Task: I before E except after C
C#: using System;
using System.Collections.Generic;
using System.IO;

namespace IBeforeE {
    class Program {
        static bool IsOppPlausibleWord(string word) {
            if (!word.Contains("c") && word.Contains("ei")) {
                return true;
            }
            if (word.Contains("cie")) {
                return true;
            }
            return false;
        }

        static bool IsPlausibleWord(string word) {
            if (!word.Contains("c") && word.Contains("ie")) {
                return true;
            }
            if (word.Contains("cei")) {
                return true;
            }
            return false;
        }

        static bool IsPlausibleRule(string filename) {
            IEnumerable<string> wordSource = File.ReadLines(filename);
            int trueCount = 0;
            int falseCount = 0;

            foreach (string word in wordSource) {
                if (IsPlausibleWord(word)) {
                    trueCount++;
                }
                else if (IsOppPlausibleWord(word)) {
                    falseCount++;
                }
            }

            Console.WriteLine("Plausible count: {0}", trueCount);
            Console.WriteLine("Implausible count: {0}", falseCount);
            return trueCount > 2 * falseCount;
        }

        static void Main(string[] args) {
            if (IsPlausibleRule("unixdict.txt")) {
                Console.WriteLine("Rule is plausible.");
            }
            else {
                Console.WriteLine("Rule is not plausible.");
            }
        }
    }
}

Python: import urllib.request
import re

PLAUSIBILITY_RATIO = 2

def plausibility_check(comment, x, y):
    print('\n  Checking plausibility of: %s' % comment)
    if x > PLAUSIBILITY_RATIO * y:
        print('    PLAUSIBLE. As we have counts of %i vs %i, a ratio of %4.1f times'
              % (x, y, x / y))
    else:
        if x > y:
            print('    IMPLAUSIBLE. As although we have counts of %i vs %i, a ratio of %4.1f times does not make it plausible'
                  % (x, y, x / y))
        else:
            print('    IMPLAUSIBLE, probably contra-indicated. As we have counts of %i vs %i, a ratio of %4.1f times'
                  % (x, y, x / y))
    return x > PLAUSIBILITY_RATIO * y

def simple_stats(url='http://wiki.puzzlers.org/pub/wordlists/unixdict.txt'):
    words = urllib.request.urlopen(url).read().decode().lower().split()
    cie = len({word for word in words if 'cie' in word})
    cei = len({word for word in words if 'cei' in word})
    not_c_ie = len({word for word in words if re.search(r'(^ie|[^c]ie)', word)})
    not_c_ei = len({word for word in words if re.search(r'(^ei|[^c]ei)', word)})
    return cei, cie, not_c_ie, not_c_ei

def print_result(cei, cie, not_c_ie, not_c_ei):
    if ( plausibility_check('I before E when not preceded by C', not_c_ie, not_c_ei)
         & plausibility_check('E before I when preceded by C', cei, cie) ):
        print('\nOVERALL IT IS PLAUSIBLE!')
    else:
        print('\nOVERALL IT IS IMPLAUSIBLE!')
    print('(To be plausible, one count must exceed another by %i times)' % PLAUSIBILITY_RATIO)

print('Checking plausibility of "I before E except after C":')
print_result(*simple_stats())