For example, consider the principle “You can’t make something out of nothing.”
If you wished to defend this principle, would you proceed by conducting an experiment in which you tried to make something out of nothing? In fact, you would not.You would base your defense on our inability to conceive of ever making something out of nothing
Everything we know originates from four sources. The first, our senses, can be thought of as our primary source of information. Two other sources, reason and intuition, are derivative in the sense that they produce new facts from data already supplied to our minds. The fourth source, authority (or “hearsay,” or “testimony” of others), is by nature secondary, and secondhand fact-claims are always more wiggly and difficult to validate. Other sources of knowledge are commonly claimed, and it is not inconceivable that there might exist other sources; but if they do exist, knowledge derived from them is problematic, and careful analysis usually finds that they can be subsumed under one or more of the four known sources and must be seriously questioned as legitimate, separate sources of reliable information. In summary, what is the nature of our knowledge about the real world of objects/events? Our knowledge of reality is composed of ideas our minds have created on the basis of our sensory experience. It is a fabric of knowledge woven by the mind. Knowledge is not given to the mind; nothing is “poured” into it. Rather, the mind manufactures perceptions, concepts, ideas, beliefs, and so forth and holds them as working hypotheses about external reality. Every idea is a (subjective) working model that