Why did Rudolf Carnap believe scientific tests usually provide confirmation rather than absolute proof?

Rudolf Carnap, a prominent figure in logical empiricism, recognized that scientific tests cannot provide absolute proof because experimental evidence does not deductively imply general scientific conclusions.1

For example, even if a large number of experimental reports confirm that metals expand when heated, these observations do not logically guarantee that the next metal tested will behave the same way. Because scientific generalizations extend beyond the finite set of observed instances, they remain open to the possibility of future counterexamples.1

Consequently, Carnap focused on developing a logic of confirmation that treated scientific support as a matter of degree rather than certainty. He sought to define a quantitative function to measure the extent to which evidence supports a hypothesis, ultimately arguing that this degree of confirmation must satisfy the axioms of probability calculus. His approach to inductive logic was thus probabilistic, viewing scientific evidence as a means to increase the probability of a hypothesis rather than to establish it as an absolute, immutable truth.12