102 ideas
| 7113 | Phenomenology assumes that all consciousness is of something [Sartre] |
| 9738 | Each line of a truth table is a model [Fitting/Mendelsohn] |
| 9727 | Modal logic adds □ (necessarily) and ◊ (possibly) to classical logic [Fitting/Mendelsohn] |
| 9726 | We let 'R' be the accessibility relation: xRy is read 'y is accessible from x' [Fitting/Mendelsohn] |
| 9737 | The symbol ||- is the 'forcing' relation; 'Γ ||- P' means that P is true in world Γ [Fitting/Mendelsohn] |
| 13136 | The prefix σ names a possible world, and σ.n names a world accessible from that one [Fitting/Mendelsohn] |
| 13727 | A 'constant' domain is the same for all worlds; 'varying' domains can be entirely separate [Fitting/Mendelsohn] |
| 9734 | Modern modal logic introduces 'accessibility', saying xRy means 'y is accessible from x' [Fitting/Mendelsohn] |
| 9736 | A 'model' is a frame plus specification of propositions true at worlds, written < G,R,||- > [Fitting/Mendelsohn] |
| 9735 | A 'frame' is a set G of possible worlds, with an accessibility relation R, written < G,R > [Fitting/Mendelsohn] |
| 9741 | Accessibility relations can be 'reflexive' (self-referring), 'transitive' (carries over), or 'symmetric' (mutual) [Fitting/Mendelsohn] |
| 13141 | Negation: if σ ¬¬X then σ X [Fitting/Mendelsohn] |
| 13138 | Disj: a) if σ ¬(X∨Y) then σ ¬X and σ ¬Y b) if σ X∨Y then σ X or σ Y [Fitting/Mendelsohn] |
| 13142 | Existential: a) if σ ◊X then σ.n X b) if σ ¬□X then σ.n ¬X [n is new] [Fitting/Mendelsohn] |
| 13144 | T reflexive: a) if σ □X then σ X b) if σ ¬◊X then σ ¬X [Fitting/Mendelsohn] |
| 13145 | D serial: a) if σ □X then σ ◊X b) if σ ¬◊X then σ ¬□X [Fitting/Mendelsohn] |
| 13146 | B symmetric: a) if σ.n □X then σ X b) if σ.n ¬◊X then σ ¬X [n occurs] [Fitting/Mendelsohn] |
| 13147 | 4 transitive: a) if σ □X then σ.n □X b) if σ ¬◊X then σ.n ¬◊X [n occurs] [Fitting/Mendelsohn] |
| 13148 | 4r rev-trans: a) if σ.n □X then σ □X b) if σ.n ¬◊X then σ ¬◊X [n occurs] [Fitting/Mendelsohn] |
| 9740 | If a proposition is possibly true in a world, it is true in some world accessible from that world [Fitting/Mendelsohn] |
| 9739 | If a proposition is necessarily true in a world, it is true in all worlds accessible from that world [Fitting/Mendelsohn] |
| 13137 | Conj: a) if σ X∧Y then σ X and σ Y b) if σ ¬(X∧Y) then σ ¬X or σ ¬Y [Fitting/Mendelsohn] |
| 13140 | Bicon: a)if σ(X↔Y) then σ(X→Y) and σ(Y→X) b) [not biconditional, one or other fails] [Fitting/Mendelsohn] |
| 13139 | Implic: a) if σ ¬(X→Y) then σ X and σ ¬Y b) if σ X→Y then σ ¬X or σ Y [Fitting/Mendelsohn] |
| 13143 | Universal: a) if σ ¬◊X then σ.m ¬X b) if σ □X then σ.m X [m exists] [Fitting/Mendelsohn] |
| 13149 | S5: a) if n ◊X then kX b) if n ¬□X then k ¬X c) if n □X then k X d) if n ¬◊X then k ¬X [Fitting/Mendelsohn] |
| 9742 | The system K has no accessibility conditions [Fitting/Mendelsohn] |
| 13114 | □P → P is not valid in D (Deontic Logic), since an obligatory action may be not performed [Fitting/Mendelsohn] |
| 9743 | The system D has the 'serial' conditon imposed on its accessibility relation [Fitting/Mendelsohn] |
| 9744 | The system T has the 'reflexive' conditon imposed on its accessibility relation [Fitting/Mendelsohn] |
| 9746 | The system K4 has the 'transitive' condition on its accessibility relation [Fitting/Mendelsohn] |
| 9745 | The system B has the 'reflexive' and 'symmetric' conditions on its accessibility relation [Fitting/Mendelsohn] |
| 9747 | The system S4 has the 'reflexive' and 'transitive' conditions on its accessibility relation [Fitting/Mendelsohn] |
| 9748 | System S5 has the 'reflexive', 'symmetric' and 'transitive' conditions on its accessibility relation [Fitting/Mendelsohn] |
| 9404 | Modality affects content, because P→◊P is valid, but ◊P→P isn't [Fitting/Mendelsohn] |
| 13112 | In epistemic logic knowers are logically omniscient, so they know that they know [Fitting/Mendelsohn] |
| 13111 | Read epistemic box as 'a knows/believes P' and diamond as 'for all a knows/believes, P' [Fitting/Mendelsohn] |
| 13113 | F: will sometime, P: was sometime, G: will always, H: was always [Fitting/Mendelsohn] |
| 13728 | The Barcan says nothing comes into existence; the Converse says nothing ceases; the pair imply stability [Fitting/Mendelsohn] |
| 13729 | The Barcan corresponds to anti-monotonicity, and the Converse to monotonicity [Fitting/Mendelsohn] |
| 9725 | 'Predicate abstraction' abstracts predicates from formulae, giving scope for constants and functions [Fitting/Mendelsohn] |
| 22227 | For Sartre there is only being for-itself, or being in-itself (which is beyond experience) [Sartre, by Daigle] |
| 13730 | The Indiscernibility of Identicals has been a big problem for modal logic [Fitting/Mendelsohn] |
| 13725 | □ must be sensitive as to whether it picks out an object by essential or by contingent properties [Fitting/Mendelsohn] |
| 13731 | Objects retain their possible properties across worlds, so a bundle theory of them seems best [Fitting/Mendelsohn] |
| 13726 | Counterpart relations are neither symmetric nor transitive, so there is no logic of equality for them [Fitting/Mendelsohn] |
| 7112 | The Cogito depends on a second-order experience, of being conscious of consciousness [Sartre] |
| 7114 | The consciousness that says 'I think' is not the consciousness that thinks [Sartre] |
| 7119 | Is the Cogito reporting an immediate experience of doubting, or the whole enterprise of doubting? [Sartre] |
| 20743 | Appearances do not hide the essence; appearances are the essence [Sartre] |
| 7122 | We can never, even in principle, grasp other minds, because the Ego is self-conceiving [Sartre] |
| 7125 | A consciousness can conceive of no other consciousness than itself [Sartre] |
| 7108 | The eternal truth of 2+2=4 is what gives unity to the mind which regularly thinks it [Sartre] |
| 24016 | Consciousness always transcends itself [Sartre] |
| 6151 | Sartre says consciousness is just directedness towards external objects [Sartre, by Rowlands] |
| 7111 | Consciousness exists as consciousness of itself [Sartre] |
| 22226 | Since we are a consciousness, Sartre entirely rejected the unconscious mind [Sartre, by Daigle] |
| 7107 | Intentionality defines, transcends and unites consciousness [Sartre] |
| 3847 | Man is nothing else but the sum of his actions [Sartre] |
| 7109 | If you think of '2+2=4' as the content of thought, the self must be united transcendentally [Sartre] |
| 7106 | The Ego is not formally or materially part of consciousness, but is outside in the world [Sartre] |
| 7117 | How could two I's, the reflective and the reflected, communicate with each other? [Sartre] |
| 7123 | Knowing yourself requires an exterior viewpoint, which is necessarily false [Sartre] |
| 22225 | My ego is more intimate to me, but not more certain than other egos [Sartre] |
| 7124 | The Ego never appears except when we are not looking for it [Sartre] |
| 7116 | When we are unreflective (as when chasing a tram) there is no 'I' [Sartre] |
| 7120 | It is theoretically possible that the Ego consists entirely of false memories [Sartre] |
| 7110 | If the 'I' is transcendental, it unnecessarily splits consciousness in two [Sartre] |
| 7115 | Maybe it is the act of reflection that brings 'me' into existence [Sartre] |
| 7121 | The Ego only appears to reflection, so it is cut off from the World [Sartre] |
| 3846 | Man IS freedom [Sartre] |
| 24013 | An emotion and its object form a unity, so emotion is a mode of apprehension [Sartre] |
| 24017 | Emotion is one of our modes of understanding our Being-in-the-World [Sartre] |
| 24014 | Emotions are a sort of bodily incantation which brings a magic to the world [Sartre] |
| 24015 | Emotions makes us believe in and live in a new world [Sartre] |
| 6164 | Sartre rejects mental content, and the idea that the mind has hidden inner features [Sartre, by Rowlands] |
| 7074 | Man is a useless passion [Sartre] |
| 3843 | There is no human nature [Sartre] |
| 6687 | Man is the desire to be God [Sartre] |
| 20762 | There are no values to justify us, and no excuses [Sartre] |
| 3852 | If values depend on us, freedom is the foundation of all values [Sartre] |
| 22228 | Sartre's freedom is not for whimsical action, but taking responsibility for our own values [Sartre, by Daigle] |
| 22233 | Love is the demand to be loved [Sartre] |
| 3031 | The greatest good is not the achievement of desire, but to desire what is proper [Menedemus, by Diog. Laertius] |
| 20764 | In becoming what we want to be we create what we think man ought to be [Sartre] |
| 3848 | Cowards are responsible for their cowardice [Sartre] |
| 20763 | When my personal freedom becomes involved, I must want freedom for everyone else [Sartre] |
| 22229 | Existentialists says that cowards and heroes make themselves [Sartre] |
| 20755 | Fear concerns the world, but 'anguish' comes from confronting my self [Sartre] |
| 3842 | Existence before essence (or begin with the subjective) [Sartre] |
| 6868 | 'Existence precedes essence' means we have no pre-existing self, but create it through existence [Sartre, by Le Poidevin] |
| 3844 | Existentialism says man is whatever he makes of himself [Sartre] |
| 20760 | Sincerity is not authenticity, because it only commits to one particular identity [Sartre, by Aho] |
| 22231 | We flee from the anguish of freedom by seeing ourselves objectively, as determined [Sartre] |
| 20754 | It is dishonest to offer passions as an excuse [Sartre] |
| 22230 | Sartre gradually realised that freedom is curtailed by the weight of situation [Sartre, by Daigle] |
| 22232 | Authenticity is taking responsibility for a situation, with all its risks and emotions [Sartre] |
| 3851 | If I do not choose, that is still a choice [Sartre] |
| 6571 | When a man must choose between his mother and the Resistance, no theory can help [Sartre, by Fogelin] |
| 20491 | States have a monopoly of legitimate violence [Sartre, by Wolff,J] |
| 21240 | The truth about events always comes from the oppressed and disadvantaged [Sartre, by Bakewell] |
| 3845 | Without God there is no intelligibility or value [Sartre] |