Many philosophers in the second half of the 20th century really seemed to think that they were laying the foundations for science by laying down the conceptual (necessary) truths.
Given how long philosophers have been at conceptual analysis (I mean the 20th century stuff), and how many have been doing it, what can we say are the two most important concept results of all that effort?
Theorizing is of course essential to make progress in understanding, but theorizing in the absence of knowing available relevant facts is not very productive.
Studies of decision-making in the monkey, where activity of single neurons in parietal cortex is recorded, you can see a lot about the time-accuracy trade-off in the monkey's decision, and you can see from the neuron's activity at what point in his accumulation of evidence he makes his decision to make a particular movement.
Early studies of sleep and dreaming were crucially dependent on waking subjects up during sleep to find out whether they are dreaming or not. Using that strategy, it was found that when the eyes are rapidly moving (REM sleep) people are usually dreaming; when the eyes are not moving, there may be some mentation, but little in the way of visually rich dreams.
I made the assumption, wrong of course, that conceptual analysis was a brief preliminary on the road to finding out about the nature of free will, consciousness, the self, the origin of values, and so forth.