In the modern world the Aristotelian view has, with the spread of democracy, tended to predominate. After all, in a democracy the citizens are presumed to be competent to judge what is best for themselves. Experiments aren't needed. Indeed, this conference isn't needed. Of course there are a few problems with accepting these premises even in the matter of private choices by competent individuals.
Many people choose to smoke, abuse alcohol, or snort cocaine.
Consider, the following action, by a presumably competent individual - Jane. We can ascertain her preferences from her choices. She prefers the action and its consequences to abstinence. She may not be able to imagine accurately how she'd feel after a few weeks of having stopped smoking. She might not know how well she would feel.