Both -ic and ical are used as suffixes to form adjectives from nouns. Sometimes the noun itself ends in-'ic' and can be used as an adjective without a suffix or we add' ical' to form the adjective. Magic (noun) Magic (adjective) Magical (adjective). Very often these adjectives mean the same thing, but sometimes they have different meanings. Some language experts say -ic is more specific and -ical is more general. Electric = operated or produced by electricity. Electrical =concerned with electricity
There are no rules to guide you in this and you have to just learn the differences. Economic = relating to the economy, economics, finance. Economical = avoiding waste or extravagance. (economic can also be used for this sense but economical cannot be used when referring to the economy)
Historic= well known or important in history. Historical = about history or having the characteristics of history.