14 ideas
| 15045 | The big issue since the eighteenth century has been: what is Reason? Its effect, limits and dangers? [Foucault] |
| Full Idea: I think the central issue of philosophy and critical thought since the eighteenth century has always been, still is, and will, I hope, remain the question: What is this Reason that we use? What are its historical effects? What are its limits and dangers? | |
| From: Michel Foucault (Space, Knowledge and Power (interview) [1982], p.358) | |
| A reaction: One can hardly deny the fairness of the question, but I hope that won't prevent us from trying to be rational. Maybe logicians do a better job of clarifying reason than the political and historical speculations of Foucault? |
| 11211 | If a sound conclusion comes from two errors that cancel out, the path of the argument must matter [Rumfitt] |
| Full Idea: If a designated conclusion follows from the premisses, but the argument involves two howlers which cancel each other out, then the moral is that the path an argument takes from premisses to conclusion does matter to its logical evaluation. | |
| From: Ian Rumfitt ("Yes" and "No" [2000], II) | |
| A reaction: The drift of this is that our view of logic should be a little closer to the reasoning of ordinary language, and we should rely a little less on purely formal accounts. |
| 11210 | Standardly 'and' and 'but' are held to have the same sense by having the same truth table [Rumfitt] |
| Full Idea: If 'and' and 'but' really are alike in sense, in what might that likeness consist? Some philosophers of classical logic will reply that they share a sense by virtue of sharing a truth table. | |
| From: Ian Rumfitt ("Yes" and "No" [2000]) | |
| A reaction: This is the standard view which Rumfitt sets out to challenge. |
| 11212 | The sense of a connective comes from primitively obvious rules of inference [Rumfitt] |
| Full Idea: A connective will possess the sense that it has by virtue of its competent users' finding certain rules of inference involving it to be primitively obvious. | |
| From: Ian Rumfitt ("Yes" and "No" [2000], III) | |
| A reaction: Rumfitt cites Peacocke as endorsing this view, which characterises the logical connectives by their rules of usage rather than by their pure semantic value. |
| 11214 | We learn 'not' along with affirmation, by learning to either affirm or deny a sentence [Rumfitt] |
| Full Idea: The standard view is that affirming not-A is more complex than affirming the atomic sentence A itself, with the latter determining its sense. But we could learn 'not' directly, by learning at once how to either affirm A or reject A. | |
| From: Ian Rumfitt ("Yes" and "No" [2000], IV) | |
| A reaction: [compressed] This seems fairly anti-Fregean in spirit, because it looks at the psychology of how we learn 'not' as a way of clarifying what we mean by it, rather than just looking at its logical behaviour (and thus giving it a secondary role). |
| 21243 | An existing thing is even greater if its non-existence is inconceivable [Anselm] |
| Full Idea: Something can be thought of as existing, which cannot be thought of as not existing, and this is greater than that which cannot be thought of as not existing. | |
| From: Anselm (Proslogion [1090], Ch 3) | |
| A reaction: This is a necessary addition, to single out the concept of God as special. But you really must give reasons for saying God's non-existence is inconceivable. Atheists seem to manage. |
| 21244 | Conceiving a greater being than God leads to absurdity [Anselm] |
| Full Idea: If some mind could think of something better than thou, the creature would rise above the Creator and judge its Creator; but this is altogether absurd. | |
| From: Anselm (Proslogion [1090], Ch 3) | |
| A reaction: An error, revealing a certain desperation. If a greafer being could be conceived than the being so far imagined as God (a necessarily existing being), that being would BE God, by his own argument (and not some arrogant 'creature'). |
| 21241 | Even the fool can hold 'a being than which none greater exists' in his understanding [Anselm] |
| Full Idea: Even the fool must be convinced that a being than which none greater can be thought exists at least in his understanding, since when he hears this he understands it, and whatever is understood is in the understanding. | |
| From: Anselm (Proslogion [1090], Ch 2) | |
| A reaction: Psalm 14.1: 'The fool hath said in his heart, there is no God'. But how does the fool interpret the words, if he has limited imagination? He might get no further than an attractive film star. He would need prompting to think of a spiritual being. |
| 21242 | If that than which a greater cannot be thought actually exists, that is greater than the mere idea [Anselm] |
| Full Idea: Clearly that than which a greater cannot be thought cannot exist in the understanding alone. For it it is actually in the understanding alone, it can be thought of as existing also in reality, and this is greater. | |
| From: Anselm (Proslogion [1090], Ch 2) | |
| A reaction: The suppressed premise is 'something actually existing is greater than the mere conception of it'. As it stands this is wrong. I can imagine a supreme evil. But see Idea 21243. |
| 1421 | A perfection must be independent and unlimited, and the necessary existence of Anselm's second proof gives this [Malcolm on Anselm] |
| Full Idea: Anselm's second proof works, because he sees that necessary existence (or the impossibility of non-existence) really is a perfection. This is because a perfection requires no dependence or limit or impediment. | |
| From: comment on Anselm (Proslogion [1090], Ch 3) by Norman Malcolm - Anselm's Argument Sect II | |
| A reaction: I have the usual problem, that it doesn't seem to follow that the perfect existence of something bestows a perfection. It may be necessary that 'for every large animal there exists a disease'. Satan may exist necessarily. |
| 21245 | The word 'God' can be denied, but understanding shows God must exist [Anselm] |
| Full Idea: We think of a thing when we say the world, and in another way when we think of the very thing itself. In the second sense God cannot be thought of as nonexistent. No one who understands can think God does not exist. | |
| From: Anselm (Proslogion [1090], Ch 4) | |
| A reaction: It seems open to the atheist to claim the exact opposite - that you can commit to God's existence if it is just a word, but understanding shows that God is impossible (perhaps because of contradictions). How to arbitrate? |
| 21246 | Guanilo says a supremely fertile island must exist, just because we can conceive it [Anselm] |
| Full Idea: Guanilo supposes that we imagine an island surpassing all lands in its fertility. We might then say that we cannot doubt that it truly exists is reality, because anyone can conceive it from a verbal description. | |
| From: Anselm (Proslogion [1090], Reply 3) | |
| A reaction: Guanilo was a very naughty monk, who must have had sleepless nights over this. One could further ask whether an island might have necessary existence. Anselm needs 'a being' to be a special category of thing. |
| 21247 | Nonexistence is impossible for the greatest thinkable thing, which has no beginning or end [Anselm] |
| Full Idea: If anyone does think of something a greater than which cannot be thought, then he thinks of something which cannot be thought of as nonexistent, ...for then it could be thought of as having a beginning and an end. And this is impossible. | |
| From: Anselm (Proslogion [1090], Reply 3) | |
| A reaction: A nice idea, but it has a flip side. If the atheist denies God's existence, then it follows that (because no beginning is possible for such a being) the existence of God is impossible. Anselm adds that contingent existents have parts (unlike God). |
| 1420 | Anselm's first proof fails because existence isn't a real predicate, so it can't be a perfection [Malcolm on Anselm] |
| Full Idea: Anselm's first proof fails, because he treats existence as being a perfection, which it isn't, because that would make it a real predicate. | |
| From: comment on Anselm (Proslogion [1090], Ch 2) by Norman Malcolm - Anselm's Argument Sect I | |
| A reaction: Not everyone accepts Kant's claim that existence cannot be a predicate. They all seem to know what a perfection is. Can the Mona Lisa (an object) not be a perfection? Must it be broken down into perfect predicates? |