Nowadays, hardly anyone would oppose the demand for more rationally based medicine--the catchword here being "evidence-based medicine" (EBM). Anyone trying to comply with this demand will be faced with the question of what is meant by "evidence". It would be false to think that rationality is guaranteed by applying the Galilean method of exact induction. Exact induction aims at objective propositions free of subjectivity. Such propositions are regarded as generally valid, or "true". They lead us toward the transcendent platonic "idea", which is by definition beyond our reach. Exact induction enables us to derive representations of a transcendent idea by means of experimental research. These representations may or may not be useful in actuality, for example in medical therapeutic strategies. Strictly speaking, reproducibility, which is generally taken as proof of a given hypothesis, is not equivalent to identity. Identity implies, among other things, simultaneity.