14 ideas
| 8797 | The negation of all my beliefs about my current headache would be fully coherent [Sosa] |
| Full Idea: If I have a headache, I could have a set of beliefs that I do not have a headache, that I am not in pain, that no one is in pain, and so on. The resulting system of beliefs would cohere as fully as does my actual system of beliefs. | |
| From: Ernest Sosa (The Raft and the Pyramid [1980], §9) | |
| A reaction: I think this is a misunderstanding of coherentism. Beliefs are not to be formulated through a process of coherence, but are evaluated that way. A belief that I have headache just arrives; I then see that its denial is incoherent, so I accept it. |
| 10153 | In everyday language, truth seems indefinable, inconsistent, and illogical [Tarski] |
| Full Idea: In everyday language it seems impossible to define the notion of truth or even to use this notion in a consistent manner and in agreement with the laws of logic. | |
| From: Alfred Tarski (works [1936]), quoted by Feferman / Feferman - Alfred Tarski: life and logic Int III | |
| A reaction: [1935] See Logic|Theory of Logic|Semantics of Logic for Tarski's approach to truth. |
| 19141 | Tarski thought axiomatic truth was too contingent, and in danger of inconsistencies [Tarski, by Davidson] |
| Full Idea: Tarski preferred an explicit definition of truth to axioms. He says axioms have a rather accidental character, only a definition can guarantee the continued consistency of the system, and it keeps truth in harmony with physical science and physicalism. | |
| From: report of Alfred Tarski (works [1936]) by Donald Davidson - Truth and Predication 2 n2 | |
| A reaction: Davidson's summary, gleaned from various sources in Tarski. A big challenge for modern axiom systems is to avoid inconsistency, which is extremely hard to do (given that set theory is not sure of having achieved it). |
| 10048 | There is no clear boundary between the logical and the non-logical [Tarski] |
| Full Idea: No objective grounds are known to me which permit us to draw a sharp boundary between the two groups of terms, the logical and the non-logical. | |
| From: Alfred Tarski (works [1936]), quoted by Alan Musgrave - Logicism Revisited §3 | |
| A reaction: Musgrave is pointing out that this is bad news if you want to 'reduce' something like arithmetic to logic. 'Logic' is a vague object. |
| 10694 | Logical consequence is when in any model in which the premises are true, the conclusion is true [Tarski, by Beall/Restall] |
| Full Idea: Tarski's 1936 definition of logical consequence is that in any model in which the premises are true, the conclusion is true too (so that no model can make the conclusion false). | |
| From: report of Alfred Tarski (works [1936]) by JC Beall / G Restall - Logical Consequence 3 | |
| A reaction: So the general idea is that a logical consequence is distinguished by being unstoppable. Sounds good. But then we have monotonic and non-monotonic logics, which (I'm guessing) embody different notions of consequence. |
| 10479 | Logical consequence: true premises give true conclusions under all interpretations [Tarski, by Hodges,W] |
| Full Idea: Tarski's definition of logical consequence (1936) is that in a fully interpreted formal language an argument is valid iff under any allowed interpretation of its nonlogical symbols, if the premises are true then so is the conclusion. | |
| From: report of Alfred Tarski (works [1936]) by Wilfrid Hodges - Model Theory 3 | |
| A reaction: The idea that you can only make these claims 'under an interpretation' seems to have had a huge influence on later philosophical thinking. |
| 10157 | Tarski improved Hilbert's geometry axioms, and without set-theory [Tarski, by Feferman/Feferman] |
| Full Idea: Tarski found an elegant new axiom system for Euclidean geometry that improved Hilbert's earlier version - and he formulated it without the use of set-theoretical notions. | |
| From: report of Alfred Tarski (works [1936]) by Feferman / Feferman - Alfred Tarski: life and logic Ch.9 |
| 8794 | There are very few really obvious truths, and not much can be proved from them [Sosa] |
| Full Idea: Radical foundationalism suffers from two weaknesses: there are not so many perfectly obvious truths as Descartes thought; and if we restrict ourselves to what it truly obvious, very little supposed common sense knowledge can be proved. | |
| From: Ernest Sosa (The Raft and the Pyramid [1980], §3) | |
| A reaction: It is striking how few examples can ever be found of self-evident a priori truths. However, if there are self-evident truths about direct experience (pace Descartes), that would give us more than enough. |
| 8796 | A single belief can trail two regresses, one terminating and one not [Sosa] |
| Full Idea: A single belief can trail at once regresses of both sorts: one terminating and one not. | |
| From: Ernest Sosa (The Raft and the Pyramid [1980], §6) | |
| A reaction: This makes foundationalism possible, while admitting the existence of regresses. It is a good point, and triumphalist anti-foundationalists can't just point out a regress and then smugly troop off to the pub. |
| 8799 | If mental states are not propositional, they are logically dumb, and cannot be foundations [Sosa] |
| Full Idea: If a mental state is not propositional, then how can it possibly serve as a foundation for belief? How can one infer or justify anything on the basis of a state that, having no propositional content, must be logically dumb? | |
| From: Ernest Sosa (The Raft and the Pyramid [1980], §11) | |
| A reaction: This may be the best objection to foundationalism. McDowell tries to argue that conceptual content is inherent in perception, thus giving the beginnings of inbuilt propositional content. But an organism awash with bare experiences knows nothing. |
| 8795 | Mental states cannot be foundational if they are not immune to error [Sosa] |
| Full Idea: If a mental state provides no guarantee against error, then it cannot serve as a foundation for knowledge. | |
| From: Ernest Sosa (The Raft and the Pyramid [1980], §4) | |
| A reaction: That assumes that knowledge entails certainty, which I am sure it should not. On a fallibilist account, a foundation could be incredibly secure, despite a barely imaginable scenario in which it turned out to be false. |
| 8798 | Vision causes and justifies beliefs; but to some extent the cause is the justification [Sosa] |
| Full Idea: Visual experience is recognized as both the cause and the justification of our visual beliefs. But these are not wholly independent. Presumably the justification that something is red derives partly from the fact that it originates in visual experience. | |
| From: Ernest Sosa (The Raft and the Pyramid [1980], §10) | |
| A reaction: Yes, but the fact that certain visual experiences originate in dreams is taken as grounds for denying their truth, not affirming it. So why do we distinguish them? I am thinking that only in the 'space of reasons' can a cause become a justification. |
| 1748 | Archelaus was the first person to say that the universe is boundless [Archelaus, by Diog. Laertius] |
| Full Idea: Archelaus was the first person to say that the universe is boundless. | |
| From: report of Archelaus (fragments/reports [c.450 BCE]) by Diogenes Laertius - Lives of Eminent Philosophers 02.Ar.3 |
| 5989 | Archelaus said life began in a primeval slime [Archelaus, by Schofield] |
| Full Idea: Archelaus wrote that life on Earth began in a primeval slime. | |
| From: report of Archelaus (fragments/reports [c.450 BCE]) by Malcolm Schofield - Archelaus | |
| A reaction: This sounds like a fairly clearcut assertion of the production of life by evolution. Darwin's contribution was to propose the mechanism for achieving it. We should honour the name of Archelaus for this idea. |