Could Vs Would

I think this issue has been covered elsewhere in the forum, but here's the basic difference between could and would:

When paired with an "if" statement, "could" indicates possibility:

"If you had finished your dinner, you could have had a piece of cake as well." --> In this instance, you did not finish your dinner. However, the possibility exists that if you had finished your dinner, you would have been allowed to eat cake.

If I had written: "If you had finished your dinner, you would have had a piece of cake as well." then the reader would get the impression that the piece of cake would have been definite, regardless of whether or not you wanted it. This makes it sound like a command or a punishment.

When paired with an "if" statement, "would" indicates something that was certain:

"If you had finished your dinner, I would have given you a piece of cake." --> In this third variation of the sentence above, the narrator is saying for certain that if you had finished your cake, he or she definitively would have given you a piece of cake. Whether you "could" have eaten it after finishing dinner is another story...

Some more examples where this meaning is reflected:

"If I can win the game, you could win it also." --> We're not sure if either one of us will win.

"If I had won the game, I would have been very happy." --> Again, here we're talking in the past tense and saying with certainty that if I had won, I definitely without a doubt would be happy.

Happy studying!

Brett