"Experimental work provides the strongest evidence for scientific realism. This is not because we test hypotheses about entities. It is because entities that in principle cannot be 'observed' are manipulated to produce a new phenomena [sic] and to investigate other aspects of nature."

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If the users don't control the program, the program controls the users. With proprietary software, there is always some entity, the "owner" of the program, that controls the program and through it, exercises power over its users. A nonfree program is a yoke, an instrument of unjust power.

— Richard Stallman