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18073
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Dummett says classical logic rests on meaning as truth, while intuitionist logic rests on assertability [Dummett, by Kitcher]
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Full Idea:
Dummett argues that classical logic depends on the choice of the concept of truth as central to the theory of meaning, while for the intuitionist the concept of assertability occupies this position.
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From:
report of Michael Dummett (The philosophical basis of intuitionist logic [1973]) by Philip Kitcher - The Nature of Mathematical Knowledge 06.5
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A reaction:
Since I can assert any nonsense I choose, this presumably means 'warranted' assertability, which is tied to the concept of proof in mathematics. You can reason about falsehoods, or about uninterpreted variables. Can you 'assert' 'Fx'?
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7401
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Heat and colour don't exist, so cannot mislead about the external world [Galileo, by Tuck]
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Full Idea:
Galileo argued that there is no such thing as heat (and hence also as colour) in the external world, so there is no reason to conclude from colour-blindness that we cannot know the truth about the world.
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From:
report of Galileo Galilei (Il Saggiatore ('The Assayer') [1623]) by Richard Tuck - Hobbes Ch.1
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A reaction:
This key idea, taken up by Gassendi, Descartes and Locke, seems to me to be one of the most important (and, in retrospect, rather obvious) facts ever worked out by the human mind. Why does anyone still doubt it?
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5454
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Tastes, odours and colours only reside in consciousness, and would disappear with creatures [Galileo]
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Full Idea:
I think tastes, odours, colours, and so on are mere names as far as the objects are concerned, and only reside in consciousness. Hence if the living creature were removed, all these qualities would be wiped away and annihilated.
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From:
Galileo Galilei (Il Saggiatore ('The Assayer') [1623]), quoted by Brian Ellis - The Philosophy of Nature: new essentialism Ch.3
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A reaction:
A nice bold assertion of the primary/secondary distinction from the first great scientist. I agree, and to disagree (and hence side with Berkeley and Hume) is to head for metaphsical and epistemological confusion.
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16560
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Galileo introduced geometrico-mechanical explanation, based on Archimedes [Galileo, by Machamer/Darden/Craver]
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Full Idea:
The modern idea of explaining with mechanisms became current in the 17th century when Galileo articulated a geometrico-mechanical form of explanation based on Archimedes' simple machines. This became the 'mechanical philosophy'.
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From:
report of Galileo Galilei (Il Saggiatore ('The Assayer') [1623]) by Machamer,P/Darden,L/Craver,C - Thinking About Mechanisms 5.2
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A reaction:
So is Archimedes the source? I would say that mechanical explanation is just commonsense, and is predominant in all human thinking, even in tiny infants.
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19056
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If a sentence is effectively undecidable, we can never know its truth conditions [Dummett]
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Full Idea:
If a sentence is effectively undecidable, the condition which must obtain for it to be true is not one which we are capable of recognising whenever it obtains, or of getting ourselves in a position to do so.
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From:
Michael Dummett (The philosophical basis of intuitionist logic [1973], p.225)
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A reaction:
The instances of 'undecidable' sentences are most clearly seen in mathematics, such as the Continuum Hypothesis or Goldbach's Conjecture, or anything involving vast infinite cardinals. But do you need precise truth-conditions for meaning?
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6616
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Least action is not a causal law, but a 'global law', describing a global essence [Ellis]
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Full Idea:
The principle of least action is not a causal law, but is what I call a 'global law', which describes the essence of the global kind, which every object in the universe necessarily instantiates.
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From:
Brian Ellis (Katzav on limitations of dispositions [2005])
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A reaction:
As a fan of essentialism I find this persuasive. If I inherit part of my essence from being a mammal, I inherit other parts of my essence from being an object, and all objects would share that essence, so it would look like a 'law' for all objects.
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6615
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A species requires a genus, and its essence includes the essence of the genus [Ellis]
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Full Idea:
A specific universal can exist only if the generic universal of which it is a species exists, but generic universals don't depend on species; …the essence of any genus is included in its species, but not conversely.
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From:
Brian Ellis (Katzav on limitations of dispositions [2005], 91)
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A reaction:
Thus the species 'electron' would be part of the genus 'lepton', or 'human' part of 'mammal'. The point of all this is to show how individual items connect up with the rest of the universe, giving rise to universal laws, such as Least Action.
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6614
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A hierarchy of natural kinds is elaborate ontology, but needed to explain natural laws [Ellis]
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Full Idea:
The hierarchy of natural kinds proposed by essentialism may be more elaborate than is strictly required for purposes of ontology, but it is necessary to explain the necessity of the laws of nature, and the universal applicability of global principles.
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From:
Brian Ellis (Katzav on limitations of dispositions [2005], 91)
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A reaction:
I am all in favour of elaborating ontology in the name of best explanation. There seem, though, to be some remaining ontological questions at the point where the explanations of essentialism run out.
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6612
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Without general principles, we couldn't predict the behaviour of dispositional properties [Ellis]
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Full Idea:
It is objected to dispositionalism that without the principle of least action, or some general principle of equal power, the specific dispositional properties of things could tell us very little about how these things would be disposed to behave.
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From:
Brian Ellis (Katzav on limitations of dispositions [2005], 90)
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A reaction:
Ellis attempts to meet this criticism, by placing dispositional properties within a hierarchy of broader properties. There remains a nagging doubt about how essentialism can account for space, time, order, and the existence of essences.
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