21 ideas
| 19740 | A very hungry man cannot choose between equidistant piles of food [Aristotle] |
| Full Idea: The man who, though exceedingly hungry and thirsty, and both equally, yet being equidistant from food and drink, is therefore bound to stay where he is. | |
| From: Aristotle (On the Heavens [c.336 BCE], 296b33) | |
| A reaction: This is, of course, Buridan's famous Ass, but this quotation has the advantage of precedence, and also of being expressed in an original quotation (which does not exist for Buridan). |
| 11984 | Asserting a possible property is to say it would have had the property if that world had been actual [Plantinga] |
| Full Idea: To say than x has a property in a possible world is simply to say that x would have had the property if that world had been actual. | |
| From: Alvin Plantinga (Transworld Identity or worldbound Individuals? [1973], I) | |
| A reaction: Plantinga tries to defuse all the problems with identity across possible worlds, by hanging on to subjunctive verbs and modal modifiers. The point, though, was to explain these, or at least to try to give their logical form. |
| 11980 | A possible world is a maximal possible state of affairs [Plantinga] |
| Full Idea: A possible world is just a maximal possible state of affairs. | |
| From: Alvin Plantinga (Transworld Identity or worldbound Individuals? [1973], I) | |
| A reaction: The key point here is that Plantinga includes the word 'possible' in his definition. Possibility defines the worlds, and so worlds cannot be used on their own to define possibility. |
| 11982 | If possible Socrates differs from actual Socrates, the Indiscernibility of Identicals says they are different [Plantinga] |
| Full Idea: If the Socrates of the actual world has snubnosedness but Socrates-in-W does not, this is surely inconsistent with the Indiscernibility of Identicals, a principle than which none sounder can be conceived. | |
| From: Alvin Plantinga (Transworld Identity or worldbound Individuals? [1973], I) | |
| A reaction: However, we allow Socrates to differ over time while remaining the same Socrates, so some similar approach should apply here. In both cases we need some notion of what is essential to Socrates. But what unites aged 3 with aged 70? |
| 11983 | It doesn't matter that we can't identify the possible Socrates; we can't identify adults from baby photos [Plantinga] |
| Full Idea: We may say it makes no sense to say that Socrates exists at a world, if there is in principle no way of identifying him. ...But this is confused. To suppose Agnew was a precocious baby, we needn't be able to pick him from a gallery of babies. | |
| From: Alvin Plantinga (Transworld Identity or worldbound Individuals? [1973], I) | |
| A reaction: This seems a good point, and yet we have a space-time line joining adult Agnew with baby Agnew, and no such causal link is available between persons in different possible worlds. What would be the criterion in each case? |
| 11985 | If individuals can only exist in one world, then they can never lack any of their properties [Plantinga] |
| Full Idea: The Theory of Worldbound Individuals contends that no object exists in more than one possible world; this implies the outrageous view that - taking properties in the broadest sense - no object could have lacked any property that it in fact has. | |
| From: Alvin Plantinga (Transworld Identity or worldbound Individuals? [1973], II) | |
| A reaction: Leibniz is the best known exponent of this 'outrageous view', though Plantinga shows that Lewis may be seen in the same light, since only counterparts are found in possible worlds, not the real thing. The Theory does seem wrong. |
| 11986 | The counterparts of Socrates have self-identity, but only the actual Socrates has identity-with-Socrates [Plantinga] |
| Full Idea: While Socrates has no counterparts that lack self-identity, he does have counterparts that lack identity-with-Socrates. He alone has that - the property, that is, of being identical with the object that in fact instantiates Socrateity. | |
| From: Alvin Plantinga (Transworld Identity or worldbound Individuals? [1973], II) | |
| A reaction: I am never persuaded by arguments which rest on such dubious pseudo-properties. Whether or not a counterpart of Socrates has any sort of identity with Socrates cannot be prejudged, as it would beg the question. |
| 11987 | Counterpart Theory absurdly says I would be someone else if things went differently [Plantinga] |
| Full Idea: It makes no sense to say I could have been someone else, yet Counterpart Theory implies not merely that I could have been distinct from myself, but that I would have been distinct from myself had things gone differently in even the most miniscule detail. | |
| From: Alvin Plantinga (Transworld Identity or worldbound Individuals? [1973], II) | |
| A reaction: A counterpart doesn't appear to be 'me being distinct from myself'. We have to combine counterparts over possible worlds with perdurance over time. I am a 'worm' of time-slices. Anything not in that worm is not strictly me. |
| 398 | Each thing that has a function is for the sake of that function [Aristotle] |
| Full Idea: Each thing that has a function is for the sake of that function. | |
| From: Aristotle (On the Heavens [c.336 BCE], 286a08) | |
| A reaction: This is the central idea of Aristotle's Ethics. Did it originate with Plato, or Socrates, the young pupil Aristotle? I suspect the strong influence of Aristotle on later Plato. A major idea. Functions link the facts to life. |
| 394 | An unworn sandal is in vain, but nothing in nature is in vain [Aristotle] |
| Full Idea: We say of a sandal which is not worn that it is in vain; God and nature, however, do nothing in vain. | |
| From: Aristotle (On the Heavens [c.336 BCE], 271a33) |
| 396 | There has to be some goal, and not just movement to infinity [Aristotle] |
| Full Idea: There has to be some goal, and not just movement to infinity. | |
| From: Aristotle (On the Heavens [c.336 BCE], 277a26) |
| 1748 | Archelaus was the first person to say that the universe is boundless [Archelaus, by Diog. Laertius] |
| Full Idea: Archelaus was the first person to say that the universe is boundless. | |
| From: report of Archelaus (fragments/reports [c.450 BCE]) by Diogenes Laertius - Lives of Eminent Philosophers 02.Ar.3 |
| 16102 | Aether moves in circles and is imperishable; the four elements perish, and move in straight lines [Aristotle, by Gill,ML] |
| Full Idea: For Aristotle, aether and the four sublunary elements obey different physical laws. Aether moves naturally in a circle and, unlike its lower counterparts, is not a source of perishability. The four sublunary elements move naturally in straight lines. | |
| From: report of Aristotle (On the Heavens [c.336 BCE]) by Mary Louise Gill - Aristotle on Substance Ch.2 | |
| A reaction: I think it is anachronistic for Gill to talk of 'obeying' and 'laws'. She should have said that they have different 'natures'. We can be amused by Greek errors, until we stare hard at the problems they were trying to solve. |
| 17463 | An element is what bodies are analysed into, and won't itself divide into something else [Aristotle] |
| Full Idea: An element is a body into which other bodies may be analyzed, present in them potentially or in actuality (which of these is still disputable), and not itself divisible into bodies different in form. That is what all men mean by element. | |
| From: Aristotle (On the Heavens [c.336 BCE], 302a05), quoted by Weisberg/Needham/Hendry - Philosophy of Chemistry 1.1 | |
| A reaction: This is the classic definition of an element, which endured for a long time, and has been replaced by an 'actual components' view. Obviously analysis nowadays goes well beyond the atoms. |
| 399 | If the more you raise some earth the faster it moves, why does the whole earth not move? [Aristotle] |
| Full Idea: If you raise some earth and release it, it moves and won't stay put, and the more you raise it the faster it moves, so why does the whole earth not move? | |
| From: Aristotle (On the Heavens [c.336 BCE], 294a12) |
| 20918 | Void is a kind of place, so it can't explain place [Aristotle] |
| Full Idea: It is absurd to explain place by the void, as though this latter were not itself some kind of place. | |
| From: Aristotle (On the Heavens [c.336 BCE], 309b24) | |
| A reaction: Presumably this is aimed at Democritus. |
| 402 | The Earth must be spherical, because it casts a convex shadow on the moon [Aristotle] |
| Full Idea: A lunar eclipse always has a convex dividing line, so, if it is eclipsed by the interposition of the earth, the circumference of the earth, being spherical, is responsible for the shape. | |
| From: Aristotle (On the Heavens [c.336 BCE], 297b29) |
| 403 | The earth must be round and of limited size, because moving north or south makes different stars visible [Aristotle] |
| Full Idea: Clearly the earth is round and not of great size, because when we move north or south we find that very different stars are visible. | |
| From: Aristotle (On the Heavens [c.336 BCE], 297b30) |
| 1498 | Everyone agrees that the world had a beginning, but thinkers disagree over whether it will end [Aristotle] |
| Full Idea: All thinkers agree that the world had a beginning, but some claim that, having come into existence, it is everlasting. | |
| From: Aristotle (On the Heavens [c.336 BCE], 279b12) |
| 395 | It seems possible that there exists a limited number of other worlds apart from this one [Aristotle] |
| Full Idea: One might indeed be puzzled whether, just as the world about us exists, nothing prevents there being others as well, certainly more than one, though not an unlimited number | |
| From: Aristotle (On the Heavens [c.336 BCE], 274a26) |
| 5989 | Archelaus said life began in a primeval slime [Archelaus, by Schofield] |
| Full Idea: Archelaus wrote that life on Earth began in a primeval slime. | |
| From: report of Archelaus (fragments/reports [c.450 BCE]) by Malcolm Schofield - Archelaus | |
| A reaction: This sounds like a fairly clearcut assertion of the production of life by evolution. Darwin's contribution was to propose the mechanism for achieving it. We should honour the name of Archelaus for this idea. |