8 ideas
| 1489 | Modern philosophy tends to be a theory-constructing extension of science, but there is also problem-solving [Nagel] |
| Full Idea: Philosophy is now dominated by a spirit of theory construction which sees philosophy as continuous with science, but the other problem-centred style is still in existence and it is important to keep it alive. | |
| From: Thomas Nagel (The Philosophical Culture [1995], §6) |
| 13768 | Validity can preserve certainty in mathematics, but conditionals about contingents are another matter [Edgington] |
| Full Idea: If your interest in logic is confined to applications to mathematics or other a priori matters, it is fine for validity to preserve certainty, ..but if you use conditionals when arguing about contingent matters, then great caution will be required. | |
| From: Dorothy Edgington (Conditionals [2001], 17.2.1) |
| 13770 | There are many different conditional mental states, and different conditional speech acts [Edgington] |
| Full Idea: As well as conditional beliefs, there are conditional desires, hopes, fears etc. As well as conditional statements, there are conditional commands, questions, offers, promises, bets etc. | |
| From: Dorothy Edgington (Conditionals [2001], 17.3.4) |
| 13764 | Are conditionals truth-functional - do the truth values of A and B determine the truth value of 'If A, B'? [Edgington] |
| Full Idea: Are conditionals truth-functional - do the truth values of A and B determine the truth value of 'If A, B'? Are they non-truth-functional, like 'because' or 'before'? Do the values of A and B, in some cases, leave open the value of 'If A,B'? | |
| From: Dorothy Edgington (Conditionals [2001], 17.1) | |
| A reaction: I would say they are not truth-functional, because the 'if' asserts some further dependency relation that goes beyond the truth or falsity of A and B. Logical ifs, causal ifs, psychological ifs... The material conditional ⊃ is truth-functional. |
| 13765 | 'If A,B' must entail ¬(A & ¬B); otherwise we could have A true, B false, and If A,B true, invalidating modus ponens [Edgington] |
| Full Idea: If it were possible to have A true, B false, and If A,B true, it would be unsafe to infer B from A and If A,B: modus ponens would thus be invalid. Hence 'If A,B' must entail ¬(A & ¬B). | |
| From: Dorothy Edgington (Conditionals [2001], 17.1) | |
| A reaction: This is a firm defence of part of the truth-functional view of conditionals, and seems unassailable. The other parts of the truth table are open to question, though, if A is false, or they are both true. |
| 16634 | I can't be unaware of anything which is in me [Descartes] |
| Full Idea: Nothing can be in me of which I am entirely unaware. | |
| From: René Descartes (Reply to First Objections [1641]), quoted by Robert Pasnau - Metaphysical Themes 1274-1671 08.4 | |
| A reaction: This I take to be a place where Descartes is utterly and catastrophically wrong. Until you grasp the utter falseness of this thought, the possibility of you (dear reader) understanding human beings is zero. Here 'I' obviously means his mind. |
| 3635 | Essence must be known before we discuss existence [Descartes] |
| Full Idea: According to the laws of true logic, we must never ask about the existence of anything until we first understand its essence. | |
| From: René Descartes (Reply to First Objections [1641], 108) |
| 3634 | We can't prove a first cause from our inability to grasp infinity [Descartes] |
| Full Idea: My inability to grasp an infinite chain of successive causes without a first cause does not entail that there must be a first cause, just as my inability to grasp infinite divisibility of finite things does not make that impossible. | |
| From: René Descartes (Reply to First Objections [1641], 106) |