One question is whether empiricism itself can be empirically verified. Michael Lerner:
"Consider its [scientism’s] central belief: ‘That which is real is that which can be verified or falsified by empirical observation.’ The claim sounds tough minded and rational, but what scientific experiment could you perform to prove that it is either true or false?"
Another is whether, although empiricism is indeed a value, there may be other methods and approaches that are also valuable. Sir James Baillie:
"Empiricism is so true that the closer one keeps to it – without becoming an empiricist! – the better. Just as, on the contrary, Idealism is so questionable that the farther one keeps from it – without ceasing to be an idealist! – the truer will one's view of reality be."
Daniel C. Dennett:
"This spell must be broken, and broken now. Those who are religious and believe religion to be the best hope of humankind cannot reasonably expect those of us who are skeptical to refrain from expressing our doubts if they themselves are unwilling to put their convictions under the microscope. ... If the case for their path cannot be made this is something that they themselves should want to know. It is as simple as that. They claim the moral high ground; maybe they deserve it and maybe they don’t. Let’s find out."
In philosophy, it is important to define one's terms precisely, as advised by Caritat, Marquis de Condorcet:
"One of the essentials for any sound philosophy is to produce for every science an exact and precise language in which every symbol represents some well defined and circumscribed idea; and so by rigorous analysis to guarantee that every idea is well defined and circumscribed."
Defining terms enables them to be verified. However, if defined too rigorously, one loses the flavor, subtlety and ambiguity of ideas, as well as the different human perspectives that generate them.
Michael Lerner. The Left Hand of God: Taking Back Our Country from the Religious Right. HarperSanFrancisco, 2006. p. 132.
Sir James Baillie, Reflections on Life and Religion, London: George Allen and Unwin, 1952. p 252-3
Daniel C. Dennett. Breaking the Spell: Religion as a Natural Phenomenon. New York: Penguin Group, 2006. p. 17.
Marie-Jean-Antoine-Nicolas Caritat, Marquis de Condorcet. Sketch for a Historical Picture of the Progress of the Human Mind. (1794) Translated by June Barraclough. Westport, Conn.: Hyperion Press, Inc. 1955. p 44.