The debate on the Real Presence can be fairly easily settled with the most basic laws of logic. These laws are:
The law of identity.
The law of non-contradiction.
The law of excluded middle.
The law of identity basically states X = X. A thing is synonymous with itself, and distinct from everything else. It is what it is, it is not what it is not.
The law of non-contradiction states that two opposing statements cannot be true in the same sense and at the same time.
The law of excluded middle states that either a statement is true, or its negation is true.
The doctrine of the Real Presence contradicts all three of these laws.
Since we have eyes, we do not actually need to go to scripture to know that the Real Presence is a myth. Every Catholic who has ever consumed the Eucharist knows that it is not real human flesh and blood. That emperor has no clothes. But just because we don't need a scripture to tell us this does not mean we can't have any. And as it happens, we do. First, in 1 Corinthians 11:27, ironically a verse Catholics often misquote to support the Real Presence, we read "Therefore whoever eats this bread or drinks this cup of the Lord in an unworthy manner will be guilty of the body and blood of the Lord."
Whoever eats this what? This chopped human liver? This roasted human thigh? This manwich? No, whoever eats this bread. And we see this throughout the whole passage, as well as the Gospel account Paul refers to. In these same accounts, Christ Himself says "I will not drink of this fruit of the vine from now on until that day when I drink it new with you in My Father’s kingdom." (Matthew 26:29 cf. Mark 14:25; Luke 22:18).
So, if you ever had any trouble believing your own eyes, here you have divinely inspired scriptures telling you that what is consumed at communion is, in fact, bread, and the fruit of the vine.
The law of identity states that a thing is identical with itself. A piece of bread is precisely that: A piece of bread. It is not human flesh. Wine is wine, it is not human blood. Therefore, to claim "no, this is the flesh and blood of Jesus Christ" is a direct violation of the first law of logic.
The law of non-contradiction states that two opposing statements cannot be true at the same time and in the same sense. If the bread is literally bread, it cannot also be literally the flesh of Jesus. If the wine is literally the fruit of the vine, it cannot also be literally Christ's blood. To say it is literally both is a direct violation of the second law of logic.
The law of excluded middle states that either a statement is true, or its negation is true. If "this is merely bread" is a true statement, "this is not merely bread" cannot be. If "this is the fruit of the vine" is a true statement, "this is not the fruit of the vine" is not a true statement. By the first law, "this is merely bread and the fruit of the vine" is a true statement. Therefore, all negations of this statement, including the Real Presence, are direct violations of the third law of logic.
We see, then, that the Real Presence is an illogical, and therefore incorrect interpretation of Holy Communion. Taking "this is my body" literally can only work if you do not take "this bread" and "this fruit of the vine" literally. But why would we take our actual observation to be the metaphor? Based purely on logic, the Real Presence is an invalid interpretation of scripture.