Topics Science

Question Will science be able to explain everything? My philosophy teacher said: for in order to explain something, whatever it is, we need to invoke something else. But what explains the second thing? What explains the law of gravity itself? Why do all bodies exert a gravitational force on each other? Since nothing can explain itself it follows that at least some of these laws (in the future) will themselves remain unexplained to infinity..., in other words, unexplained explainers? Is that just the way the cookie crumbles?

Accepted:
August 27, 2008

Comments

Yes.

Here is a longer, more nuanced answer:

Any explanation of one fact must be by another fact, as your teacher said. So a regress
is launched: A is explained by B, which is explained by C, which is explained by D,
which... . How is this regress to end? There are only a few options.

One apparent possibility is that it goes in a big circle. But that is not possible: if D
is explained by A, then A would ultimately be explained by itself! That cannot be, just
as you said.

Another apparent possibility is that the regress goes on forever, with different facts at
every stage: D is explained by E, and E is explained by F, and so forth infinitely. I
don't know of any argument showing this to be impossible. On this option, there are no
fundamental laws of nature. Rather, for every law, there is an explanation involving a
more basic law. This picture is rather disappointing, I guess, but so is the fact that
the Yankees are playing lousy baseball this year. Disappointing things happen. (I must
somehow get over that!)

Another apparent possibility is that the fundamental laws of nature could not have been
different from the way they are, so although there are no laws more basic than they to
explain why they hold, there is an answer to why they hold rather than some alternative
laws -- because any alternative is impossible. But it is difficult to see why this would
be.

It *might* in fact be the case that were the values of the fundamental constants in the
laws a wee bit different from what they actually are, then to apply those amended laws,
one must divide by zero or deal with probabilities greater than 100% or some other
mathematical nonsense. In that case, the laws could not be of the same form but with
different values of the fundamental constants. But this argument fails to rule out as
impossible some fundamental laws of a vastly different form. So we still have no answer
to why those very different laws don't hold instead of the actual laws.

The only other apparent option is that there are some unexplained explainers --
fundamental laws that could have been otherwise, but there is no reason why they are not
other than they are.

A final thought: Some have argued that had the fundamental laws of nature been a bit
different from the way they are (e.g., had the strong nuclear force been a bit weaker
relative to electromagnetism than it actually is), then intelligent life like ourselves
could not have formed (e.g., nuclei larger than hydrogen would not have been stable -- so
much for organic chemistry!) -- so that is why the universe that we see is a universe
where the fundamental laws are no different from the way they actually are. The trouble
with this "anthropic" explanation is that even if it explains why *we see around us* a
universe with the actual fundamental laws of nature, it fails to explain why *there is* a
universe with those laws.

A final final thought: Another suggestion is that we do not need to explain why the
actual fundamental laws obtain rather than some alternative set of laws, because in fact,
both sets obtain ... but in different universes! In other words, the suggestion is that
every possible universe exists (though we, here in our universe, can never see or
otherwise detect other universes). Although this would nicely explain why one set of
fundamental laws instead of another rules (namely, because the other set *does* rule --
in another universe), it would not explain why every possible universe exists rather than
only some possible universes (or only one possible universe).