| 21675 | Some facts are indispensable for an effect, and others actually necessitate the effect [Stoic school, by Cicero] |
| Full Idea: The Stoics declare that there is a difference whether a thing is of such a kind that something cannot be effected without it, or such that something must necessarily be effected by it. | |
| From: report of Stoic school (fragments/reports [c.200 BCE]) by M. Tullius Cicero - On Fate ('De fato') 16.36 | |
| A reaction: This points out that causal preconditions can be either necessary or sufficient for their effect. Because it is a very perceptive point, I surmise that it originated with Chrysippus. |
| 13309 | That something is a necessary condition of something else doesn't mean it caused it [Seneca] |
| Full Idea: There's no reason for you to assume that, X being something without which Y could never have come about, Y came about as a result of the assistance of X. | |
| From: Seneca the Younger (Letters from a Stoic [c.60], 088) | |
| A reaction: This thought originates with Carneades, reported by Cicero. This is a clear message to the likes of Mackie, who are in danger of thinking that giving the preconditions of something is sufficient to give its causes. |
| 12633 | Definitions often give necessary but not sufficient conditions for an extension [Fodor] |
| Full Idea: Attempts to define a term frequently elicit necessary but not sufficient conditions for membership of its extension. This is called the 'X problem', as in 'kill' means 'cause to die' plus X. | |
| From: Jerry A. Fodor (LOT 2 [2008], Ch.2.1 n3) | |
| A reaction: Fodor is one of the great sceptics about definition. I just don't see why we have to have totally successful definitions before we can accept the process as a worthwhile endeavour. |
| 2963 | There may only be necessary and sufficient conditions (and counterfactuals) because we intervene in the world [Lockwood] |
| Full Idea: Perhaps notions of necessary and sufficient conditions, and counterfactual considerations, are in some way grounded in awareness of ourselves as active interveners and experimenters in the world, not passive spectators. | |
| From: Michael Lockwood (Mind, Brain and the Quantum [1989], p.155) |
| 3891 | If p entails q, then p is sufficient for q, and q is necessary for p [Scruton] |
| Full Idea: If p entails q, then p is sufficient for q, and q is necessary for p. | |
| From: Roger Scruton (Modern Philosophy:introduction and survey [1994], 15.7) |
| 4739 | In "if and only if" (iff), "if" expresses the sufficient condition, and "only if" the necessary condition [Engel] |
| Full Idea: Necessary and sufficient conditions are usually expressed by "if and only if" (abbr. "iff"), where "if" is the sufficient condition, and "only if" is the necessary condition. | |
| From: Pascal Engel (Truth [2002], §1.1) | |
| A reaction: 'I take my umbrella if and only if it is raining' (oh, and if I'm still alive). There may be other necessary conditions than the one specified. Oh, and I take it if my wife slips it into my car… |
| 14600 | Analysis aims at secure necessary and sufficient conditions [Schaffer,J] |
| Full Idea: An analysis is an attempt at providing finite, non-circular, and intuitively adequate necessary and sufficient conditions. | |
| From: Jonathan Schaffer (Causation and Laws of Nature [2008], 3) | |
| A reaction: Specifying the 'conditions' for something doesn't seem to quite add up to telling you what the thing is. A trivial side-effect might qualify as a sufficient condition for something, if it always happens. |
| 20388 | 'Necessary' conditions are requirements, and 'sufficient' conditions are guarantees [Davies,S] |
| Full Idea: A 'necessary' condition for something's being an X is condition that all Xs must satisfy. ...A 'sufficient' condition for something's being an X is a condition that, when satisfied, guarantees that what satisfies it is an X. | |
| From: Stephen Davies (The Philosophy of Art (2nd ed) [2016], 2.1) | |
| A reaction: By summarising this I arrive at the requirement/guarantee formulation, which I am rather pleased with. What is required for rain, and what guarantees rain? |