Bryan Caplan  

Does Science Need Common Sense?

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Does science need philosophy?  Jason Brennan incisively critiques philosophers' case for the affirmation.  How the "gotcha" works:

A: "Science doesn't need philosophy! Science gets by on its own."
B: "How do you know that the universe is uniform? How do you know that the scientific laws won't just change tomorrow for no reason? How do you know that just because past electrons have all behaved one way that future electrons will behave the same way? How do you know that your experiments aren't modifying the behavior of the things you observe in such a way that makes your conclusions irrelevant for predicting outside behavior? How do you know..."
A: "Well..."
B: "And you're doing philosophy!"
Gotcha! Call this kind of argument the "gotcha!" argument. You ask a person who is skeptical of the value of philosophy a question about science, and she responds by doing philosophy. So, therefore, isn't philosophy valuable?

What's wrong with the argument:

The problem, though, is that the conversation could continue as follows:

B: "Ok, you got me. Those are interesting questions and science itself doesn't really answer them. So, do philosophers have good answers to these questions? Have they solved these problems?"
A: "Well...no, not really. I mean, I think my latest article in Synthese helps, but basically everyone disagrees with me, and pretty much every possible answer to these questions has really good arguments for it and really good arguments against it. Not only do we lack any consensus in philosophy on the interesting questions, but, if I'm honest with myself, it's entirely reasonable for us to lack consensus, because none of the work is compelling enough to deserve widespread acceptance."
B: "Great. I'm going to go back to doing science and just ignoring you. Maybe let us know if you manage to settle anything in the next 2500 years."
A: <sniff>

Reading Jason made me realize that a parallel "gotcha" does work.  Only this time, it's not philosophy mounting the offensive, but common sense.  Here's my revised dialogue:
A: "Science doesn't need common sense! Science gets by on its own."
B: "How do you know that the universe is uniform? How do you know that the scientific laws won't just change tomorrow for no reason? How do you know that just because past electrons have all behaved one way that future electrons will behave the same way? How do you know that your experiments aren't modifying the behavior of the things you observe in such a way that makes your conclusions irrelevant for predicting outside behavior? How do you know..."
A: "Well..."
B: "And you're relying on common sense!"
B: "Ok, you got me. Those are interesting questions and science itself doesn't really answer them. So, does common sense have good answers to these questions? Have they solved these problems?"
A: "Basically.  Common sense affirms all the assumptions science takes for granted: The uniformity of nature.  The stability of causal laws over time.  The existence of the physical world, the validity of sense perception, the reliability of human reason, and so on."
B: "But what about all the common-sense claims science has refuted?"
A: "Science only achieves this by using more fundamental common-sense claims to undermine less fundamental common-sense claims.  For example, the validity of sense perception is a more fundamental common-sense principle than the apparent flatness of the Earth.  So when observations show the Earth is round, the common-sense response is to change our mind about the shape of the Earth, not the validity of the senses.  The same goes for, say, special relativity.  It's weird, but it's what our eyes tell us when we scrupulously measure."
B: <hmm>
More here, here, and here.


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COMMENTS (22 to date)
BH writes:

Science works best with a common sense philosophy. I.e. science needs Aristotle.

David Condon writes:

Falsifiability, Bayesian confirmation, determinism, functionalism, and the Uniformity of Nature are common sense? I'm not so sure about that.

john hare writes:

I've learned to distrust any argument based on common sense. Common sense is an individual perception based on personal experience and frequently invalid when applied outside the scope of the personal history. In my experience, people that claim having common sense often have the least of it. Common sense being an excuse to not think.

"Common sense" and "everybody knows" are a couple of phrases for people with integrity to be wary of. Especially if you are involved in real world problems that have real world consequences. In the concrete work that I do, problems caused by that type people often lead to sweat, jackhammers, and red ink. It's probably not as critical in the ivory tower world.

I am impressed by Bryan Caplan's philosophy.

James writes:

Suppose I want to start using this common sense stuff. How will I be able to tell whether I'm applying it, or just making assertions?

Philo writes:

Sense perception shows only that the curvature of earth is *approximately* zero (which is true), not that it is *exactly* zero, just as sense perception--even using careful measurement--shows only that I am about six feet tall, not that I am *exactly* six feet tall. The claim that the curvature of the earth is *exactly* zero is a *theoretical extension* of common sense.

ChrisA writes:

Yes true skeptics can basically agree on nothing. But scientists and more relevantly engineers can use their insights based on common sense and other axioms to make cool stuff that works and make true predictions about future events. It's not that science is potentially provably true that makes it worthwhile, it's worthwhile because it's useful. If philosophy could be of some practical use I would have no problem with it. But in over three thousand years of debate we don't even have a general theory of when it's ok to lie to take one trivial question.

entirelyuseless writes:

The problem with this is that "doing philosophy" as opposed to "just using common sense" simply means using your common sense as carefully as you can, to come to the most accurate conclusions you can.

Of course, when people try doing this in real life, they often fail miserably, which is why philosophy doesn't "settle" anything. This doesn't change the fact that if common sense is necessary (which it is), then philosophy is necessary.

Matt Skene writes:

You're both selling philosophy short here. Philosophy has established importing findings that scientists routinely ignore. For example, philosophers have shown that logical positivism is false, and yet prominent scientists such as Stephen Hawking call themselves positivists, and data is still routinely interpreted as if positivism is true.

Scientists also frequently speak on issues with a complete lack of awareness of whether or not they're doing science. Virtually every new atheist who has written a book about God has used pathetic and ridiculous arguments in their books and displayed a casual, comfortable ignorance with the history of the field they're trying to write in. Similar things are often true of "discoveries" people put forth about human nature in a number of fields. Philosophers may not have settled answers, but we do know crappy philosophy when we see it, and virtually every scientist engages exclusively in crappy philosophy.

Njnnja writes:

American pragmatism is a well-established school of philosophy in its own right. You should read more about it and become familiar with the last 100 years of philosophical tradition that has shaped the culture and institutions that you live in and are a product of.

I agree that there are not going to be any groundbreaking new discoveries in metaphysics but understanding the history of metaphysics can help us avoid the pitfalls in thought that have occurred from time to time over the last 2500 years. (however, note that ethics has always, and will always, be important since new technologies will pose new moral questions). As long as people are curious and can ask questions (like some of the somewhat snarky, yet totally legit commentators above), having an answer better than "my common sense tells me this is so" can be important.

Jared writes:

Even assuming that you are right about the validity of intuition, how we can know which common sense beliefs are more fundamental than others? Your common sense intuition says that morality is objective. Someone else might have an intuition that God is real. Prove them wrong.

Jared writes:

The problem with common sense is that it's not as common as many would like to believe. God is the perfect example. 300-400 years, everyone believed in God. No one questioned it because it was common sense. Suddenly, some people did and now many people grow up in a secular world where religion can seem bizarre. And it's not that someone used a more "fundamental" intuition to disprove that one, it's simply that people believed that it didn't have the required proof to believe in it, which can be applied to all intuitions.

Daublin writes:

Somewhere in the 20th century, "science" got redefined as being a descriptive study of what scientists do. The people that are "scientists" are then anyone who identifies with that label.

Philosophy has been useful for describing why certain simplistic theories don't accurately describe what real-life scientists are doing. To name two theories that have been shot down by philosophers, consider logical positivism and falsifiability. I'm sad about this, but if you look up the examples, you can see that those older views just don't jive very well if you consider them too closely.

Anyway, I don't find "scientific thinking" an especially useful description of anything any more. If you want to discuss interaction styles and research methods that are likely to yield better knowledge growth, then using the word "science" is likely to throw things off track.

Here a few things to consider about modern-day science:

- The peer-review process is not tempting for people trying to solve technological problems. We no longer live in a world where cross-university collaboration happens via letters and books. If you want to collaborate with someone at another institution, you would pick up the phone, write an email, create a project on github, or many other things that make peer reviewed journals look like complete dinosaurs.
- Prominent scientists are heavily involved and committed to polarized political issues around their topic. This is especially true for macroeconomics, for CO2 controls, and for nutrition and intoxicants. It's like members of the jury are calling witnesses and making speeches to the court; no human being can be good at both of these roles.
- Archival practices are regularly found to be very poor among almost all modern practicing scientists.
- In part because of archival practices, replication attempts have largely failed across a wide number of fields. People are publishing stuff, other people try it, and the effect is not there.
- Most scientists I hear from are completely dismissive of anyone that disagrees with them. Rather than talking about how to make their case more compelling--something as I youth I thought of as part of the scientific method--they spend tremendous energy on identifying dissenters as being non-scientific and therefore possible to just ignore.
- Most scientific conferences I have attended are filled with presentations that many of the other attendees don't believe to be an accurate reflection of what is really working and workable. Maybe it was different in the original Royal Society, but nowadays, professional scientists are by and large good at furthering their career. They get those papers out and they solicit favorable reviews from each other.

Njnnja writes:

@Daublin
Somewhere in the 20th century, "science" got redefined as being a descriptive study of what scientists do.

That pretty much happened here. But the point is a strong one, and I wouldn't say that "science" was redefined in the 20th century, but rather, that it was finally recognized in the 20th century that "science" has always been what is done by scientists in scientific communities.

James writes:

All activities, science included, have underlying philosophical assumptions. The only choices are articulated and defended philosophical assumptions or unarticulated and undefeated philosophical assumptions. Scientists might wish to opt out of this dilemma but no such option exists. Believing that they have such an option is just another example of an unarticulated and undefined philosophical assumption.

RPLong writes:

This argument seems to affirm the consequent: Whenever science proves common sense wrong, it's because science is invoking a superior form of common sense. Great, but how did we figure that out...?

LD Bottorff writes:

When Aristotle said that heavier bodies fall faster, in direct proportion to their weight, common sense said he was right. Scientists in the 16th and 17th century challenged "common sense" and a more consistent theory of gravity developed. Some people didn't like that the scientific view challenged Aristotle or some of the Biblical accounts, but scientist plodded on, challenging existing beliefs, even when the beliefs were supported by "common sense." Common sense tells us that simple systems do not organize themselves into more complex system; just the opposite. Entropy rules! That's the common sense argument against evolution.
We need scientists to challenge common sense. When Paul Krugman proposed New Trade Theory, it challenged the common sense of people who cited various historical examples of how protectionism allowed important industries to grow. To the extent that economists challenge the common sense understanding of our economic system, they are being good scientists. When they re-affirm the popular biases of the day, they are not being good scientists.

Mortadelo writes:

I agree with Ninnja. The whole methodological problem, as well as the concept of truth, is yet solved (i.e. not solved) by pragmatist philosophy. Even Popper's description of scientific method can be expressed in pragmatist terms.

delurking writes:

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bd writes:

The line between science and philosophy is only drawn by doing philosophy.

If anyone disagrees with that claim, I invite them to explain which branch of science is responsible for distinguishing science from philosophy, and on what scientific basis it would do so.

We don't even have a consistently accepted "necessary and sufficient"definition for "science".

We can't even distinguish the various branches of science from one another without resort to philosophical principles.

The "rebuttal" that Brennan offers blames philosophy for not having solved the problems it brings up.

Which is akin to dumping Physics out the window because we haven't resolved Relativity and Quantum Mechanics.

It's true that one can do an enormous amount of Science without doing much heavy thinking in Philosophy. But that's like saying that you can play football without having to know much Physics.

Physics is involved in the playing of football, whether the individual football player knows it or not.

Similarly, you can "shut up and calculate", and refuse to engage in the philosophical discussion. But in doing so, you are relying on the philosophical work of your predecessors who even created the categories you are calculating.

Elias Hakansson writes:

Common sense doesn't do well with quantum physics at all.

Colombo writes:

I beleive that common sense needs philosophy, philosophy needs science, science needs desperately free markets, and free markets need people with enough courage to act as if they were rational, which is close to using common sense but not the same.

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