We can say "ride a bike", "drive a car", why should we say "play the piano" instead of "play a piano"?
Contrary to what is being said by other answerers, there is a real reason for this, and it's not just for musical instruments.
We use the phrasing "play the piano" because the piano isn't technically what is being played - it's the tool by which music is being played.
We see this type of phrase whenever someone uses the tool as a reference to the activity. You "wield the sword" as a swordfighter. You "wield the pen" as an author. You "use the keyboard", you "work the shovel". An alcoholic would "bury themselves in the bottle". An artist would "wield the brush" and a photographer would "wield the camera".
The construction also works with the tool replaced with the... well, the canvas, or whatever equivalent it might be. A farmer would "work the soil", the artist would "work the canvas", and the traveller would "ride the rail".
Actually, you can say "play a piano", it just means something different than "play the piano".
We use the definite article when describing the skill of piano playing:
I started learning to play the piano at six years old.
We use the indefinite article in all the same places as you use it for "ride a bike".
I prefer to play a piano a couple of times before deciding to buy it.
We use the definite article for describing the skill of playing any musical instrument; we don't do that for non-musical instruments. So:
I want to learn to play the piano.
I want to learn to ride a bike.
But also correct are both:
I want to learn to play piano.
I want to learn to ride bikes.
It would be technically correct but very unidiomatic to say:
I want to learn to play pianos. [WRONG]
In "play a piano" the word 'piano' will mean a particular single physical instrument.
In "play the piano" the word 'piano' will mean the whole class of instruments.
Both are valid but with different meanings, so correct usage depends on the intended message.
We use "the" with any named item from a set of items of the same category.
Have you ever taken the redeye from LA to NY? (category: scheduled flights between those hubs)
I always take the express to work in the morning, but coming home I take the 6:15 Local out of 30th Street Station. (category: trains on the schedule)
Do you play the trombone? (category: musical instrument types)
Have you driven the 2015 Mercedes Gelaendewagen? (category: vehicle models or vehicle models from Mercedes)
Have you tried the strawberry cheesecake at that restaurant? (category: desserts served at that restaurant)
I can't wait to try out the iPhone 6. (category: smartphone models)
I've never operated the M841. (category: microscope models made by Leica)
But we would say:
I've never ridden a zebra.
P.S. But we can create a context where "the zebra" would be used:
I've ridden many a four-legged beast: the hippo, the rhino, the onager, and the horse, of course, but never the zebra.
There is no logical reason for the use of "the" + musical instrumement. It is simply an idiomatic matter. Maybe there is French influence, though in French it is "jouer du piano" (to play of the piano; I have never found out how this genitive can be explained; but "du" is a form of the definite article).
As a Grammar rule in AE, when you refer to playing a musical instrument, you usually use the definite article in front of the instrument, though omitting "the" is also possible For example:
He plays the flute/piano/guitar/clarinet, etc.
On the other hand, when you refer to a musical instrument as a unit, you can use the indefinite article. For examples:
I have a piano. There's a guitar on the table.
Interestingly, when you refer to sports or games, you don't use any article such as "He plays tennis/cricket/volleyball, etc.
I'm guessing here, but I think the correct answer is that piano is being used in two different ways.
- "I learnt to see the future" to indicate a specific future.
- "I learnt to build a house" to indicate a generic house.
- "I learnt to speak the language" to indicate a specific language.
- "I learnt to speak a language" to indicate a language without specifying which one.
So if you say
I learnt to play the piano, you're saying that you learnt the skill of playing a specific type of keyboard instrument...
the piano referring to specific knowledge rather than a specific object. The
the is associated with the implied
skill and not with
If referring to the object you end up with
I learnt to repair a piano, communicating that your ability isn't specific to a single particular piano.
I can play the piano = I have a specific skill.
I can play a piano = I can operate any piano.
I can play that piano = I can operate the specific piano being indicated.
Let me know via comment if I've overlooked something.
I was thrown for a loop with this one, because you're right, it's odd.
Reflecting on the examples of musical instruments and the examples Glen O provided such as "wield the sword" or "wield the pen," a common thread amongst all the usages is that they invoke an abstract archetype. For example, "I wield a pen" suggests the use of a physical pen. It might be a very nice pen, but it is replaceable with another pen. "I wield the pen" invokes the archetypal pen which is responsible for shifting nations with its words ("the pen is mightier than the sword" uses the archetypal pen and "sword" in its construction).
The choice to use these words indicates something of the speaker's attitude. If one is impressed with a pianist's skill, one would laud their skill at playing "the piano." However, if one feels that it's a cheesy living not worth the money paid to the pianist, one might say "I don't know why he gets paid so much. All he does is play a piano. Any monkey could do that." The other wordings can work too ("I'm impressed how he plays a piano" / "All he does is play the piano"), but as a general rule, there's a bit more respect involved when one invokes an abstract archetype. We, as English speakers, have simply been trained to always do so with musical instruments.