65 ideas
21405 | Cicero sees wisdom in terms of knowledge, but earlier Stoics saw it as moral [Cicero, by Long] |
20871 | Unfortunately we choose a way of life before we are old enough to think clearly [Cicero] |
5893 | A wise man has integrity, firmness of will, nobility, consistency, sobriety, patience [Cicero] |
5891 | Philosophy is the collection of rational arguments [Cicero] |
2661 | Dialectic is speech cast in the form of logical argument [Cicero] |
2653 | If the parts of the universe are subject to the law of nature, the whole universe must also be subject to it [Cicero] |
2673 | There cannot be more than one truth [Cicero] |
17749 | Post proved the consistency of propositional logic in 1921 [Walicki] |
17765 | Propositional language can only relate statements as the same or as different [Walicki] |
17764 | Boolean connectives are interpreted as functions on the set {1,0} [Walicki] |
17752 | The empty set is useful for defining sets by properties, when the members are not yet known [Walicki] |
17753 | The empty set avoids having to take special precautions in case members vanish [Walicki] |
17759 | Ordinals play the central role in set theory, providing the model of well-ordering [Walicki] |
17741 | To determine the patterns in logic, one must identify its 'building blocks' [Walicki] |
21677 | How can the not-true fail to be false, or the not-false fail to be true? [Cicero] |
2669 | Dialectic assumes that all statements are either true or false, but self-referential paradoxes are a big problem [Cicero] |
17747 | A 'model' of a theory specifies interpreting a language in a domain to make all theorems true [Walicki] |
17748 | The L-S Theorem says no theory (even of reals) says more than a natural number theory [Walicki] |
17761 | A compact axiomatisation makes it possible to understand a field as a whole [Walicki] |
17763 | Axiomatic systems are purely syntactic, and do not presuppose any interpretation [Walicki] |
17758 | Ordinals are transitive sets of transitive sets; or transitive sets totally ordered by inclusion [Walicki] |
17755 | Ordinals are the empty set, union with the singleton, and any arbitrary union of ordinals [Walicki] |
17756 | The union of finite ordinals is the first 'limit ordinal'; 2ω is the second... [Walicki] |
17760 | Two infinite ordinals can represent a single infinite cardinal [Walicki] |
17757 | Members of ordinals are ordinals, and also subsets of ordinals [Walicki] |
17762 | In non-Euclidean geometry, all Euclidean theorems are valid that avoid the fifth postulate [Walicki] |
17754 | Inductive proof depends on the choice of the ordering [Walicki] |
17742 | Scotus based modality on semantic consistency, instead of on what the future could allow [Walicki] |
2664 | If we have complete healthy senses, what more could the gods give us? [Cicero] |
2665 | How can there be a memory of what is false? [Cicero] |
20800 | Every true presentation can have a false one of the same quality [Cicero] |
5879 | The soul is the heart, or blood in the heart, or part of the brain, of something living in heart or brain, or breath [Cicero] |
5884 | How can one mind perceive so many dissimilar sensations? [Cicero] |
5887 | The soul has a single nature, so it cannot be divided, and hence it cannot perish [Cicero] |
5886 | Like the eye, the soul has no power to see itself, but sees other things [Cicero] |
6029 | Whoever knows future causes knows everything that will be [Cicero] |
2628 | Why would mind mix with matter if it didn't need it? [Cicero] |
5885 | Souls contain no properties of elements, and elements contain no properties of souls [Cicero] |
21667 | Oratory and philosophy are closely allied; orators borrow from philosophy, and ornament it [Cicero] |
20814 | Eloquence educates, exhorts, comforts, distracts and unites us, and raises us from savagery [Cicero] |
21678 | If desire is not in our power then neither are choices, so we should not be praised or punished [Cicero] |
2672 | Virtues must be very detached, to avoid being motivated by pleasure [Cicero] |
5890 | We should not share the distress of others, but simply try to relieve it [Cicero] |
5894 | All men except philosophers fear poverty [Cicero] |
6031 | The essence of propriety is consistency [Cicero] |
5895 | If one despises illiterate mechanics individually, they are not worth more collectively [Cicero] |
2640 | We have the death penalty, but still have thousands of robbers [Cicero] |
2652 | Some regard nature simply as an irrational force that imparts movement [Cicero] |
22745 | Pherecydes said the first principle and element is earth [Pherecydes, by Sext.Empiricus] |
2645 | Why shouldn't the gods fear their own destruction? [Cicero] |
2627 | I wonder whether loss of reverence for the gods would mean the end of all virtue [Cicero] |
2651 | God doesn't obey the laws of nature; they are subject to the law of God [Cicero] |
2634 | It seems clear to me that we have an innate idea of the divine [Cicero] |
2636 | Many primitive people know nothing of the gods [Cicero] |
2655 | If the barbarians of Britain saw a complex machine, they would be baffled, but would know it was designed [Cicero] |
2656 | Chance is no more likely to create the world than spilling lots of letters is likely to create a famous poem [Cicero] |
2650 | If a person cannot feel the power of God when looking at the stars, they are probably incapable of feeling [Cicero] |
2647 | It is obvious from order that someone is in charge, as when we visit a gymnasium [Cicero] |
2657 | If everything with regular movement and order is divine, then recurrent illnesses must be divine [Cicero] |
2638 | Either the gods are identical, or one is more beautiful than another [Cicero] |
2635 | The gods are happy, so virtuous, so rational, so must have human shape [Cicero] |
2641 | Why believe in gods if you have never seen them? [Cicero] |
5883 | Pherecydes was the first to say that the soul is eternal [Pherecydes, by Cicero] |
2659 | The lists of good men who have suffered and bad men who have prospered are endless [Cicero] |
2658 | The gods blame men for having vices, but they could have given us enough reason to avoid them [Cicero] |