Tuesday, January 21, 2014

Terminology Tuesday: Necessary / Sufficient

Necessary / Sufficient: Distinction between logical or causal conditions.

In logic, one proposition is a necessary condition of another when the second cannot be true while the first is false, and one proposition is a sufficient condition for another when the first cannot be true while the second is false. Thus, for example: "I have a dog" is a necessary condition for "My dog has fleas," and "You scored ninety-five percent" is a sufficient condition for "You received an A."

In causal relations, a necessary condition for the occurence of an event is a state of affairs without which the event cannot happen, while a sufficient condition is a state of affairs that guarantees that it will happen. Thus, for example: the presence of oxygen is a necessary condition for combustion, and the flow of electrical current is a sufficient condition for the induction of a magnetic field.1

1. Philosophy Pages.

2 comments :

lance said...

how does the bible explain this kind of cause and effect relationship the non linear way like a plant not only needs moisture but also water and sunlight so as nurturing by humans?

Marc said...

lance:

I'm not sure what you mean by "the nonlinear way," and I'm not sure that the Bible (directly) addresses the issue you raised. But, I think it's reasonable to say that such things as water, sunlight, etc. appear to be necessary conditions for much of the plant life we find on Earth. If this is true, then much of the plant life we find on Earth wouldn't survive in the absence of such things as water, sunlight, etc.

Apologies if I happened to have misunderstood your question.

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