19463
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Induction assumes some uniformity in nature, or that in some respects the future is like the past [Ayer]
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Full Idea:
In all inductive reasoning we make the assumption that there is a measure of uniformity in nature; or, roughly speaking, that the future will, in the appropriate respects, resemble the past.
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From:
A.J. Ayer (The Problem of Knowledge [1956], 2.viii)
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A reaction:
I would say that nature is 'stable'. Nature changes, so a global assumption of total uniformity is daft. Do we need some global uniformity assumptions, if the induction involved is local? I would say yes. Are all inductions conditional on this?
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4901
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Truth has to be correspondence to facts, and a match between relations of ideas and relations in the world [Perry]
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Full Idea:
I think knowledge and truth are a matter of correspondence to facts, despite all the energy spent showing the naïveté of this view. The connections of our ideas in our heads correspond to relations in the outside world.
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From:
John Perry (Knowledge, Possibility and Consciousness [2001], §8.1)
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A reaction:
Yes. Modern books offer the difficulties of defining 'correspondence', and finding an independent account of 'facts', as conclusive objections, but I say a brain is a truth machine, and it had better be useful. Indefinability doesn't nullify concepts.
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4885
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Identity is a very weak relation, which doesn't require interdefinability, or shared properties [Perry]
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Full Idea:
The truth of "a=b" doesn't require much of 'a' and 'b' other than that there is a single thing to which they both refer. They needn't be interdefinable, or have supervenient properties. In this sense, identity is a very weak relation.
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From:
John Perry (Knowledge, Possibility and Consciousness [2001], §1.2)
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A reaction:
Interesting. This is seeing the epistemological aspects of identity. Ontologically, identity must invoke Leibniz's Law, and is the ultimately powerful 'relation'. A given student, and the cause of a crop circle, may APPEAR to be quite different.
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4899
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Possible worlds thinking has clarified the logic of modality, but is problematic in epistemology [Perry]
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Full Idea:
Using possible worlds to model truth-conditions of statements has led to considerable clarity about the logic of modality. Attempts to use the system for epistemic purposes, however, have been plagued by problems.
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From:
John Perry (Knowledge, Possibility and Consciousness [2001], §8.1)
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A reaction:
Presumably what lurks behind this is a distinction between what is logically or naturally possible, and what appears to be possible from the perspective of a conscious mind. Is there a possible world in which I can fly?
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4898
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Possible worlds are indices for a language, or concrete realities, or abstract possibilities [Perry]
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Full Idea:
Possible worlds can be thought of as indices for models of the language in question, or as concrete realities (David Lewis), or as abstract ways the world might be (Robert Stalnaker), or in various other ways.
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From:
John Perry (Knowledge, Possibility and Consciousness [2001], §8.1)
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A reaction:
I strongly favour the Stalnaker route here. Reducing great metaphysics to mere language I find abhorrent, and I suspect that Lewis was trapped by his commitment to strong empiricism. We must embrace abstractions into our ontology.
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19459
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To say 'I am not thinking' must be false, but it might have been true, so it isn't self-contradictory [Ayer]
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Full Idea:
To say 'I am not thinking' is self-stultifying since if it is said intelligently it must be false: but it is not self-contradictory. The proof that it is not self-contradictory is that it might have been false.
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From:
A.J. Ayer (The Problem of Knowledge [1956], 2.iii)
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A reaction:
If it doesn't imply a contradiction, then it is not a necessary truth, which is what it is normally taken to be. Is 'This is a sentence' necessarily true? It might not have been one, if the rules of English syntax changed recently.
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19460
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'I know I exist' has no counterevidence, so it may be meaningless [Ayer]
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Full Idea:
If there is no experience at all of finding out that one is not conscious, or that one does not exist, ..it is tempting to say that sentences like 'I exist', 'I am conscious', 'I know that I exist' do not express genuine propositions.
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From:
A.J. Ayer (The Problem of Knowledge [1956], 2.iii)
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A reaction:
This is, of course, an application of the somewhat discredited verification principle, but the fact that strictly speaking the principle has been sort of refuted does not mean that we should not take it seriously, and be influenced by it.
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19462
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Induction passes from particular facts to other particulars, or to general laws, non-deductively [Ayer]
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Full Idea:
Inductive reasoning covers all cases in which we pass from a particular statement of fact, or set of them, to a factual conclusion which they do not formally entail. The inference may be to a general law, or by analogy to another particular instance.
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From:
A.J. Ayer (The Problem of Knowledge [1956], 2.viii)
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A reaction:
My preferred definition is 'learning from experience' - which I take to be the most rational behaviour you could possibly imagine. I don't think a definition should be couched in terms of 'objects' or 'particulars'.
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4891
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If epiphenomenalism just says mental events are effects but not causes, it is consistent with physicalism [Perry]
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Full Idea:
Epiphenomenalism is usually considered to be a form of dualism, but if we define it as the doctrine that conscious events are effects but not causes, it appears to be consistent with physicalism.
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From:
John Perry (Knowledge, Possibility and Consciousness [2001], §4.2)
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A reaction:
Interesting. The theory was invented to put mind outside physics, and make the closure of physics possible. However, being capable of causing things seems to be a necessary condition for physical objects. An effect in one domain is a cause in another.
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4889
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Although we may classify ideas by content, we individuate them differently, as their content can change [Perry]
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Full Idea:
Although we classify ideas by content for many purposes, we do not individuate them by content. The content of an idea can change.
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From:
John Perry (Knowledge, Possibility and Consciousness [2001], §3.2)
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A reaction:
As the compiler of this database, I find this very appealing. The mind works exactly like a database. I have a 'file' (Perry's word) marked "London", the content of which undergoes continual change. I am a database management system.
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4896
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The intension of an expression is a function from possible worlds to an appropriate extension [Perry]
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Full Idea:
In possible-worlds semantics, expressions have intensions, which are functions from possible worlds to appropriate extensions (names to individuals, n-place predicates to n-tuples, and sentences to truth values, built from parts).
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From:
John Perry (Knowledge, Possibility and Consciousness [2001], §8.1)
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A reaction:
Interesting. Perry distinguishes 'referential' (or 'subject matter') content, which is prior to the link to extensions - a link which creates 'reflexive' content. He is keen that they should not become confused. True knowledge is 'situated'.
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