Broken Clocks

Which is better, a clock that is right only once a year, or a clock that is right twice every day?

‘The latter,’ you reply, ‘unquestionably.’

Very good, now attend. I have two clocks: one doesn’t go at all, and the other loses a minute a day: which would you prefer?

‘The losing one,’ you answer, ‘without a doubt.’

Now observe: the one which loses a minute a day has to lose twelve hours, or seven hundred and twenty minutes before it is right again, consequently it is only right once in two years, whereas the other is evidently right as often as the time it points to comes round, which happens twice a day.

The losing clock is wrong more often than the broken one. So would you say you prefer the broken clock then?

‘Ah, but,’ you say, ‘what’s the use of its being right twice a day, if I can’t tell when the time comes?’

Why, suppose the clock points to eight o’clock, don’t you see that the clock is right at eight o’clock? Consequently, when eight o’clock comes round your clock is right.

‘Yes, I see that,’ you reply.

Very good, then you’ve contradicted yourself twice: now get out of the difficulty as best you can, and don’t contradict yourself again if you can help it.

You might go on to ask, ‘How am I to know when eight o’clock does come? My clock will not tell me.’

Be patient: you know that when eight o’clock comes your clock is right, very good; then your rule is this: keep your eye fixed on your clock, and the very moment it is right it will be eight o’clock.

‘But—,’ you say.

There, that’ll do; the more you argue the farther you get from the point, so it will be as well to stop.

This amusing discourse was written by the English author and logician Lewis Carroll. (And I grabbed it from here.)

Advertisements

2 responses to “Broken Clocks

  1. CK

    The clock that loses a minute a day is still correct twice a day. It just isn’t correct the same time two days in a row.
    However the correct answer to your question: “Which would you prefer?” Is neither.
    Nothing important happens until you arrive, so the “correct” time is irrelevant.

    • Zim

      “The clock that loses a minute a day is still correct twice a day. It just isn’t correct the same time two days in a row.” Wrong. If it started loosing a minute the day before then it won’t be correct the next day at any given time. it will be correct for the first time in (calculate for yourself, but it takes a while).

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s

Enter your email address to subscribe to this blog and receive notifications of new posts by email.

Join 66 other followers

On Twitter

Categories

%d bloggers like this: