Odd -- contrary to other users' comments, I don't find this topic silly at all. As I see it, "science" is the ability to predict the future†. That's all. And thus a better prediction corresponds to better science. For instance, quantum electrodynamics has been used to calculate the gyromagnetic ratio of an isolated electron to 10 digits of experimental accuracy. That's incredible. In terms of predictive capability, the order goes: physics > chemistry > biology > psychology. That's not to say that any field is less valuable than any other; it's just that the higher level fields are more complex, and thus it is harder to formulate predictive models for them.

So if the value of science is its predictive capacity, then how does one verify that capacity? Through reproducibility. This property is essential to modern research; all scientific results must be able to be reproduced by anyone (assuming they have the appropriate equipment and the ability to adhere strictly to a specific procedure). For if reproducibility were not a requirement, then science would be of little value.

For some reason, a lot of scientists (or maybe just people on the internet who like the idea of science) pigeonhole themselves into the philosophies of positivism, physicalism, and materialism. I don't know why. I do research in quantum chemistry, and even as I learn more about the subject (and quantum field theory), no increase in knowledge has ever changed my philosophical stance. The only thoughts that run through my mind as I learn more are "Cool, now I can make better predictions" or "Hey, that's kind of elegant that nature works that way".

I find it odd, then, that so many people derive their entire life philosophy from sensory input corresponding to output from other humans. It's weird to me. If one were to plant a microchip that affected optical nerves into the brain of one of these people, and the microchip caused them to see an object that wasn't there, I would hardly be surprised if they denied seeing the object at all once they realized the object's visibility wasn't "reproducible".

Is it really the case that so many believe that what is real is not only what is personally experienced, but what is also supposedly personally experienced (and thus communicated) by others?

Playing devil's advocate, assume the simulation hypothesis (I don't actually believe it, but it's useful to illustrate my point). Furthermore, suppose that each individual human has been fed sensory input that only they are capable of experiencing, but the input is both personally predictable and reproducible. And lastly, the program running the universe does not allow any chain of interactions to exist that would permit the information describing these individual experiences to be transmitted to other humans.

What's wrong with this? Nothing. It's perfectly reasonable that every person in the simulation observes aspects of the universe that are unique to them, and them alone. It meets the "predictive" requirement for science at an individual level, and while it's personally reproducible, it's not consensually reproducible. Does that really make it any less real?

At least for me, I'm confident that physicalism is false. Why? Because if I were to rank everything I am certain about on a scale of most certain to least certain, at the top of the list would be "I am certain that I am experiencing my own existence". I cannot think of anything I am more sure about. Take away my senses (or manipulate them somehow), but as long as my brain is still functioning and I'm conscious, I'm still experiencing. The universe didn't have to be this way. It could have existed almost like it does now, except that all the people in it would have been philosophical zombies. (And perhaps all of you are, which would make me a solipsist, but at least I'm a solipsist that knows I'm not a p-zombie then.)

† My claim that "science is the ability to predict the future" and "better science corresponds to better predictions" is a semantic issue, and a whole debate could center around developing a consensus on good definitions. Wikipedia lists other attributes of the word "science" in addition to predictability. If you don't like my definition, make up a new word and substitute it for "science"; the argument holds regardless.