Knowledge doesn't originate from sensory experiences. Instead, it's from the guesses we invented as theories and the "conjecture and criticism" process. Observation helps us choose between existing theories but doesn't generate new ones.
Have you ever wondered how we actually gain knowledge? Traditional empiricism says we derive all our knowledge from sensory experience (observation). However, philosopher Karl Popper and physicist David Deutsch argue exactly the opposite: knowledge starts with guessing.
Imagine a child trying to understand why the sky changes color. They do not wait to collect perfect data. They blurt out a story, guessing that the sky changes color because it has mood swings. Scientists are grown-up children who do the same, just with better tools.
Karl Popper called this creativity phase "conjecture". He thinks all our observations are never theory-free. For instance, before you can say, "I see a table," you need prior theories about space, solidity, language, etc. As Popper put it, "All observation is theory-laden".
David Deutsch pushes it further and says the mind is a "guessing engine". We creatively rearrange, combine, alter, and invent theories to solve problems long before we gather data.
Once a guess exists, we try to break it. We look for contradictions. Observation's fundamental role is to show that some theories are false so we can provoke better ones. We compare it with rival guesses. If two solid conjectures make opposite predictions, we run experiments that force nature to choose. Observation enters as judge, not author. In other words, the role of observation is to choose between existing theories, not to be the source of new ones.
Popper calls this process "conjecture and criticism". First, we guess (conjecture) how things might work. Then, through observation and logical examination (criticism), we find out which guesses don't hold up. This cycle repeats, refining our understanding each time.
Consider theories like heliocentrism, relativity, and quantum mechanics. These ideas were proposed long before any definitive experiments existed. Scientists didn't derive these concepts from sensory experience. They guessed. Experiments later only served as crucial tests to see which theories hold.
Why does this matter? It reminds us that knowledge is inherently uncertain and fallible. Any finite set of observations supports infinitely many incompatible rules, so you cannot logically climb from raw data to a unique law. Therefore, rather than seeking absolute certainty from our senses, we should embrace open criticism and continuous examination.