Science is descriptive, engineering is prescriptive.

More verbosely: Science is about creating knowledge about out how things work, engineering is applying knowledge to make things work.

Engineering is how you build a bridge. Science is how you find out how to tell whether that bridge will hold.

Generally accepted philosophy of science is positivism, which states that 'why' in general is unanswerable and we should satisfy ourselves with descriptions. Therefore science is more about precise descriptions and their predictive power.

it's exactly the reason scientists formulate hypotheses (and null hypotheses), and verify them with observable data.

In short, hypotheses are the key instruments to investigate into unknown(and hopefully, consistent) world.

Scientists generally don't pay much attention to philosophy.

Does that mean mad science is about 'why not'?

:)