26 ideas
| 19066 | Philosophy aims to understand the world, through ordinary experience and science [Dummett] |
| Full Idea: Philosophy is an attempt to understand the world, as it is revealed to us both in our ordinary experience and by the discoveries and theories of science. | |
| From: Michael Dummett (The Justification of Deduction [1973], p.311) | |
| A reaction: I don't see a sharp division between 'ordinary' and 'scientific'. I really like this idea, first because it makes 'understanding' central, and second because it wants both revelations. In discussing matter and time, there is too much emphasis on science. |
| 22024 | Fichte's subjectivity struggles to then give any account of objectivity [Pinkard on Fichte] |
| Full Idea: For Fichte 'subjectivity' came first, and he was then stuck with the (impossible) task of showing how 'objectivity' arose out of it. | |
| From: comment on Johann Fichte (The Science of Knowing (Wissenschaftslehre) [1st ed] [1794]) by Terry Pinkard - German Philosophy 1760-1860 06 | |
| A reaction: The best available answer to this problem (for idealists) is, I think, Nietzsche's perspectives, in which multiple subjectivities are summed to produce a blurred picture which has a degree of consensus. Fichte later embraced other minds. |
| 19067 | A successful proof requires recognition of truth at every step [Dummett] |
| Full Idea: For a demonstration to be cogent it is necessary that the passage from step to step involve a recognition of truth at each line. | |
| From: Michael Dummett (The Justification of Deduction [1973], p.313) | |
| A reaction: Dummett cited Quine (esp. 1970) as having an almost entirely syntactic view of logic. Rumfitt points out that logic can move validly from one falsehood to another. Even a 'proof' might detour into falsehood, but it would not be a 'canonical' proof! |
| 19060 | Truth-tables are dubious in some cases, and may be a bad way to explain connective meaning [Dummett] |
| Full Idea: It is arguable whether two-valued truth tables give correct meanings for certain sentential operators, and even whether they constitute legitimate explanations of any possible sentential operators. | |
| From: Michael Dummett (The Justification of Deduction [1973], p.294) | |
| A reaction: See 'Many-valued logic' for examples of non-binary truth tables. Presumably logicians should aspire to make their semantics precise, as well as their syntax. |
| 11066 | Deduction is justified by the semantics of its metalanguage [Dummett, by Hanna] |
| Full Idea: For Dummett the semantics of the metalanguage is the external and objective source of the justification of deduction. | |
| From: report of Michael Dummett (The Justification of Deduction [1973]) by Robert Hanna - Rationality and Logic 3.4 | |
| A reaction: This is offered as an answer to the Lewis Carroll problem that justifying deduction seems to need deduction, thus leading to a regress. [There is a reply to Dummett by Susan Haack] |
| 19058 | Syntactic consequence is positive, for validity; semantic version is negative, with counterexamples [Dummett] |
| Full Idea: A plausible account is that the syntactic notion of consequence is for positive results, that some form of argument is valid; the semantic notion is required for negative results, that some argument is invalid, because a counterexample can be found. | |
| From: Michael Dummett (The Justification of Deduction [1973], p.292) | |
| A reaction: This rings true for the two strategies of demonstration, the first by following the rules in steps, the second by using your imagination (or a tableau) to think up problems. |
| 22017 | Normativity needs the possibility of negation, in affirmation and denial [Fichte, by Pinkard] |
| Full Idea: To adopt any kind of normative stance is to commit oneself necessarily to the possibility of negation. It involves doing something correctly or incorrectly, so there must exist the possibility of denying or affirming. | |
| From: report of Johann Fichte (The Science of Knowing (Wissenschaftslehre) [1st ed] [1794]) by Terry Pinkard - German Philosophy 1760-1860 05 | |
| A reaction: This seems to be the key idea for understanding Hegel's logic. Personally I think animals have a non-verbal experience of negation - when a partner dies, for example. |
| 19063 | Beth trees show semantics for intuitionistic logic, in terms of how truth has been established [Dummett] |
| Full Idea: Beth trees give a semantics for intuitionistic logic, by representing sentence meaning in terms of conditions under which it is recognised to have been established as true. | |
| From: Michael Dummett (The Justification of Deduction [1973], p.305) |
| 19059 | In standard views you could replace 'true' and 'false' with mere 0 and 1 [Dummett] |
| Full Idea: Nothing is lost, on this view, if in the standard semantic treatment of classical sentential logic, we replace the standard truth-values 'true' and 'false' by the numbers 0 and 1. | |
| From: Michael Dummett (The Justification of Deduction [1973], p.294) | |
| A reaction: [A long context will explain 'on this view'] He is discussing the relationship of syntactic and semantic consequence, and goes on to criticise simple binary truth-table accounts of connectives. Semantics on a computer would just be 0 and 1. |
| 19062 | Classical two-valued semantics implies that meaning is grasped through truth-conditions [Dummett] |
| Full Idea: The standard two-valued semantics for classical logic involves a conception under which to grasp the meaning of a sentence is to apprehend the conditions under which it is, or is not, true. | |
| From: Michael Dummett (The Justification of Deduction [1973], p.305) | |
| A reaction: The idea is that you only have to grasp the truth tables for sentential logic, and that needs nothing more than knowing whether a sentence is true or false. I'm not sure where the 'conditions' creep in, though. |
| 19065 | Soundness and completeness proofs test the theory of meaning, rather than the logic theory [Dummett] |
| Full Idea: A proof of soundess or completeness is a test, not so much of the logical theory to which it applies, but of the theory of meaning which underlies the semantics. | |
| From: Michael Dummett (The Justification of Deduction [1973], p.310) | |
| A reaction: These two types of proof concern how the syntax and the semantics match up, so this claim sounds plausible, though I tend to think of them as more like roadworthiness tests for logic, checking how well they function. |
| 22018 | Necessary truths derive from basic assertion and negation [Fichte, by Pinkard] |
| Full Idea: Fichte thought that everything that involves necessary truths - even mathematics and logic - should be shown to follow from the more basic principles involved in assertion and negation. | |
| From: report of Johann Fichte (The Science of Knowing (Wissenschaftslehre) [1st ed] [1794]) by Terry Pinkard - German Philosophy 1760-1860 05 | |
| A reaction: An interesting proposal, though I am struggling to see how it works. Fichte sees assertion and negation as foundational (Idea 22017), but I take them to be responses to the real world. |
| 22064 | Fichte's logic is much too narrow, and doesn't deduce ethics, art, society or life [Schlegel,F on Fichte] |
| Full Idea: Only Fichte's principles are deduced in his book, that is, the logical ones, and not even these completely. And what about the practical, the moral and ethical ones. Society, learning, wit, art, and so on are also entitled to be deduced here. | |
| From: comment on Johann Fichte (The Science of Knowing (Wissenschaftslehre) [1st ed] [1794]) by Friedrich Schlegel - works Vol 18 p.34 | |
| A reaction: This is the beginnings of the romantic rebellion against a rather narrowly rationalist approach to philosophy. Schlegel also objects to the fact that Fichte only had one axiom (presumably the idea of the not-Self). |
| 22032 | Fichte's key claim was that the subjective-objective distinction must itself be subjective [Fichte, by Pinkard] |
| Full Idea: Fichte's key claim was that the difference between the subjective and the objective points of view had to be itself a subjective distinction, something that the 'I' posits. | |
| From: report of Johann Fichte (The Science of Knowing (Wissenschaftslehre) [1st ed] [1794]) by Terry Pinkard - German Philosophy 1760-1860 09 | |
| A reaction: This seems to lock us firmly into the idealist mental prison and throw away the key. |
| 19061 | An explanation is often a deduction, but that may well beg the question [Dummett] |
| Full Idea: An explanation is often a deductive argument, with the fact needing explaining as its conclusion. ...But the conclusion is usually given in advance, and we may only believe the premisses because they plausibly explain the conclusion. | |
| From: Michael Dummett (The Justification of Deduction [1973], p.296) | |
| A reaction: [compressed (Dummett's wordy prose cries out for it!)] I suppose this works better in mathematics, which is central to Dummett's interests. In the real world the puzzle is not usually logically implied by its explanation. |
| 22020 | We only see ourselves as self-conscious and rational in relation to other rationalities [Fichte] |
| Full Idea: A rational creature cannot posit itself as such a creature with self-consciousness without positing itself as an individual, as one among many rational creatures. | |
| From: Johann Fichte (The Science of Knowing (Wissenschaftslehre) [1st ed] [1794], p.8), quoted by Terry Pinkard - German Philosophy 1760-1860 05 n25 | |
| A reaction: [1796 book about his Wissenschaftlehre] This is the transcendental (Kantian) approach to other minds. Wittgenstein's private language argument is similar. Hegel was impressed by this idea (I think). |
| 22060 | The Self is the spontaneity, self-relatedness and unity needed for knowledge [Fichte, by Siep] |
| Full Idea: According to Fichte, spontaneity, self-relatedness, and unity are the basic traits of knowledge (which includes conscience). ...This principle of all knowledge is what he calls the 'I' or the Self. | |
| From: report of Johann Fichte (The Science of Knowing (Wissenschaftslehre) [1st ed] [1794]) by Ludwig Siep - Fichte p.58 | |
| A reaction: This is the idealist view. He gets 'spontaneity' from Kant, which is the mind's contribution to experience. Self-relatedness is the distinctive Fichte idea. Unity presumably means total coherence, which is typical of idealists. |
| 22066 | Novalis sought a much wider concept of the ego than Fichte's proposal [Novalis on Fichte] |
| Full Idea: Novalis aimed to create a theory of the ego with a much wider scope than Fichte's doctrine of knowledge had been able to establish. ....Without philosophy, imperfect poet - without poetry, imperfect thinker. | |
| From: comment on Johann Fichte (The Science of Knowing (Wissenschaftslehre) [1st ed] [1794]) by Novalis - Logological Fragments I vol.3 p.531 | |
| A reaction: [in his 'Fichte Studies] Since this is at the heart of early romanticism, I take the concept to embrace nature, as well as creative imagination. There is a general rebellion against the narrowness of Fichte. |
| 22016 | The self is not a 'thing', but what emerges from an assertion of normativity [Fichte, by Pinkard] |
| Full Idea: Fichte said the self is not a natural 'thing' but is itself a normative status, and 'it' can obtain this status, so it seems, only by an act of attributing it to itself. ...He continually identified the 'I' with 'reason' itself. | |
| From: report of Johann Fichte (The Science of Knowing (Wissenschaftslehre) [1st ed] [1794]) by Terry Pinkard - German Philosophy 1760-1860 05 | |
| A reaction: Pinkard says Fichte gradually qualified this claim. Fichte struggled to state his view in a way that avoided obvious paradoxes. 'My mind produces decisions, so there must be someone in charge of them'? Is this transcendental? |
| 22019 | Consciousness of an object always entails awareness of the self [Fichte] |
| Full Idea: I can be conscious of any object only on the condition that I am also conscious of myself, that is, of the conscious subject. This proposition is incontrovertible. | |
| From: Johann Fichte (The Science of Knowing (Wissenschaftslehre) [1st ed] [1794], p.112), quoted by Terry Pinkard - German Philosophy 1760-1860 05 | |
| A reaction: [from the 1797/8 version of Wissenschaftslehre] Russell might be cross to find that his idea on this was anticipated by Fichte. I still approve of the idea. |
| 22061 | Judgement is distinguishing concepts, and seeing their relations [Fichte, by Siep] |
| Full Idea: For Fichte, to judge means to distinguish concepts from one another and to place them in relationship to one another. | |
| From: report of Johann Fichte (The Science of Knowing (Wissenschaftslehre) [1st ed] [1794]) by Ludwig Siep - Fichte p.59 | |
| A reaction: This idea of Fichte's seems to be the key one for Hegel, and hence (I presume) it is the lynchpin of German Idealism. It seems to describe mathematical knowledge quite well. I don't think it fits judging whether there is a snake in the grass. |
| 19064 | Holism is not a theory of meaning; it is the denial that a theory of meaning is possible [Dummett] |
| Full Idea: In the sense of giving a model for the content of a sentence, its representative power, holism is not a theory of meaning; it is the denial that a theory of meaning is possible. | |
| From: Michael Dummett (The Justification of Deduction [1973], p.309) | |
| A reaction: This will obviously be because sentences just don't have meaning in isolation, so their meaning can't be given in terms of the sentences. |
| 22023 | Fichte's idea of spontaneity implied that nothing counts unless we give it status [Fichte, by Pinkard] |
| Full Idea: Fichte placed emphasis on human spontaneity, on nothing 'counting' for us unless we somehow bestowed some kind of status on it. | |
| From: report of Johann Fichte (The Science of Knowing (Wissenschaftslehre) [1st ed] [1794]) by Terry Pinkard - German Philosophy 1760-1860 06 | |
| A reaction: This idea evidentally arises from Kant's account of thought. Pinkard says this idea inspired the early Romantics. I would have thought the drive to exist (Spinoza's conatus) would make things count whether we liked it or not. |
| 13304 | Learned men gain more in one day than others do in a lifetime [Posidonius] |
| Full Idea: In a single day there lies open to men of learning more than there ever does to the unenlightened in the longest of lifetimes. | |
| From: Posidonius (fragments/reports [c.95 BCE]), quoted by Seneca the Younger - Letters from a Stoic 078 | |
| A reaction: These remarks endorsing the infinite superiority of the educated to the uneducated seem to have been popular in late antiquity. It tends to be the religions which discourage great learning, especially in their emphasis on a single book. |
| 22065 | Fichte reduces nature to a lifeless immobility [Schlegel,F on Fichte] |
| Full Idea: Fichte reduces the non-Ego or nature to a state of constant calm, standstill, immobility, lack of all change, movement and life, that is death. | |
| From: comment on Johann Fichte (The Science of Knowing (Wissenschaftslehre) [1st ed] [1794]) by Friedrich Schlegel - works vol 12 p.190 | |
| A reaction: The point is that Fichte's nature is a merely logical or conceptual deduction from the spontaneous reason of the self, so it can't have the lively diversity we find in nature. |
| 20820 | Time is an interval of motion, or the measure of speed [Posidonius, by Stobaeus] |
| Full Idea: Posidonius defined time thus: it is an interval of motion, or the measure of speed and slowness. | |
| From: report of Posidonius (fragments/reports [c.95 BCE]) by John Stobaeus - Anthology 1.08.42 | |
| A reaction: Hm. Can we define motion or speed without alluding to time? Looks like we have to define them as a conjoined pair, which means we cannot fully understand either of them. |