Why Tea wrote: > > > > How about this: Free software is a subset of open source software, so > > all free software is open source. > > This doesn't sound right. I don't think neither one is the subset of > the other. > > If freeware is a subset of Open Source, then all freeware is Open > Source. That's clearly NOT the case, is it?
Aside from difference on the meaning of "freeware" and "free software" some freeware is open source code and some is not-open source code, therefore it is not the case that all freeware is open source. Possibly all not-open source code is not freeware but some non-open-source code is freeware to, hence; Everyone is familiar with the concept of a necessary condition. For example, we all know that air is necessary for (human) life. Without air, there is no (human) life. Similarly, a microscope (or some other instrument) is necessary for human beings to see viruses. (Viruses are too small to be seen by the naked eye.) Similarly, everyone is familiar with the concept of a sufficient condition. For example, it suffices (i.e. it is sufficient for) an object's having four sides that it is a square. Or, again, it is sufficient for your having something to drink that you have a glass of Coca-Cola®. http://www.sfu.ca/philosophy/swartz/conditions1.htm --------------------------------- Definition: A necessary condition for some state of affairs S is a condition that must be satisfied in order for S to obtain. For example, a necessary condition for getting an A in this course is that a student hand in a term paper. This means that if a student does not hand in a term paper, then a student will not get an A, or, equivalently, if a student gets an A, then a student hands in a term paper. Definition: A sufficient condition for some state of affairs S is a condition that, if satisfied, guarantees that S obtains. For example, a sufficient condition for getting an A in this course is getting an A on every piece of graded work in the course. This means that if a student gets an A on every piece of graded work in the course, then the student gets an A. Handing in a term paper is not a sufficient condition for getting an A in the course. It is possible to hand in a term paper and not to get an A in the course. Getting an A on every piece of graded work is not a necessary condition for getting an A in the course. It is possible to get an A in the course even though one fails to get an A on some piece of graded work. http://philosophy.wisc.edu/hausman/104/nec-suf.htm ------------------------------ A handy tool in the search for precise definitions is the specification of necessary and/or sufficient conditions for the application of a term, the use of a concept, or the occurrence of some phenomenon or event. For example, without water and oxygen, there would be no human life; hence these things are necessary conditions for the existence of human beings. Cockneys, according to the traditional definition, are all and only those born within the sound of the Bow Bells. Hence birth within the specified area is both a necessary and a sufficient condition for being a Cockney. Like other fundamental concepts, the concepts of necessary and sufficient conditions cannot be readily specified in other terms. This article shows how elusive the quest is for a definition of the terms "necessary" and "sufficient", indicating the existence of systematic ambiguity in the concepts of necessary and sufficient conditions. It also shows the connection between puzzles over this issue and troublesome issues surrounding the word "if" and its use in conditional sentences. 1. Philosophy and Conditions 2. The Standard Theory: Truth-functions and Symmetry 3. Further Problems for the Standard Theory 4. Inferences, Reasons for Thinking and Reasons Why 5. Modest Conclusion http://plato.stanford.edu/entries/necessary-sufficient/ --------------------------------- http://www.google.com/search?hl=en&lr=&q=contingency+necessity _______________________________________________ gnu-misc-discuss mailing list [email protected] http://lists.gnu.org/mailman/listinfo/gnu-misc-discuss
