People typically talk about scientific progress. But what does scientific progress amount to? In the philosophy of science literature, one can find three major accounts (See Darrell Rowbottom and Alexander Bird). The Epistemic (knowledge) view holds that people’s concept of scientific progress involves the accumulation of scientific knowledge. The Semantic (truth) view says that scientific progress involves the accumulation of true scientific beliefs, though not necessarily scientific knowledge. The Functional-Internalist (goal) view states that scientific progress primarily involves achieving either theoretical or technological scientific goals. When arguing for or against these three views, philosophers often rely on intuitions about how much progress people think scientists have made in hypothetical cases relative to the amount of knowledge, truth, or problem-solving outcomes that are generated. Typically, these philosophers assume that ordinary intuitions regarding these factors count as some of the best evidence for their particular approaches. But we might wonder: do actual ordinary intuitions best support the epistemic, semantic, or functional-internalist views?
To find out, Wesley Buckwalter and I ran the following 2x2x2 between-subjects experiment.
We wanted to know if people’s actual intuitions about scientific progress differ depending on the particular types of goals scientists may have [technological (working with “electronic circuit boards”) or theoretical (working with “the Theory of Relativity”)]. We also wanted to know whether or not people thought it mattered if the discoveries the scientists made in our vignettes were justified, since this is the essential difference between the epistemic and the semantic views of scientific progress. To capture the two senses of justification discussed in the literature, we constructed vignettes with and without internal justification, as well as with and without external justification (Download Progress_Survey_Materials). Here is an example of one of the eight possible cases that resulted, involving a group of scientists whose goal is to make technological progress and where the relevant discovery is not internally or externally justified:
A group of scientists at the Institute for Advanced Study has been studying the speed of light. Working with electronic circuit boards, the scientists were trying to find particles that travel faster than light. One day, during an anomalous power surge, the computer program the scientists were using managed to physically accelerate the particles in the circuit boards to speeds faster than that of light. As it turns out, the circuit boards work perfectly, and these faster-than-light particles, called “tachyons,” really were being accelerated. The scientists reviewed the logs immediately, but they could not figure out how the program performed the acceleration.
Then, in a contrasting condition, the scientists were given an internal justification, simply by replacing the last sentence of the case above with:
The scientists reviewed the logs immediately, and they figured out how the program performed the acceleration.
In both cases, the scientific belief that is justified (either internally or externally) or unjustified is that there are particles (namely, tachyons) that can travel faster than light.
After reading just one of these vignettes, participants were then asked, the following question:
On a 7-point scale, 1 meaning “no progress” and 7 meaning “enormous progress,” how much scientific progress has been made in the story above?
We found that when the scientists were justified internally, participants were much more likely to attribute scientific progress (M=6.00, SD=1.21) than when they lacked any justification (M=4.58, SD=1.56).
While this is only 2 of the 8 different combinations of cases given, this tendency was indicative of our general finding. The main result of the study was that internal justification had a large impact on people’s judgments about scientific progress despite having or lacking external justification, or having different types of scientific goals. Alternatively, external justification and goal of discovery seemed to make only a marginal impact on participants’ judgments (in fact the only impact goal type had was an interaction whereby the effect of internal justification was slightly smaller in theoretical cases):
We’re curious to know what people think about these results. Pace the semantic view of scientific progress mentioned above, it seems like these data are suggesting that internal justification actually plays quite a large role in ordinary judgments about scientific progress. Similarly, while the degree of the effect internal justification had on progress was influenced slightly by the nature of the scientific goal under consideration, results also seem to show that people don’t really care too much about the two types of goals scientists had in particular, so long as internal justification is present.
Of course, these data do not tell us what role justification is really playing in the actual practices of the natural sciences leading to progress, but we do think they may suggest that justification is an important part of ordinary judgments concerning the concept of scientific progress philosophers of science are discussing.
 A multiple-way between-subjects analysis of variance was conducted to evaluate the effect of internal justification, external justification, and scientific goal on participants’ judgments about scientific progress. We found a main effect for internal justification F (1,389) = 67.34, p <.01, but were not able to detect a main effect for external justification F (1, 389) = .15, p =.699. We also detected an interaction effect between internal justification and scientific goal, F (1,389) = 4.86, p < .05.