Experimental philosophy is an endeavor at the intersection of psychology and philosophy. In practice, it often looks like a series of surveys asking about hypothetical situations, and asking respondents to agree or disagree that in the situation, the protagonist knows a certain fact, or is conscious, or acted freely, etc. Seen uncharitably, this can look like an attempt to settle philosophical questions by popularity contest.
I don’t think that’s what experimental philosophy does, at least not usually. (I speak no French so I can’t evaluate Giraud’s work.) At a minimum, experimental philosophy can act as a caution against traditional philosophical arguments which rely too glibly on the intuitions of the philosopher at some crucial point in the argument. Such experiments can support a “negative program”, in the words of Knobe and Nichols in the linked article (click on the words “Experimental philosophy” in paragraph one). By showing that the philosopher’s intuitions are not universally shared, they can raise doubts about the traditional arguments.
But I think experimental philosophy can do more than that. It can show how we got to certain “common sense” beliefs which philosophy (often with the help of science) puts into question. By carefully reconstructing the path we have taken, we can see where we went wrong, and precisely which later deductions are thrown into doubt and which are not. If scientific discoveries are involved, of course we have to understand those correctly too. Reconstructing our cognitive-developmental history is psychology. But it is also philosophy, when philosophically important ideas are at stake.
It’s easy to overlook parts of the thought-trail that got us into some “dilemma” and thus misdiagnose our problems. As I’ve argued in my previous posts on free will, free will is traditionally opposed to “determinism” because “determinism” was thought to imply universal causality, where “causality” is a one-way relationship from past events to present and future ones. But this supposed equation between determinism and universal causality is itself a scientific mistake. The traditional “problem of free will” is imaginary, and the traditional “solution” of a nonphysical mind intervening upon physics is an imaginary solution to an imaginary problem.
The “because” in my previous paragraph states a claim about the thought-trail that got us here. It is exactly the kind of claim best evaluated with a large helping of experimental philosophy.
There’s another, less important but still important use for experimental philosophy. Many philosophical problems are about how to reconcile/adapt the “manifest image” to the “scientific image”, to use Wilfrid Sellars’s phrases. In other words, supposing that we understand what science is actually telling us, how best can we state the upshots in everyday language? To know that, we have to understand how people actually use everyday language like “is conscious”, “knows”, and “acted freely”. Just asking them to set down definitions is not a good approach. (Try asking people to define “chair”, and note how few of them allow something like a beanbag chair to count.) But surveying people about hypothetical (preferably not wildly hypothetical) scenarios is a perfectly reasonable approach. If you’re interested in accurate and efficient communication – as everyone who seeks truth is – choosing the right words matters.