using System;

using System.Collections.Generic;

using System.Linq;

​

public class Program

{

    public static void Main()

    {

        RunTest(new List<Object>{1, 2, 3, 4}, typeof (List<int>));

        RunTest(new List<Object>{"1", "2", "3", "4"}, typeof (List<int>), performConversion: true);

    }

​

    public static void RunTest(List<object> objects, Type type, bool performConversion = false)

    {

        var convertedList = ConvertList(objects, type, performConversion);

        Console.WriteLine(convertedList.GetType().Name);

        Console.WriteLine(convertedList.GetType().GetGenericArguments().First().Name);

    }

​

    public static object ConvertList(List<object> items, Type type, bool performConversion = false)

    {

        var containedType = type.GenericTypeArguments.First();

        var enumerableType = typeof (System.Linq.Enumerable);

        var castMethod = enumerableType.GetMethod("Cast").MakeGenericMethod(containedType);

        var toListMethod = enumerableType.GetMethod("ToList").MakeGenericMethod(containedType);

        IEnumerable<object> itemsToCast;

        if (performConversion)

        {

            itemsToCast = items.Select(item => Convert.ChangeType(item, containedType));

        }

        else

        {

            itemsToCast = items;

        }

​

        var castedItems = castMethod.Invoke(null, new[]{itemsToCast});

        return toListMethod.Invoke(null, new[]{castedItems});

    }

}