It can be abductively proved. Maybe somebody should take the trouble to do so as a graduate thesis.
It may or may not be a statement of philosophical faith, but it is a statement of methodology. There is no way to demonstrate or research the contrary to this position. How would you go about demonstrating that there can be no physical explanation for a phenomenon? Can you give me an example where this has been demonstrated?
How many times a day do we hear this? Just wait, eventually, sooner or later, some day, all of biology will be explained by means of physical causes, and physical causes alone!
Fortunately, not all scientists are willing to hold their breath while they wait for this grand culmination to occur. Here's Dr. Grandpierre's view of the matter:
"When physics applies the maxim of ignorance, and ignores biological inputs to fit the closure thesis, it misses the main point of the problem. Moreover, the physicalist dogma that 'one day we will be able to determine the actual behavior of living organisms by exclusively physical methods when all the physical details of the most complex organisms of the universe will be clarified' merely postpones the aim to solve the scientific questions of biology by plausible and simple scientific methods to an indeterminately distant future. We find this attitude as decelerating the development of science. Referring to the 'impenetrable complexity' instead of real explanation does not seem to differ from the methods of the 'occult sciences' -- since it plays the role of a Jolly Joker at all places where we need scientific explanations instead."
He also writes this, so very germane to our present discussion:
"The tricky machinery of life is not contained in the laws of thermodynamics. And it is just this tricky machinery that contains the large amount of information necessary for life. Berkovich notes: 'The functioning of living systems has little to do with physics and chemistry. It is a problem of information control' (Berkovich, 2003, 2). This implies the ability of biological information to direct the behavior of cells utilizing the smallest amount of energy. All living systems manifest energy transformations from numerous microscopic motions converging into macroscopic behavior, e.g., as when we write with our hand (Elitzur, 2004). The control processes of living systems act at the molecular scale (Dolev, Elitzur, 1998). Moreover, thermodynamic state functions are macroscopic at the global level of the system; therefore they cannot determine the complex behavior of the cells and of individual molecules. But if there is a relation between energy and manifested biological information, then the astronomical amount of information present in living organisms still needs thermodynamically significant energies to become effective, and so thermodynamics can be really efficient in the study of the nature of life."
When you consider that the human organism is made up of roughly 6*1013 cells, and in each cell more than 105 chemical reactions occur per second, which generally involve localized, "neighbor relations"; and yet the living system is able to organize and integrate all of its astronomically large number of parts distributed throughout its physical extent into one single, dynamic, self-organizing, sensitively-responsive global whole -- well, you've got to figure an enormous amount of information is required. And "information" does not appear to be a physical quantity.