The influence of animal or vegetable life on matter is infinitely beyond the range of any scientific inquiry hitherto entered on. Its power of directing the motions of moving particles, in the demonstrated daily miracle of our human free-will, and in the growth of generation after generation of plants from a single seed, are infinitely different from any possible result of the fortuitous concurrence of atoms… Modern biologists were coming once more to the acceptance of something and that was a vital principle.
Given what we know now about the vastly complex and highly improbable processes and structures of organisms—what we have learned since Lord Kelvin about nucleic acids, proteins, evolution, embryology, and so on—and given that there are many mysteries still, such as consciousness and aging, or how to cure or prevent viruses, cancers, or heart disease, for which we still have far too few clues -- this rather metaphorical and poetic view of Lord Kelvin’s is certainly a far more accurate view of the organism, for the time, than any alternative model that posited that the many details and functions of human body, or its origins, could be most accurately modeled by simple equations like those used for Newtonian physics. To the extent vitalism detered biologists from such idiocy vitalism must be considered for its time a triumph. Too bad there were to few similarly good metaphors to deter people from believing in central economic planning or Marx’s “Laws of History.”
Admittedly, the “infinetely different” part is hyperbole, but “vastly different” would have turned out to be fairly accurate.
“Spinoza suggested that we first passively accept a proposition in the course of comprehending it, and only afterward actively disbelieve propositions which are rejected by consideration.”
Whether this view is more accurate than DesCartes’ view depends on whether the belief in question is already commonly accepted. When in the typical situation a typical person Bob says “X is Y, therefore I will perform act A” or “X should be Y, therefore we should perform act A”, Bob is not making a statement about X or Y, he is making a statement about himself. All the truth or reality that is required for Bob to signal his altruism is that it be probable that he believes that X is Y or that X should be Y. The probability of this belief depends far more on what else Bob and his peers believe than it does about the reality or truth of “X is Y”.