340 RAYMOND J. NOGAR 



the kind described by Le Gros Clark — so highly probable that 

 the unbiased, objective observer must be convinced by the 

 convergence of disparate but mutually supporting evidence. 

 No more, no less. This is what a prehistoric fact means to the 

 prehistorian. 



In this sense, evolution is a " fact " as opposed to a mere 

 hypothesis which has not the documentation sufficient to re- 

 move doubt and generate the conviction described. Evolution 

 is a " fact " as opposed to a theory among theories of reputa- 

 tion, as the " steady-state " theory is opposed to the " pul- 

 sating universe " theory in cosmology .^^ Evolution, as defined 

 by Olson, abstracting from the various hypotheses concerning 

 how the process took place, enjoys the status of having no other 

 reasonable natural explanation of the converging evidence to 

 oppose it with sufficient evidential support to produce high 

 probability or conviction. Evolution is a " fact " as opposed to 

 a low degree of probability. On certain levels, e. g. on the level 

 of organic evolution, the degree of probability is high. What the 

 phrase " evolution is a fact " does not mean, however, is that 

 it now enjoys the status of demonstration which generates the 

 certitude of direct observation or inference which follows so 

 necessarily from that observation that it could not be otherwise. 



Thus it is readily seen how the statements of Dobzhansky, 

 Olson, Simpson, Huxley and others at the Darwin Convention, 

 who constantly used the phrase " fact of evolution," were not 

 unequivocally in opposition to the statements made by some 

 philosophers and theologians in their attempts at a dialogue 

 upon common issues. The two quotations from Humani 

 Generis above, for example, assert that evolution has not been 

 fully proved even in the domain of natural sciences and that 

 those transgress liberty of discussion who act as if the origin 

 of the human body from pre-existing and living matter were 

 already completely certain and proved by facts which have 

 been discovered up to now and by reasoning on those facts. 

 It is of capital importance to understand these statements of 



*" EAD, 1, 32-33. 



