21 ideas
| 21970 | Philosophy attains its goal if one person feels perfect accord between their system and experience [Fichte] |
| Full Idea: If even a single person is completely convinced of his philosophy; ...if his free judgement in philosophising, and what life obtrudes upon him, are perfectly in accord; then in this person philosophy has completed its circuit and attained its goal. | |
| From: Johann Fichte (works [1798], I:512), quoted by A.W. Moore - The Evolution of Modern Metaphysics 06.4 | |
| A reaction: Interesting to hear a famous idealist offering accordance with real life as a criterion for philosophical success. But that is real life, but not as you and I may know it.... His criterion is very subjective. A bad philosopher might attain it? |
| 6912 | For Fichte there is no God outside the ego, and 'our religion is reason' [Fichte, by Feuerbach] |
| Full Idea: For Fichte there is no God outside the ego, and 'our religion is reason'. | |
| From: report of Johann Fichte (works [1798]) by Ludwig Feuerbach - Principles of Philosophy of the Future §17 | |
| A reaction: Fichte was not an atheist, but this seems to be a supreme aphorism for summarising our image of the Englightenment. Personally I subscribe to the Enlightenment ideal (the best life is the rational life), despite doubts about 'pure' reason. |
| 13011 | New axioms are being sought, to determine the size of the continuum [Maddy] |
| Full Idea: In current set theory, the search is on for new axioms to determine the size of the continuum. | |
| From: Penelope Maddy (Believing the Axioms I [1988], §0) | |
| A reaction: This sounds the wrong way round. Presumably we seek axioms that fix everything else about set theory, and then check to see what continuum results. Otherwise we could just pick our continuum, by picking our axioms. |
| 13013 | The Axiom of Extensionality seems to be analytic [Maddy] |
| Full Idea: Most writers agree that if any sense can be made of the distinction between analytic and synthetic, then the Axiom of Extensionality should be counted as analytic. | |
| From: Penelope Maddy (Believing the Axioms I [1988], §1.1) | |
| A reaction: [Boolos is the source of the idea] In other words Extensionality is not worth discussing, because it simply tells you what the world 'set' means, and there is no room for discussion about that. The set/class called 'humans' varies in size. |
| 13014 | Extensional sets are clearer, simpler, unique and expressive [Maddy] |
| Full Idea: The extensional view of sets is preferable because it is simpler, clearer, and more convenient, because it individuates uniquely, and because it can simulate intensional notions when the need arises. | |
| From: Penelope Maddy (Believing the Axioms I [1988], §1.1) | |
| A reaction: [She cites Fraenkel, Bar-Hillet and Levy for this] The difficulty seems to be whether the extensional notion captures our ordinary intuitive notion of what constitutes a group of things, since that needs flexible size and some sort of unity. |
| 13021 | The Axiom of Infinity states Cantor's breakthrough that launched modern mathematics [Maddy] |
| Full Idea: The Axiom of Infinity is a simple statement of Cantor's great breakthrough. His bold hypothesis that a collection of elements that had lurked in the background of mathematics could be infinite launched modern mathematics. | |
| From: Penelope Maddy (Believing the Axioms I [1988], §1.5) | |
| A reaction: It also embodies one of those many points where mathematics seems to depart from common sense - but then most subjects depart from common sense when they get more sophisticated. Look what happened to art. |
| 13022 | Infinite sets are essential for giving an account of the real numbers [Maddy] |
| Full Idea: If one is interested in analysis then infinite sets are indispensable since even the notion of a real number cannot be developed by means of finite sets alone. | |
| From: Penelope Maddy (Believing the Axioms I [1988], §1.5) | |
| A reaction: [Maddy is citing Fraenkel, Bar-Hillel and Levy] So Cantor's great breakthrough (Idea 13021) actually follows from the earlier acceptance of the real numbers, so that's where the departure from common sense started. |
| 13023 | The Power Set Axiom is needed for, and supported by, accounts of the continuum [Maddy] |
| Full Idea: The Power Set Axiom is indispensable for a set-theoretic account of the continuum, ...and in so far as those attempts are successful, then the power-set principle gains some confirmatory support. | |
| From: Penelope Maddy (Believing the Axioms I [1988], §1.6) | |
| A reaction: The continuum is, of course, notoriously problematic. Have we created an extra problem in our attempts at solving the first one? |
| 13024 | Efforts to prove the Axiom of Choice have failed [Maddy] |
| Full Idea: Jordain made consistent and ill-starred efforts to prove the Axiom of Choice. | |
| From: Penelope Maddy (Believing the Axioms I [1988], §1.7) | |
| A reaction: This would appear to be the fate of most axioms. You would presumably have to use a different system from the one you are engaged with to achieve your proof. |
| 13025 | Modern views say the Choice set exists, even if it can't be constructed [Maddy] |
| Full Idea: Resistance to the Axiom of Choice centred on opposition between existence and construction. Modern set theory thrives on a realistic approach which says the choice set exists, regardless of whether it can be defined, constructed, or given by a rule. | |
| From: Penelope Maddy (Believing the Axioms I [1988], §1.7) | |
| A reaction: This seems to be a key case for the ontology that lies at the heart of theory. Choice seems to be an invaluable tool for proofs, so it won't go away, so admit it to the ontology. Hm. So the tools of thought have existence? |
| 13026 | A large array of theorems depend on the Axiom of Choice [Maddy] |
| Full Idea: Many theorems depend on the Axiom of Choice, including that a countable union of sets is countable, and results in analysis, topology, abstract algebra and mathematical logic. | |
| From: Penelope Maddy (Believing the Axioms I [1988], §1.7) | |
| A reaction: The modern attitude seems to be to admit anything if it leads to interesting results. It makes you wonder about the modern approach of using mathematics and logic as the cutting edges of ontological thinking. |
| 13019 | The Iterative Conception says everything appears at a stage, derived from the preceding appearances [Maddy] |
| Full Idea: The Iterative Conception (Zermelo 1930) says everything appears at some stage. Given two objects a and b, let A and B be the stages at which they first appear. Suppose B is after A. Then the pair set of a and b appears at the immediate stage after B. | |
| From: Penelope Maddy (Believing the Axioms I [1988], §1.3) | |
| A reaction: Presumably this all happens in 'logical time' (a nice phrase I have just invented!). I suppose we might say that the existence of the paired set is 'forced' by the preceding sets. No transcendental inferences in this story? |
| 13018 | Limitation of Size is a vague intuition that over-large sets may generate paradoxes [Maddy] |
| Full Idea: The 'limitation of size' is a vague intuition, based on the idea that being too large may generate the paradoxes. | |
| From: Penelope Maddy (Believing the Axioms I [1988], §1.3) | |
| A reaction: This is an intriguing idea to be found right at the centre of what is supposed to be an incredibly rigorous system. |
| 21973 | Fichte believed in things-in-themselves [Fichte, by Moore,AW] |
| Full Idea: Fichte retained a broadly Kantian conception of how things are in themselves. | |
| From: report of Johann Fichte (works [1798]) by A.W. Moore - The Evolution of Modern Metaphysics 07.2 | |
| A reaction: The contrast is between those who believe in the thing-in-itself, while admitting that we can't know it, and those who deny such a thing. The debate returned 130 years later as verificationism in language. |
| 21914 | We can deduce experience from self-consciousness, without the thing-in-itself [Fichte] |
| Full Idea: We can abandon the thing-in-itself, and aim for 'a complete deduction of all experience from the possibility of self-consciousness'. | |
| From: Johann Fichte (works [1798], I p.425), quoted by Peter B. Lewis - Schopenhauer 3 | |
| A reaction: German Idealism now looks to me like a weird abberation in the history of philosophy, though no doubt it has (like every philosophical theory) some supporters out there somewhere. Schopenhauer called this 'raving nonsense'. |
| 20951 | The absolute I divides into consciousness, and a world which is not-I [Fichte, by Bowie] |
| Full Idea: Fichte's very influential idea is that the subject becomes divided against itself. The absolute I splits into an I (consciousness) and a not-I (the objective world) that are relative to each other. | |
| From: report of Johann Fichte (works [1798]) by Andrew Bowie - Introduction to German Philosophy 3 'Fichtean' | |
| A reaction: This is German Idealism in action. Is there a before and after the split here? I can't make much sense of this idea. It is said that babies spend a while deciding which bits are them and which aren't. There is more to the world than 'not-I'. |
| 21964 | Reason arises from freedom, so philosophy starts from the self, and not from the laws of nature [Fichte] |
| Full Idea: Not by any law of nature do we attain to reason; we achieve it by absolute freedom. ...In philosophy, therefore, we must necessarily start from the self. The materialists' project of deriving the appearance of reason from natural laws is impossible. | |
| From: Johann Fichte (works [1798], I:298), quoted by A.W. Moore - The Evolution of Modern Metaphysics | |
| A reaction: I blame Descartes' Cogito for this misunderstanding. The underlying idea (in Kant, and probably earlier) is that pure reason needs pure free will. Modern thought usually sees reason as extremely impure. |
| 21968 | Abandon the thing-in-itself; things only exist in relation to our thinking [Fichte] |
| Full Idea: We must be rid of the thing-in-itself; for whatever we may think, we are that which thinks therein, and hence nothing could ever come to exist independently of us, for everything is necessarily related to our thinking. | |
| From: Johann Fichte (works [1798], I:501), quoted by A.W. Moore - The Evolution of Modern Metaphysics 06.3 | |
| A reaction: Some statements of idealism are understandable, or even quite plausible, but this one sounds ridiculous. The idea that if human beings die out then reality ceases to exist is absurd humanistic vanity. |
| 21965 | Spinoza could not actually believe his determinism, because living requires free will [Fichte] |
| Full Idea: Spinoza could only think his philosophy, not believe it, for it stood in immediate contradiction to his necessary conviction in daily life, whereby he was bound to regard himself as free and independent. | |
| From: Johann Fichte (works [1798], I:513), quoted by A.W. Moore - The Evolution of Modern Metaphysics 06.2 | |
| A reaction: This seems to be invoking Kant's idea that we must presuppose free will, rather than an assertion that we actually have it. |
| 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. |
| 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. |