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theory to the certainty and the trustworthiness of science 
itself. If it can be clearly proved that the physiological meta- 
physics by its own showing is fatal to the authority and trust- 
worthiness of knowledge itself in all its forms, and especially 
in the processes and the conditions which are essential to 
science, it would seem that a system which had claimed for 
itself, and had seemed to many to be the apotheosis of science, 
has committed theoretical suicide. It is our purpose to show 
this by arguments and illustrations which are open to the 
understanding of any one who is capable of judging of sub- 
jects of this kind, or will be likely to be interested in the 
question. So far as the teachings of this system are con- 
cerned with the authority of and trustworthiness of science, 
they relate to four distinct topics — viz., the process of know- 
ledge , the agent in knowledge, the conditions of knowledge , and 
the sphere of knowledge — whether this last be the finite uni- 
verse or the something more, called the infinite, the absolute, 
or God. 
(1.) We begin with the process of knowledge, because 
science as a process is a form of knowledge which passes into 
a product. It is also, as process and product, one of the 
highest and noblest. Any view of the process which is 
seriously defective in any particular must vitiate our con- 
ceptions of the product by weakening or destroying the 
grounds of our confidence in the structure which it builds for 
us. A fatally defective or inconsistent theory of knowledge 
must be suicidal to science. It is then a matter of funda- 
mental interest to know what the physiological view of know- 
ledge must be according to the theory of the evolutionists, and 
what it is defined to be by themselves. 
We ask, first, what it must be according to the theory of the 
evolutionist ? We answer it must be a phenomenon resulting 
from the differentiation and integration of two preceding 
phenomena less complex than itself. We may not refer to 
a knowing agent as its sole originator, because such an agent 
that exercises the function of certainty and distinguishes it 
may be the object known from itself, the knowing spirit, is an 
inadmissible conception. Evolution recognizes no single agent 
in any process. It requires at least two simpler forms or 
phenomena, i.e ., modes of the unknown and unknowable force. 
These must interact, as seed and sunshine, as the nucleus and 
protoplasm, as nerve-cell or stimulant, in such a way as to 
evolve a tertium quid different from and more complex than 
either. Let us suppose that a phenomenon of this kind, thus 
evoked by its consenting forces, and sustained in being only 
