15.2.8: Aiming to Disconfirm

Last updated
Save as PDF

Page ID: 36297

Bradley H. Dowden
California State University Sacramento

\( \newcommand{\vecs}[1]{\overset { \scriptstyle \rightharpoonup} {\mathbf{#1}} } \) \( \newcommand{\vecd}[1]{\overset{-\!-\!\rightharpoonup}{\vphantom{a}\smash {#1}}} \)\(\newcommand{\id}{\mathrm{id}}\) \( \newcommand{\Span}{\mathrm{span}}\) \( \newcommand{\kernel}{\mathrm{null}\,}\) \( \newcommand{\range}{\mathrm{range}\,}\) \( \newcommand{\RealPart}{\mathrm{Re}}\) \( \newcommand{\ImaginaryPart}{\mathrm{Im}}\) \( \newcommand{\Argument}{\mathrm{Arg}}\) \( \newcommand{\norm}[1]{\| #1 \|}\) \( \newcommand{\inner}[2]{\langle #1, #2 \rangle}\) \( \newcommand{\Span}{\mathrm{span}}\) \(\newcommand{\id}{\mathrm{id}}\) \( \newcommand{\Span}{\mathrm{span}}\) \( \newcommand{\kernel}{\mathrm{null}\,}\) \( \newcommand{\range}{\mathrm{range}\,}\) \( \newcommand{\RealPart}{\mathrm{Re}}\) \( \newcommand{\ImaginaryPart}{\mathrm{Im}}\) \( \newcommand{\Argument}{\mathrm{Arg}}\) \( \newcommand{\norm}[1]{\| #1 \|}\) \( \newcommand{\inner}[2]{\langle #1, #2 \rangle}\) \( \newcommand{\Span}{\mathrm{span}}\)\(\newcommand{\AA}{\unicode[.8,0]{x212B}}\)

In the initial stages of a scientific investigation, when a scientist has an idea or two to try out, it is more important to find evidence in favor of the idea than to spend time looking for disconfirming evidence. However, in the later stages, when a scientist is ready to seriously test the idea, the focus will turn to ways to shoot it down. Confirming evidence—that is, positive evidence or supporting evidence—is simply too easy to find. That is why the scientist designs an experiment to find evidence that would refute the idea if it were false. Scientists want to find the truth, but the good scientist knows that the proper way to determine the truth of some idea is to try to find negative, not positive, evidence. A scientific generalization, at least a universal one of the form "All X are Y," will have all sorts of confirming instances (things that are both X and Y), but it takes just one X that is not Y to refute the whole generalization. So disconfirming evidence is more valuable than confirming evidence at this later stage of scientific investigation. Failure to find the disconfirming evidence is ultimately the confirming evidence.

Although scientific reasoning is not so different from other kinds of logical reasoning, it is special in that its claims tend to be more precise, and the evidence backing up the claims is gathered more systematically. This completes our review of what earlier chapters have said about scientific reasoning. Let's now probe deeper into the mysteries of science.