propositions, or ideas/beliefs, or sentences/utterances? [Engel]
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Full Idea:
The tradition of the Stoics and Frege says that truth-bearers are propositions, Descartes and the classical empiricist say they are ideas or beliefs, and Ockham and Quine say they are sentences or utterances.
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From:
Pascal Engel (Truth [2002], §1.1)
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A reaction:
I'm with propositions, which are unambiguous, can be expressed in a variety of ways, embody the 'logical form' of sentences, and could be physically embodied in brains (the language of thought?).
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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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4763
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'Evidentialists' say, and 'voluntarists' deny, that we only believe on the basis of evidence [Engel]
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Full Idea:
The 'evidentialists' (such as Locke and Hume) deny, and the 'voluntarists' (such as William James) affirm, that we ought to, or at least may, believe for other reasons than evidential epistemic reasons (e.g. for pragmatic reasons).
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From:
Pascal Engel (Truth [2002], §5.2)
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A reaction:
No need to be black-or-white here. Blatant evidence compels belief, but we may also come to believe by spotting a coherence, without additional evidence. We can also be in a state of trying to believe something. But see 4764.
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4764
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We cannot directly control our beliefs, but we can control the causes of our involuntary beliefs [Engel]
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Full Idea:
Direct psychological voluntarism about beliefs seems to be false, but we can have an indirect voluntary control on many of our beliefs, by manipulating the states in us that are involuntary and which lead to certain beliefs.
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From:
Pascal Engel (Truth [2002], §5.2)
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A reaction:
Very nice! This points two ways - to scientific experiments, which can have compelling outcomes (see Fodor), and to brain-washing, and especially auto-brainwashing (only reading articles which support your favourites theories). What magazines do you take?
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18884
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Abstraction is usually seen as producing universals and numbers, but it can do more [Simons]
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Full Idea:
Abstraction as a cognitive tool has been associated predominantly with the metaphysics of universals and of mathematical objects such as numbers. But it is more widely applicable beyond this standard range. I commend its judicious use.
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From:
Peter Simons (Modes of Extension: comment on Fine [2008], p.21)
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A reaction:
Personally I think our view of the world is founded on three psychological principles: abstraction, idealisation and generalisation. You can try to give them rigour, as 'equivalence classes', or 'universal quantifications', if it makes you feel better.
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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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