Opinions, facts and theories

megaphoneWe start out in life without any knowledge, but it’s not long before we start forming simple opinions about the world we find ourselves in. We might call these preferences (I like milk). These probably change over time (I like beer) but they are inherently subjective and cannot be exposed to objective scrutiny (my daddy is better than yours), at least not in a meaningful way (no he isn’t.) We think of these preferences as conscious choices, but we are really just observing what we like and don’t like.

Some preferences are commonly shared (being with friends makes me happy) but not universal (I want to be alone.) Some opinions are also widely shared (it is wrong to kill people) but may be subject to change under closer scrutiny (except in self-defence), and even those opinions that seem to be universal are not (the voices in my head said it was OK to kill her.)

It is tempting to propose that certain opinions should be elevated to the status of facts (the sun rises in the east.) Yet often, even these facts need to be modified on closer inspection (the sun doesn’t rise; instead the earth rotates about its axis).

Some facts (that building has 16 windows) are easier to establish than others (the speed of light is 299,792,458 metres per second in a vacuum) but might still be subject to error (is that window really a window, or is it a glass door?)


This can all become very confusing (yes it can) (no it can’t) (I don’t mind.)

Fortunately, there are a few facts that really are true, because they are definitions or tautologies (1 + 1 = 2).


Sometimes when we have a collection of facts, we may be tempted to come up with an explanation for them (fur keeps animals warm) (alien spaceships make crop circles) (everybody hates me.) You’d think this would be hard work, but we do it all the time without even noticing (young people today are lazy and rude) (that guy is a total jerk.) Some explanations are better than others (the sun appears to rise in the east because of the rotation of the earth) and some are really terrible (alien spaceships make crop circles.)


When we have a really good explanation that has been exposed to wide scrutiny and seems to hold together, we can elevate it to the status of a theory (two bodies will attract each other with a force that is directly proportional to the product of their masses and inversely proportional to the square of the distance between them.) A theory combines a wide array of facts together with an explanation of those facts (the apple falls because it is attracted by the earth’s gravitational pull) and also some predictive power (a feather and a hammer will fall at the same speed when dropped on the moon.)


A theory isn’t merely someone’s opinion (evolution is just a theory), but must have broad explanatory and predictive power (both humans and modern day apes are descended from a common ancestor) (we can trace the evolution of species via their DNA), and must be scrutinized and tested very widely (my mummy is an evolutionary biologist) (so is mine.)

A theory can never be perfectly validated (gravity is not a force, but a geometric property of space and time, or spacetime) but failure to invalidate it under a wide range of circumstances puts it on an ever surer footing (two atomic clocks flown around the world in opposite directions were found to disagree with each other by 300 nanoseconds, as predicted by Einstein.) This indicates that there must be some truth behind it, even if it isn’t the whole picture.


A lot of trouble arises when people confuse preferences with opinions, or opinions with facts, or even theories with explanations (no it doesn’t) (yes it does) (you’re a jerk), so I hope that my discussion can help a little.

By the way, I’m not a philosopher (no, I’m not), so I may be completely wrong about all of this (I don’t think I am.) Sorry if you found this boring (I’d rather look at funny photos of cats.)


This post was inspired by the discussion here.


19 responses to “Opinions, facts and theories

  1. Well, in my opinion, this discussion was fascinating. I just want to know where you got a mummy that talks. Oh, and more cat photos please. They make me ridiculously happy- which happens to be a fact.

  2. Great post, Steve. And great examples to distinguish between opinions and facts. The fact that so many people can’t seem to distinguish between facts and opinions drives me nuts. And I go ballistic whenever I hear someone call evolution “just a theory.”

    I have blogged about these matters a number of times. It’s a subject that is near and dear to me, and I wish more people would take the time to distinguish between facts and opinions before passing them along. One post I wrote last August summarizes some of my thoughts on this topic. If you’re interested, you can read it here.

  3. Well, I tried saying it really slowly, and it still didn’t sound like ‘oranges’. So, how am I supposed to believe the rest of this stuff? 😡

  4. In my opinion, this post is awesome!

    BTW, thanks for the link!

  5. Great post. I hope to find something to quibble with later. For now, I’ll just say that the Popeye image was very smoothly incorporated into the flow of your argument. Well done!

  6. Fantastic post. As an almost bona fide philosopher (does a masters count?) I’ll happily sign off on this post. And possibly make it required reading for my students!

  7. Whatever you just said, my opinion is that it was brilliant, well-thought out, and sounded like philosophy. I theorize that a lot of effort went into putting this all together. The fact is that you surprise and impress me with the originality (and good “weirdness”) of your posts sometimes. Oh, and in my opinion, reading your post beats looking at kitten photos. 🙂

  8. Tienzen (Jeh-Tween) Gong

    Steve Morris: “Opinions, facts and theories … {Albert Einstein: “I never said half the crap people said I did”} … A lot of trouble arises when people confuse preferences with opinions, or opinions with facts, or even theories with explanations (no it doesn’t) (yes it does) (you’re a jerk), so I hope that my discussion can help a little.”


    In addition to their own confusions, they make up stories to confuse others.

    Quantum Diaries is an official blog for CERN (the place for the LHC, the largest particle collider in the world). This year is the 100 year anniversary for the publication of General Relativity (GR), it is a time for celebration and is also a time for introspection.

    GR is a great theoretical physics framework which describes a causal universe (the event horizon) and a verified THEORY.

    But, it is also totally wrong to play a (any) part in the final physics theory. Please read a post at (http://www.quantumdiaries.org/2015/03/13/einsteins-most-famous-equation/#comment-1909398622 ) for details.

    Is GR an opinion, a fact or a theory?

    • Tienzen, you’re right. General Relativity is a great example of a theory that has stood the test of time and that has far-reaching explanatory power. But we already know its limits. Somehow we will have to find an even better theory that reconciles GR with quantum theory.

  9. Pingback: In My Pensieve: A Link Round Up | Stories & Soliloquies

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