It appears that the word “science” is used in a few different meanings:

  1. A method for determining what is true: perfoming experiments, keeping an open mind, trying not to fool yourself, etc.
  2. The set of facts determined via such methods.
  3. “Science is what scientists do” or “science is what scientists believe” — the set of things commonly believed by scientists.

As for (1), it is the most valuable way we have of finding things that are true. If something disagrees with experiment it is wrong. And if something can be determined or demonstrated by experiment, it does not require any testimony of prior experts or appeal to authority; you can find out the truth for yourself. It is also difficult. In general, the more things we can bring under its purview the better, because our knowledge will become more certain.

For (2), note that it is necessarily always incomplete. Science is definitely not “finished”, as it is said some physicists thought at some point. Also, as said above, science is hard, and subtle. There are entire areas that would be valid objects for science, but for which we have not yet figured out the right experiments to run: either we’re not sure how to measure, how to exclude other variables, our methods of measurement aren’t good enough, etc. Nevertheless, the set we do have is extremely valuable, and the hope is that it will grow.

Another point: someone may determine something through “science” (1), without it becoming part of the mainstream scientific knowledge. Mendel’s experiments were not known or accepted for a while, etc. Someone may not publish. A bunch of people may have done the experiments and arrived at some knowledge, but others are still sceptical as they haven’t done the experiments themselves (either it’s too hard or they haven’t bothered to).

For (3), scientists are human too (read a few dozen posts on Retraction Watch), and there are enough examples of mistaken scientific consensus. (Consider the usual examples: nutrition science, psychology’s replication crisis, Wegener and continental drift.) And again, scientists are human too and there is no doubt a subculture among the tribe of professional scientists, which comes with its own ingroup and outgroup markers, shared beliefs, etc., not all of which may be strictly scientific in the sense of (1) or (2). So when “scientists say…” or even “science says”, it’s important to be clear whether it’s (2) or (3).

Also (conversely?), we shouldn’t use the fallibility of (3) to give up our respect and trust of (2) (as incomplete as it may be) and especially of (1). (More generally, beware of shifting meanings and “motte and bailey”—the authority/flaws of one shouldn’t be used to impugn the same for another.)

Finally, there is “śāstra”, something like systematic study, or scholarship. In the West, only “science” (in some sense) has approached the rigour necessary (and only in recent centuries), so there is a lot of prestige attached to “science” — some of what is admired there actually applies to any (good) śāstra.