Answer
Positivism is a term for a specific philosophical claim: that we can only be sure of those things directly perceived by the senses. Under this restriction, only purely empirical categories such as science can be considered to offer truth. According to the positivist, all other categories, such as religion, are by definition impossible to actually know and therefore not meaningfully “true.” The most overt form of this approach is logical positivism, which goes further, claiming that only statements that are empirical or analytic (purely logical) are meaningful. In this way, both positivism and logical positivism seek to “define away” religion and faith by starting from an assumption that such things are either unknowable or insensible.
A famous example of the principle of positivism is found in a popular quote from David Hume, a father of the Enlightenment and of modern positivist thinking. Hume stated, “If we take in our hand any volume—of divinity or school of metaphysics, for instance—let us ask, Does it contain any abstract reasoning concerning quality or number? No. Does it contain any experimental reasoning concerning matter of fact and existence? No. Commit it then to the flames, for it can contain nothing but sophistry and illusion.”
Hume’s quote summarizes the general attitude of positivism: there is no knowable truth in any statement that is not entirely empirical. As it turns out, this remark from Hume also demonstrates the greatest fatal flaw of positivism. Hume’s comment, as quoted above, contains neither quality nor number and has no experimental reasoning. In short, if Hume’s statement is true, then it is itself “nothing but sophistry and illusion.” In literal terms, this means that one has to make a special exception for positivism in order to be a positivist.
In the end, positivism and logical positivism are essentially just word games. They apply prejudice, not reason, in an effort to defend a preconceived conclusion rather than to explain or reveal any actual truth. By their own reasoning, positivist statements are incoherent. At the same time, positivist reasoning is extremely brittle; the positivist approach is so unreasonably narrow that tweaking the definition to avoid self-contradiction results in abandoning the idea entirely.
From a Christian standpoint, positivism fails to describe either reality or human experience. There are some truths that human beings cannot naturally perceive (Hebrews 11:3). To simply reject what we, as limited beings, cannot see, taste, or touch is an unreasonable limitation. We are called upon to use good thinking (Colossians 2:8) and careful examination (2 Corinthians 13:5), not to arrogantly assume that whatever we cannot perceive cannot exist (Job 38:1–4).