20 ideas
| 2666 | Carneades' pinnacles of philosophy are the basis of knowledge (the criterion of truth) and the end of appetite (good) [Carneades, by Cicero] |
| Full Idea: Carneades said the two greatest things in philosophy were the criterion of truth and the end of goods, and no man could be a sage who was ignorant of the existence of either a beginning of the process of knowledge or an end of appetition. | |
| From: report of Carneades (fragments/reports [c.174 BCE]) by M. Tullius Cicero - Academica II.09.29 | |
| A reaction: Nice, but I would want to emphasise the distinction between truth and its criterion. Admittedly we would have no truth without a good criterion, but the truth itself should be held in higher esteem than our miserable human means of grasping it. |
| 21390 | Future events are true if one day we will say 'this event is happening now' [Carneades] |
| Full Idea: We call those past events true of which at an earlier time this proposition was true: 'They are present now'; similarly, we shall call those future events true of which at some future time this proposition will be true: 'They are present now'. | |
| From: Carneades (fragments/reports [c.174 BCE]), quoted by M. Tullius Cicero - On Fate ('De fato') 9.23-8 | |
| A reaction: This is a very nice way of paraphrasing statements about the necessity of true future contingent events. It still relies, of course, on the veracity of a tensed assertion |
| 21672 | We say future things are true that will possess actuality at some following time [Carneades, by Cicero] |
| Full Idea: Just as we speak of past things as true that possessed true actuality at some former time, so we speak of future things as true that will possess true actuality at some following time. | |
| From: report of Carneades (fragments/reports [c.174 BCE]) by M. Tullius Cicero - On Fate ('De fato') 11.27 | |
| A reaction: This ducks the Aristotle problem of where it is true NOW when you say there will be a sea-fight tomorrow, and it turns out to be true. Carneades seems to be affirming a truth when it does not yet have a truthmaker. |
| 13913 | The four 'perfect syllogisms' are called Barbara, Celarent, Darii and Ferio [Engelbretsen/Sayward] |
| Full Idea: There are four 'perfect syllogisms': Barbara (every M is P, every S is M, so every S is P); Celarent (no M is P, every S is M, so no S is P); Darii (every M is P, some S is M, so some S is P); Ferio (no M is P, some S is M, so some S is not P). | |
| From: Engelbretsen,G/Sayward,C (Philosophical Logic: Intro to Advanced Topics [2011], 8) | |
| A reaction: The four names are mnemonics from medieval universities. |
| 13914 | Syllogistic logic has one rule: what is affirmed/denied of wholes is affirmed/denied of their parts [Engelbretsen/Sayward] |
| Full Idea: It has often been claimed (e.g. by Leibniz) that a single rule governs all syllogistic validity, called 'dictum de omni et null', which says that what is affirmed or denied of any whole is affirmed or denied of any part of that whole. | |
| From: Engelbretsen,G/Sayward,C (Philosophical Logic: Intro to Advanced Topics [2011], 8) | |
| A reaction: This seems to be the rule which is captured by Venn Diagrams. |
| 13915 | Syllogistic can't handle sentences with singular terms, or relational terms, or compound sentences [Engelbretsen/Sayward] |
| Full Idea: Three common kinds of sentence cannot be put into syllogistic ('categorical') form: ones using singular terms ('Mars is red'), ones using relational terms ('every painter owns some brushes'), and compound sentences. | |
| From: Engelbretsen,G/Sayward,C (Philosophical Logic: Intro to Advanced Topics [2011], 8) |
| 13916 | Term logic uses expression letters and brackets, and '-' for negative terms, and '+' for compound terms [Engelbretsen/Sayward] |
| Full Idea: Term logic begins with expressions and two 'term functors'. Any simple letter is a 'term', any term prefixed by a minus ('-') is a 'negative term', and any pair of terms flanking a plus ('+') is a 'compound term'. Parenthese are used for grouping. | |
| From: Engelbretsen,G/Sayward,C (Philosophical Logic: Intro to Advanced Topics [2011], 8) | |
| A reaction: [see Engelbretsen and Sayward for the full formal system] |
| 13850 | In modern logic all formal validity can be characterised syntactically [Engelbretsen/Sayward] |
| Full Idea: One of the key ideas of modern formal logic is that all formally valid inferences can be specified in strictly syntactic terms. | |
| From: Engelbretsen,G/Sayward,C (Philosophical Logic: Intro to Advanced Topics [2011], Ch.2) |
| 13849 | Classical logic rests on truth and models, where constructivist logic rests on defence and refutation [Engelbretsen/Sayward] |
| Full Idea: Classical logic rests on the concepts of truth and falsity (and usually makes use of a semantic theory based on models), whereas constructivist logic accounts for inference in terms of defense and refutation. | |
| From: Engelbretsen,G/Sayward,C (Philosophical Logic: Intro to Advanced Topics [2011], Intro) | |
| A reaction: My instincts go with the classical view, which is that inferences do not depend on the human capacity to defend them, but sit there awaiting revelation. My view isn't platonist, because I take the inferences to be rooted in the physical world. |
| 13851 | Unlike most other signs, = cannot be eliminated [Engelbretsen/Sayward] |
| Full Idea: Unlike ∨, →, ↔, and ∀, the sign = is not eliminable from a logic. | |
| From: Engelbretsen,G/Sayward,C (Philosophical Logic: Intro to Advanced Topics [2011], Ch.3) |
| 13852 | Axioms are ω-incomplete if the instances are all derivable, but the universal quantification isn't [Engelbretsen/Sayward] |
| Full Idea: A set of axioms is said to be ω-incomplete if, for some universal quantification, each of its instances is derivable from those axioms but the quantification is not thus derivable. | |
| From: Engelbretsen,G/Sayward,C (Philosophical Logic: Intro to Advanced Topics [2011], 7) |
| 15825 | Carneades denied the transitivity of identity [Carneades, by Chisholm] |
| Full Idea: Carneades denied the principle of the transitivity of identity. | |
| From: report of Carneades (fragments/reports [c.174 BCE], fr 41-42) by Roderick Chisholm - Person and Object 3.1 | |
| A reaction: Chisholm calls this 'extreme', but I assume Carneades wouldn't deny the principle in mathematics. I'm guessing that he just means that nothing ever stays quite the same. |
| 21389 | Carneades distinguished logical from causal necessity, when talking of future events [Long on Carneades] |
| Full Idea: From 'E will take place is true' it follows that E must take place. But 'must' here is logical not causal necessity. It is a considerable achievement of Carneades to have distinguished these two senses of necessity. | |
| From: comment on Carneades (fragments/reports [c.174 BCE]) by A.A. Long - Hellenistic Philosophy 3 | |
| A reaction: Personally I am inclined to think 'necessity' is univocal, and does not have two senses. What Carneades has nicely done is distinguish the two different grounds for the necessities. |
| 8840 | There are five possible responses to the problem of infinite regress in justification [Cleve] |
| Full Idea: Sceptics respond to the regress problem by denying knowledge; Foundationalists accept justifications without reasons; Positists say reasons terminate is mere posits; Coherentists say mutual support is justification; Infinitists accept the regress. | |
| From: James Van Cleve (Why coherence is not enough [2005], I) | |
| A reaction: A nice map of the territory. The doubts of Scepticism are not strong enough for anyone to embrace the view; Foundationalist destroy knowledge (?), as do Positists; Infinitism is a version of Coherentism - which is the winner. |
| 8841 | Modern foundationalists say basic beliefs are fallible, and coherence is relevant [Cleve] |
| Full Idea: Contemporary foundationalists are seldom of the strong Cartesian variety: they do not insist that basic beliefs be absolutely certain. They also tend to allow that coherence can enhance justification. | |
| From: James Van Cleve (Why coherence is not enough [2005], III) | |
| A reaction: It strikes me that they have got onto a slippery slope. How certain are the basic beliefs? How do you evaluate their certainty? Could incoherence in their implications undermine them? Skyscrapers need perfect foundations. |
| 21671 | Voluntary motion is intrinsically within our power, and this power is its cause [Carneades, by Cicero] |
| Full Idea: Voluntary motion possesses the intrinsic property of being in our power and of obeying us, and its obedience is not uncaused, for its nature is itself the cause of this. | |
| From: report of Carneades (fragments/reports [c.174 BCE]) by M. Tullius Cicero - On Fate ('De fato') 11.25 | |
| A reaction: To say that actions arise from our 'intrinsic power' is not much of an explanation, but it is still informative - that you should study the intrinsic powers of humans if you want to explain it. |
| 21391 | Some actions are within our power; determinism needs prior causes for everything - so it is false [Carneades, by Cicero] |
| Full Idea: Now something is in our power; but if everything happens as a result of destiny all things happen as a result of antecedent causes; therefore what happens does not happen as a result of destiny. | |
| From: report of Carneades (fragments/reports [c.174 BCE]) by M. Tullius Cicero - On Fate ('De fato') 14.31 | |
| A reaction: This invites the question of whether some things really are 'in our power'. Carneades (as expressed by Cicero) takes that for granted. Our 'power' may be antecedent causes in disguise. |
| 21674 | Even Apollo can only foretell the future when it is naturally necessary [Carneades, by Cicero] |
| Full Idea: Carneades used to say that not even Apollo could tell any future events except those whose causes were so held together that they must necessarily happen. | |
| From: report of Carneades (fragments/reports [c.174 BCE]) by M. Tullius Cicero - On Fate ('De fato') 14.32 | |
| A reaction: Carneades is opposing the usual belief in divination, where even priests can foretell contingent future events to some extent. Careneades, of course, was defending free will. |
| 7398 | Carneades said that after a shipwreck a wise man would seize the only plank by force [Carneades, by Tuck] |
| Full Idea: Carneades argued forcefully that in the event of a shipwreck, the wise man would be prepared to seize the only plank capable of bearing him to shore, even if that meant pushing another person off it. | |
| From: report of Carneades (fragments/reports [c.174 BCE]) by Richard Tuck - Hobbes Ch.1 | |
| A reaction: [source for this?] This thought seems to have provoked great discussion in the sixteenth century (mostly sympathetic). I can't help thinking the right answer depends on assessing your rival. Die for a hero, drown a nasty fool. |
| 21392 | People change laws for advantage; either there is no justice, or it is a form of self-injury [Carneades, by Lactantius] |
| Full Idea: The same people often changed laws according to circumstances; there is no natural law. There is no such thing as justice or, if there is, it is the height of folly, since a man injures himself in taking thought for the advantage of others. | |
| From: report of Carneades (fragments/reports [c.174 BCE]) by Lactantius - Institutiones Divinae 5.16.4 | |
| A reaction: [An argument used by Carneades on his notorious 156BCE visit to Rome, where he argued both for and against justice] This is probably the right wing view of justice. Why give other people what they want, if it is at our expense? |