Assumptions We Make


In math, we assume and define certain ideas, and, using these assumptions and definitions, build up a system (some may say a language) in which we can study patterns, prove more complicated ideas within the limits of the system, and use our conclusions to describe rules which apply to the system. All people do something similar in their own lives, though perhaps not as rationally or as consciously. We all have a few assumptions that are the pillars for our worldviews, and we build our worldviews on top of these pillars. If anyone begins by selecting pillars that are architecturally unsound, however, the architectural integrity of the worldview built upon them is also questionable. Since our worldviews are what we believe about life, and since what we believe about life directly influences how we live, it is a big deal if our worldviews aren’t sound. In order for our worldviews to be sound, our fundamental assumptions must be sound: the fundamental assumptions we make are therefore of tremendous importance.

But before you try to really understand the points I’m putting forth, you should know a couple things about me: I am a Christian, born and raised in the church. I have (sometimes very fiercely) challenged multiple “core” doctrines of Christianity such as the Trinity, the virgin birth, the inspiration of the Bible, the existence of hell, and so on, and I have come away more or less convinced of their truths. I say this so you know that I don’t believe certain doctrines simply because those doctrines are widely accepted. This also shows that I enjoy investigating and using logical, rational reasoning skills, even with regard to my faith. I am also pursuing a Bachelor’s degree in mathematics at UC Berkeley. Most of the technical terminology I use comes from this background, and many of the ideas I discuss are based on logical concepts used in proving ideas. When I use words like “assumption” or “postulate”, I am talking about statements I do not intend to prove; since this note is about basic assumptions we make as people, I will mostly be talking about fundamental ideas we take for granted in our lives without attempting to prove them.

I hope that background is sufficient to understand this discussion. Now let us continue.

The Assumption that Rationality is Possible

One of the assumptions that nearly every person must make is that he can trust what his brain tells him. We all need to make this assumption in order to have the ability to function normally. If your brain were lying to you, you would have no clue, would you? This is a fundamental assumption that we all make, and I can guarantee most of us have not fully realized we assume this. Those who do realize it probably don’t spend much time thinking about this assumption, since it would drive them insane if they thought about it too much. If your brain is sabotaging you, every interaction you have had in your life may have been completely different than you remember, or may never have occurred (à la The Matrix). It’s truly a frightening thought.

Along with this assumption comes another: that we have the ability to be logical and rational people. If someone is not convinced he can be rational, then he essentially doesn’t trust that what his brain tells him is rational, and he therefore cannot trust his brain in matters pertaining to rationality and logic. Since the only way we know how to determine what is true and what is not is by using logic, anyone who cannot trust his brain to be logical cannot function. So this is a necessary assumption that we all must make in order to function. Now, in certain cases, we need to rely on others to be logical for us. For example, if I were to tell you that the square root of two is an irrational number (that is, it cannot be represented as a quotient of two integers), most of you would have to believe me, since most of you cannot prove that statement in a logical, rational way. Essentially, if we have no working knowledge about a subject, we rely on those who do to tell us what they believe and what they know about it. We act this way not only in matters of cerebral knowledge, but also in matters more important in our lives.

Pitfalls in Human Reasoning

Most of us assume that human rationality and logic is unquestionable, so long as it is applied to a situation correctly. We think that what the majority believes to be rational and logical is unassailably correct: this assumption manifests itself especially in science. For example, over the last decade or so, one of the more widely talked about scientific theories has been global warming. Now, I’m not here to tell you that global warming is wrong (although I don’t personally believe the evidence is conclusive), but rather that the vast majority of us believe global warming is happening only because the scientists and other smart, rational people say so. Your average Joe has very little knowledge of why scientists insist that CO2 is a greenhouse gas, but he believes the scientists anyway, since they “know what they’re doing”. Again, let me be clear: I’m not here to argue about global warming. I’m not a scientist, so I don’t fully understand it. Rather, I’m trying to give an example of an assumption that most people make without realizing it. In fact, we do this with many scientific theories—the atomic theory, the theory of evolution, the theory of relativity, etc.—we accept them without fully understanding the reasoning and evidence behind them.

“Common Sense”: or What Our Heart Tells Us

I’ve found, though, that in matters that are very important to us, we tend to assume our own logic and rationality is without fault and that the experts are incorrect. A perfect example of this occurs during the audition phase of American Idol when embarrassingly poor singers truly believe they are qualified to be the next American Idol. When the judges break the news to them that no, they actually are not good enough for the show, they rant and rave and say all sorts of foul things about the judges’ qualifications and about the judges themselves. Although nearly all of America agrees with the judges’ conclusions, these people are convinced that they can sing: in this case, it doesn’t matter to them what the experts’ opinions are.

I’ve also found (and this might be more applicable to some of you) that when the experts reach a conclusion that seems ridiculous, we dismiss the experts’ conclusions just as easily. For example, the way we measure the size of sets in math has some interesting implications, some of which seem ridiculous. One of these implications is that there is an equal number of positive numbers as of positive even numbers. In other words, if you were to count the numbers 2, 4, 6, 8, … and the numbers 1, 2, 3, 4, …, you would find that you have the same amount of numbers in both. But wait! It gets better! There’s also an equal number of fractions as there is of positive numbers. Let that one rattle around in your head for a while, and you’ll agree with me when I say mathematicians are crazy. Nevertheless, the conclusion is logically sound. If you’re interested in an informal sketch or a formal proof or some motivation for this conclusion, ask me, and I’ll give you one.

Essentially, what I’m trying to do is show that we will trust our own logic above all else. I have many more examples that I could use to further motivate this point, but I think it’s pretty clear. Sometimes, as with science, we will always trust the experts—that is, until they say something that we believe is illogical. Even in this case, we trust our own logic completely, since we’re the ones logically deducing whether the experts are right or wrong.

Changes of the Intellectual Climate

Now, I’m not suggesting we abandon our logic and allow the experts to determine what we think about everything. Although the experts are the experts for a reason, they are humans just like all of us, and they, too, make mistakes and change their opinions. For example (and I’m using science again, since most people assume it implicitly), if you look at what science said about the origins of life in the 1700s–1800s era, it was totally different than the prevailing view today. Another example: if you go back a mere forty years to the 1970s, you would see the majority of scientists believed global cooling was a frightening reality, and we needed to take measures to prevent another ice age (Newsweek’s article on global cooling). Although this was only forty years ago, science has changed its opinion so rapidly and greatly that global cooling seems ludicrous now. Yet another example: as few as eight years ago, scientists predicted the Y2K disaster, which also never happened. But in 1999, people were convinced technology would go haywire, bank accounts would be wiped, etc.

Now, I’m not bashing science—I’m instead saying that scientists are prone to the same mistakes and peer pressure as everyone else. I’ve taken a good amount of physics, and my dad has a Ph.D. in physics (he works with optics and cryogenics), so I hold scientists and their discoveries about the world in high regard. People have reached incredible conclusions that have held up to scrutiny and other discoveries (electricity, for instance) that enable us to live the way we do today. But scientists are not all-knowing, nor are they always right, so to assume that the scientists’ logic and rationality is above reproach is really an appeal to authority, which is a logical fallacy (that is, that fact that the people in authority believe something does not imply that they are correct). Yet as I outlined above, to assume one’s own logic and rationality to be always correct is equally flawed, not to mention arrogant.

The Choice on Logic

Now you as the reader have a choice to make:

  1. You can accept my argument. What I have done is that I have assumed human logic and rationality to be trustworthy and have logically arrived at a contradiction. In logic, this means that the assumption I began with was false, so human logic and rationality, by my argument, are not trustworthy. So by accepting my argument, you agree with me that we need a better pillar for our worldviews than logic.
  2. You can disagree with my argument. If this is the route you take, then you disagree either because you disagree with my method (proof by contradiction) or because you disagree with my logic. Disagreeing with my method is tantamount to disagreeing with logic, so if you disagree with my method, you must agree with my conclusion. In the latter case, you would need to show where my logic is wrong. If you can’t do this, then you are simply attacking logic, which implies you agree with my conclusion.

Choosing a Fundamental Assumption

We can now see that, no matter what choice you made, our fundamental assumption cannot be our own rational, critical thinking, nor the experts’ logical conclusions, since human logic is not guaranteed to be correct (or even completely logical, in the most objective sense). We know, however, that the experts are often correct and that our own logic enables us to make important decisions and answer important questions correctly, so our fundamental assumption must not dismiss logic and its unquestionable usefulness to our lives.

Our fundamental assumption must never be wrong or inconsistent (i.e., human logic is inconsistent because you can logically show that human logic is flawed), and it cannot change radically with culture, as the experts do, since that would lead to it being either sometimes wrong or sometimes inconsistent. Because it is very hard to prove a fundamental assumption is sound beyond a shadow of a doubt, my efforts will focus more on finding an assumption that doesn’t fail any of the criteria I’ve drawn up. So from here on out, when I say an assumption is sound, I really mean that assuming it is not a bad idea, which is slightly different.

Let me explain my requirements for a fundamental assumption so that it’s clear that these aren’t just pulled out of the air.

We need a consistent assumption: if our assumption isn’t consistent, how can the worldview we build from it be consistent? That would be absurd. Therefore, we should definitely ensure our assumption is consistent.

It is clear that to fundamentally assume something that is obviously false is foolish, so our assumption must not be incorrect.

If our assumption changes with culture, it won’t be very effective, since we then will need to define it slightly differently over time, so I submit that any working assumption that changes over time or over culture has a more fundamental form that can stay consistent over both. Consider as an example the different societal norms in different countries and different times. All of them, whether written or unwritten, have various rules and consequences if those rules aren’t followed; however, one culture may commend what another culture punishes. Over 1500 years before Christ, civilizations would go to war and commit genocide relatively frequently, and the kings who led these civilizations to victory would be loved and hailed as conquerors. In this day and age, genocide is deeply frowned upon. Although these societal norms change, the more fundamental rule in society is to preserve order: although one could keep a record of all the changes in accepted behavior, the basis behind what is acceptable and what is not has never changed.

Logic and What?

Logic fails because it is inconsistent (it is inherently contradictory). We cannot completely reject logic, however, because it is a huge part of our lives: we use it daily, if not more often than that. In fact, whenever we use information that we have in order to come up with information that we do not have, we use logic. Every time a conditional sentence (an “if/then” sentence) is used, it is ruled by logic. Every time we speak with someone, we use logic to convey ideas and to receive ideas. Since logic is fundamental to the way we live, our fundamental assumption shouldn’t completely override logic.

For these reasons, I posit that the correct fundamental assumption is the existence of the Christian God. Since it’s not within the scope of this discussion, I’m not going to go into all the reasons that I assume the Christian God instead of, say, one of the gods of Hinduism or the Islamic god. One reason, though, is that of all the religions in the world, Christianity is the only one that I know of in which we don’t need to be works-centric. For every other religion, salvation and favor from the god of the religion is dependent upon the things you do. With Christianity, God comes to us regardless of what we do. This seems more realistic: if our salvation is based on what we do, none of us as imperfect people can possibly live up to the standard set by a perfect god, but if we are worshipping a god who isn’t perfect, how is this god deserving of our worship?

God, Constant and Rational

In any case, from here on out, when I say “God,” I mean the God of Christianity. Unlike science, God will not change his mind, even after eight years or forty years, or ever, since he does not change with culture. Although he does deal slightly differently with different cultures, he is always just, yet merciful; he is completely perfect and holy, yet he still interacts with humans. Moreover, there are multiple places in the Bible where God encourages us to be logical, odd as that may sound. For example, look at Isaiah 1:18–20:

“Come now, let us reason together,” says the LORD. “Though your sins are like scarlet, they shall be as white as snow; though they are red as crimson, they shall be like wool. If you are willing and obedient, you will eat the best from the land; but if you resist and rebel, you will be devoured by the sword.” For the mouth of the LORD has spoken.

Now, I’m not going to go into the theology of the Old Testament, or all of the questions (many of which are good and valid) that people have about how God interacts with the Israelites and other nations. These deserve an answer, but I want to concentrate strictly on why God encourages us to be logical. I will, however, give a bit of context to this passage from Isaiah, since many of you, Christian or not, may not know what’s going on here. The book of Isaiah concentrates on a prophet named Isaiah and his struggle to warn the people of his country about what will happen if they don’t start getting their act together. God (the Lord) is speaking through Isaiah in this passage.

Essentially, God is saying, “There are two options: you can follow what I say, and things will go well, or you can do something else, and things will go badly. Think about it, and decide what you want to do.” According to God, the people to whom he is talking are logical: it is clear that he assumes the people understand his if/then statement (that obedience leads to prosperity, while disobedience leads to destruction)—and if/then statements are dependent upon logic—so by giving them two conditional (if/then) statements, God encourages them to think logically about what they are doing. He doesn’t tell them to abandon logical thinking, but rather he bids them embrace it.

A second example of God encouraging logical reasoning is in Proverbs 27:17:

As iron sharpens iron, so one man sharpens another.

Here the writer compares the interactions between two people with the sharpening of a knife. Have you ever been in a discussion in which someone makes a statement that further confuses everyone because of his/her sheer lack of logic and coherence? It is clear that people cannot learn from this type of illogical reasoning, so this sharpening of other people is possible only through rational thinking.

A third example of God encouraging logical reasoning can be found in all four of the Gospels. Each of these books tells the story of Jesus’ time on earth, and each contains many of his parables. Parables are short, frequently allegorical stories Jesus often uses to make a point about God or the nature of man. Now, if you claim you can understand an allegory without making logical connections to reality or drawing parallels based on shared similarities between characters in the allegory and people in real life, you are lying to yourself. In fact, if you look in Mark 4:1–20, Luke 8:1–15, or Matthew 13:1–23, you can read about Jesus giving a parable, followed by him explaining it logically to his disciples. As Jesus is God’s son and messenger to mankind, his teachings are equivalent to the teachings of God. Through Jesus’ parables, then, God encourages us to be logical.

The God Unchanging

I could offer further proof of God encouraging logic by appealing to Peter’s logically-driven sermon in Acts 2, or by appealing to the rationality and cold logic in the letters that Paul sent to the early churches, but I think the point that God encourages us to be logical beings is clear. It remains to be shown, however, that God does not change from culture to culture, which will require us to delve (for a short time) into Christian theology. Since proving that God is unchanging from one culture to the next is very hard, I will instead show that God does not change throughout time, which implies that God is unchanging in general, with his consistency between cultures being just a specific case of his unchanging nature.

At face value, it seems that God changes drastically from the Old Testament (OT) to the New Testament (NT). For everyone who is unfamiliar with the setup of the Bible, here’s a quick summary. In the OT, God interacts with a particular group of people through a covenant expressed in a collection of laws. In the NT, Jesus comes into the picture, and God begins to interact with everyone through grace, apart from the laws. These seem to be radically different ways of dealing with people, but I posit that God has always interacted with people through grace rather than through the law.

In Genesis, God interacts with Abraham. God tells Abraham to look up into the sky and to count the stars, if he is able. He then tells Abraham that his offspring through his wife Sarah will number as many as the stars. Abraham is not young at this point (about age 80), and Sarah is well past her childbearing years (about age 70). He and Sarah don’t even end up conceiving until he is 99 years old and she is 90 years old, so this promise God gives him is pretty outrageous.

But the Bible says that Abraham “believed the LORD, and he credited it to him as righteousness” (Genesis 15:6). Notice that God does not consider Abraham righteous because of how many times he sacrifices animals (this was the typical way in the OT to absolve oneself of wrongdoing: in fact, according to the Mosaic Law, one must sacrifice animals to be made righteous). Neither is Abraham righteous because of his rigid adherence to any law. Instead, God calls Abraham righteous because Abraham believes God will do what God says he will do. This interaction is through grace, not law, since Abraham’s righteousness comes from his God-given faith and is not based on Abraham’s obedience to any law. Notice that it is God who fuels the whole interaction, and Abraham does nothing to merit God’s favor, since God gives both righteousness and faith (Ephesians 2:8).

About a thousand years later, a man named David was the king of Israel. It is clear that he knew what God desired because he was “a man after [God’s] own heart” (1 Samuel 13:14). David, though, was not a perfect man by any definition of the word. He once slept with the wife of one of his most trusted servants, then had his trusted servant killed so he could marry the trusted servant’s wife. After he did this, a prophet confronted him and told him that what he had done was evil (2 Samuel 11–12). David then realized what he had done, and wrote these words in Psalm 51:16–17:

You do not delight in sacrifice, or I would bring it; you do not take pleasure in burnt offerings. The sacrifices of God are a broken spirit; a broken and contrite heart, O God, you will not despise.

David realizes here that God interacts with him not through law but through grace. That’s why he says that God doesn’t delight in sacrifices or burnt offerings. This interaction is through grace, since the law would have sentenced David to death. If you look in Leviticus 20:10 and Numbers 35:31, David deserves to have died—twice!—but God spares him. Why? Because God has always interacted with people through grace, and David is no exception to this rule.

There are many more illustrations of this principle in the OT, but this should be enough to show that God has always interacted with people through grace and is therefore unchanging throughout time. What’s more, in 1 Samuel 15:29, we see that God “does not lie or change his mind; for he is not a man, that he should change his mind.” The evidence is clear: God has always interacted with us by means of grace, both in the OT and in the NT, so his means of interaction have not changed at all from culture to culture.

God, a Good Fundamental Assumption

We can see now that God meets the requirements for a sound fundamental assumption laid out above. He does not contradict logic, does not change, and is not self-contradictory (if you can find a contradiction in God, let me know). Now some of you who are atheists or agnostics may wonder why I insist on taking as my fundamental assumption something you believe is imaginary or uncertain. I would reply by asking you how you came to the conclusion that God is imaginary. Did you logically deduce it? If so, how do you know you can trust your logic to be correct? I have illustrated exactly why we cannot build our worldviews on the pillar of logic, since human logic, as a fundamental assumption, is flawed. Therefore, if you have logically deduced that God is imaginary, realize that your method of proof is not reliable. Logic does not always generate truth.

I have mostly discussed mostly why God is not a bad fundamental assumption. I would like to explain why God is actually a good fundamental assumption. To do that, I appeal to an image I used several paragraphs ago. Fundamental assumptions are things around which we build our lives, the proverbial pillars we have erected to hold our worldviews. When we think about them in this sense, it is perfectly sensible to make God, who is a perfect being, our fundamental assumption. To do anything else is to cheat ourselves, since basing our lives off of something imperfect is tantamount to using a shaky pillar to support a building. If we support a building with a shaky pillar, we need to be very careful how much weight we put on it: if we put too much on, the pillar will collapse. But if the pillar is perfect, there is no upper bound for how much it can support. We have two options: either this pillar (the Christian God) is imaginary and cannot hold a consistent worldview, or it exists and can hold a consistent worldview. If we begin to build our worldviews on God and they remain consistent, then the second option is the obvious conclusion; otherwise, the first option is clearly true.

I challenge anyone who has not attempted to build his or her worldview on God to see whether he or she can build a consistent worldview with God as the fundamental assumption. After all, if he does exist, he is theoretically the best fundamental assumption, so assuming God may be the best decision you can make.


2 thoughts on “Assumptions We Make

  1. I love this post, Joel. Thanks for putting it up on the blog, but moreover taking the time to write it and edit it. Solid stuff!

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