Does spotting a red tulip confirm that all crows are black?  Yes, but before I try to persuade you this is true, I'll try to explain why that truth is essential to a proper understanding of Relativity, Quantum Mechanics, Evolution, and Anthropogenic Global Warming.

Each of these entities is a theory - a set of related hypotheses built around an organizing principle.  The first three are thoroughly established by evidence.  The last, AGW, is the newest kid on the block, and less secure, but closing fast.

None has been proved, however.  In science, theories are almost never provable, because it's always conceivable that a new observation will emerge tomorrow that renders a theory untenable.  Each of the foregoing theories has been vigorously challenged with observations alleged to invalidate it, but to date, each has survived, either because the observations have been shown consistent with the theory, or because they could be accommodated by minor modifications of the theory that do not destroy its underlying tenets.  Even Newtonian mechanics, superseded by Relativity and Quantum Mechanics, remains valid in almost all circumstances affecting our daily lives.

These theories are strong, however, not because they have been proved but because they have been repeatedly confirmed.  "Confirmation" in science is not the same as proof, nor should it be confused with the concept involved in confirming a hotel reservation, but rather has a different and very specific meaning.  It refers to a piece of evidence that increases the probability that a theory (or hypothesis) is true.  As the evidence accumulates, that probability rises, but never reaches 100 percent except for rare (and usually trivial) theories that are limited to so few situations that every conceivable counter-example can be tested and falsified. 

Even the dramatic Hafele/Keating experiment, showing time to proceed at a different pace on jet airplanes, depending on whether they flew East or West, only confirmed Relativistic principles (albeit powerfully) rather than proved them -

 http://hyperphysics.phy-astr.gsu.edu/HBASE/Relativ/airtim.html.

Armed with the distinction between proof and confirmation, readers may better appreciate the entertaining example of red tulips and the blackness of crows - a relationship philosophers have occasionally quarreled over, usually in a manner more confusing than informative.  It's also fair to warn that not all confirmatory evidence has equal weight; an observation can "confirm" in the strict sense of the word without strengthening a theory by more than an imperceptible amount.  All that is required is that it reduce the number of opportunities for a theory to be proved false.

Are all crows black?  Proving that hypothesis would be daunting (assuming it to be true), but confirmations are easy to come by.  Look out the window the next time you hear a "cawing" sound.  If you see a crow, and it's black, you've added confirmatory evidence to the hypothesis - one fewer crow to observe before you decide they're all black.

Red tulips may strike you as another story.  In fact, though, they are simply one more route to the same conclusion, albeit a more circuitous one. 

The following two propositions are logically equivalent:

(1).  All crows are black.
(2).  All non-black objects are non-crows.

A moment's consideration will show that if either one is true, both must be.  Conversely, if either is false, they must both be false.  Proposition 2 may strike you as unhelpful, but only because it would make far more practical sense to observe the properties of all crows than of all non-black objects.  In reality, though, neither one would be very practical, and the best anyone can say in favor of focusing on crows is that each confirmatory sighting would be a greater step forward than is feasible from observing non-black objects.

Even so, you may not have the pleasure of seeing crows in your neighborhood.  In that case, finding a red tulip will still pave your way toward accepting the hypothesis that all crows are black.  It's only one tiny step, of course, but if you look out the window and also spot a blue convertible, that's an additional step.  Still a ways to go, but at least you've made a good start.

Less frivolously, I hope you and I might save a few red tulips to reward school boards who resist creationist demands to teach that evolution is seriously challengeable because "it's just a theory", and to honor scientists who insist that although we can't prove with certainty we're warming the planet, it might still be prudent to stop using the atmosphere we share with all living things as a global garbage dump - one into which we've already poured 1.8 trillion tons of carbon dioxide and possess enough oil and coal reserves to add trillions more - http://www.nature.com/nature/journal/v458/n7242/full/nature08017.html         http://www.nature.com/nature/journal/v458/n7242/full/nature08019.html