Here's a breakdown:
The Short Vowel Rule
The core reason is the short vowel rule. This rule states that when a word has a single short vowel sound followed by a single consonant, you double the consonant when adding a suffix that starts with a vowel (like "-ed", "-ing", or "-er").
Examples:
* hop -> hopped
* run -> running
* swim -> swimmer
Why this rule?
* Preserving pronunciation: Doubling the consonant helps to keep the short vowel sound consistent. In "hop" the vowel sound is short and "o" is pronounced as in "hot". Without doubling the "p", the "o" might be pronounced as in "hope", changing the sound.
Exceptions and Irregularities
English is famously unpredictable! There are some verbs where this rule doesn't apply, like:
* love -> loved
* hate -> hated
These words have short vowel sounds, but they don't double the final consonant. This is due to historical reasons and the development of English pronunciation.
More Complexity
* Silent "e" at the end: If a verb ends in a single consonant preceded by a silent "e", you drop the "e" before adding the suffix. This is because the silent "e" already indicates a long vowel sound.
* hope -> hoped
* Double consonants already in the base word: If a word already has a double consonant, you don't double it again.
* drop -> dropped
In conclusion:
The double consonant rule aims to maintain the pronunciation of short vowels in past tense forms and other derived words. It's a quirk of English spelling that reflects the historical development of the language.