How Do We Know What We Think We Know?

Rene Descartes Etching
Rene Descartes shocked the world by asserting “I think, therefore I am.” In the mid-seventeenth century that was blasphemy! William Holl/

9 May 2018 – In astrophysics school, learning how to distinguish fact from opinion was a big deal.

It’s really, really hard to do astronomical experiments. Let’s face it, before Neil Armstrong stepped, for the first time, on the Moon (known as “Luna” to those who like to call things by their right names), nobody could say for certain that the big bright thing in the night sky wasn’t made of green cheese. Only after going there and stepping on the ground could Armstrong truthfully report: “Yup! Rocks and dust!”

Even then, we had to take his word for it.

Only later on, after he and his buddies brought actual samples back to be analyzed on Earth (“Terra”) could others report: “Yeah, the stuff’s rock.”

Then, the rest of us had to take their word for it!

Before that, we could only look at the Moon. We couldn’t actually go there and touch it. We couldn’t complete the syllogism:

    1. It looks like a rock.
    2. It sounds like a rock.
    3. It smells like a rock.
    4. It feels like a rock.
    5. It tastes like a rock.
    6. Ergo.┬áIt’s a rock!

Before 1969, nobody could get past the first line of the syllogism!

Based on my experience with smart people over the past nearly seventy years, I’ve come to believe that the entire green-cheese thing started out when some person with more brains than money pointed out: “For all we know, the stupid thing’s made of green cheese.”

I Think, Therefore I Am

In that essay I read a long time ago, which somebody told me was written by some guy named Rene Descartes in the seventeenth century, which concluded that the only reason he (the author) was sure of his own existence was because he was asking the question, “Do I exist?” If he didn’t exist, who was asking the question?

That made sense to me, as did the sentence “Cogito ergo sum,” (also attributed to that Descartes character) which, according to what Mr. Foley, my high-school Latin teacher, convinced me the ancient Romans’ babble translates to in English, means “I think, therefore I am.”

It’s easier to believe that all this stuff is true than to invent some goofy conspiracy theory about it’s all having been made up just to make a fool of little old me.

Which leads us to Occam’s Razor.

Occam’s Razor

According to the entry in Wikipedia on Occam’s Razor, the concept was first expounded by “William of Ockham, a Franciscan friar who studied logic in the 14th century.” Often summarized (in Latin) as lex parsimoniae, or “the law of briefness” (again according to that same Wikipedia entry), what it means is: when faced with alternate explanations of anything believe the simplest.

So, when I looked up in the sky from my back yard that day in the mid-1950s, and that cute little neighbor girl tried to convince me that what I saw was a flying saucer, and even claimed that she saw little alien figures looking over the edge, I was unconvinced. It was a lot easier to believe that she was a poor observer, and only imagined the aliens.

When, the next day, I read a newspaper story (Yes, I started reading newspapers about a nanosecond after Miss Shay taught me to read in the first grade.) claiming that what we’d seen was a U.S. Navy weather balloon, my intuitive grasp of Occam’s Razor (That was, of course, long before I’d ever heard of Occam or learned that a razor wasn’t just a thing my father used to scrape hair off his face.) caused me to immediately prefer the newspaper’s explanation to the drivel Nancy Pastorello had shovelled out.

Taken together, these two concepts form the foundation for the philosophy of science. Basically, the only thing I know for certain is that I exist, and the only thing you can be certain of is that you exist (assuming, of course, you actually think, which I have to take your word for). Everything else is conjecture, and I’m only going to accept the simplest of alternative conjectures.

Okay, so, having disposed of the two bedrock principles of the philosophy of science, it’s time to look at how we know what we think we know.

How We Know What We Think We Know

The only thing I (as the only person I’m certain exists) can do is pile up experience upon experience (assuming my memories are valid), interpreting each one according to Occam’s Razor, and fitting them together in a pattern that maximizes coherence, while minimizing the gaps and resolving the greatest number of the remaining inconsistencies.

Of course, I quickly notice that other people end up with patterns that differ from mine in ways that vary from inconsequential to really serious disagreements.

I’ve managed to resolve this dilemma by accepting the following conclusion:

Objective reality isn’t.

At first blush, this sounds like ambiguous nonsense. It isn’t, though. To understand it fully, you have to go out and get a nice, hot cup of coffee (or tea, or Diet Coke, or Red Bull, or anything else that’ll give you a good jolt of caffeine), sit down in a comfortable chair, and spend some time thinking about all the possible ways those three words can be interpreted either singly or in all possible combinations. There are, according to my count, fifteen possible combinations. You’ll find that all of them can be true simultaneously. They also all pass the Occam’s Razor test.

That’s how we know what we think we know.

And, You Thought Global Warming was a BAD Thing?

Ice skaters on the frozen Thames river in 1677

10 March 2017 – ‘Way back in the 1970s, when I was an astophysics graduate student, I was hot on the trail of why solar prominences had the shapes we observe them to have. Being a good little budding scientist, I spent most of my waking hours in the library poring over old research notes from the (at that time barely existing) current solar research, back to the beginning of time. Or, at least to the invention of the telescope.

The fact that solar prominences are closely associated with sunspots led me to studying historical measurements of sunspots. Of course, I quickly ran across two well-known anomalies known as the Maunder and Sporer minima. These were periods in the middle ages when sunspots practically disappeared for decades at a time. Astronomers of the time commented on it, but hadn’t a clue as to why.

The idea that sunspots could disappear for extended periods is not really surprising. The Sun is well known to be a variable star whose surface activity varies on a more-or-less regular 11-year cycle (22 years if you count the fact that the magnetic polarity reverses after every minimum). The idea that any such oscillator can drop out once in a while isn’t hard to swallow.

Besides, when Mommy Nature presents you with an observable fact, it’s best not to doubt the fact, but to ask “Why?” That leads to much more fun research and interesting insights.

More surprising (at the time) was the observed correlation between the Maunder and Sporer minima and a period of anomalously cold temperatures throughout Europe known as the “Little Ice Age.” Interesting effects of the Little Ice Age included the invention of buttons to make winter garments more effective, advances of glaciers in the mountains, ice skating on rivers that previously never froze at all, and the abandonment of Viking settlements in Greenland.

And, crop failures. Can’t forget crop failures! Marie Antoinette’s famous “Let ’em eat cake” faux pas was triggered by consistent failures of the French wheat harvest.

The moral of the Little Ice Age story is:

Global Cooling = BAD

The converse conclusion:

Global Warming = GOOD

seems less well documented. A Medieval Warm Period from about 950-1250 did correlate with fairly active times for European culture. Similarly, the Roman Warm Period (250 BCE – 400 CE) saw the rise of the Roman civilization. So, we can tentatively conclude that global warming is generally NOT bad.

Sunspots as Markers

The reason seeing sunspot minima coincide with cool temperatures was surprising was that at the time astronomers fantasized that sunspots were like clouds that blocked radiation leaving the Sun. Folks assumed that more clouds meant more blocking of radiation, and cooler temperatures on Earth.

Careful measurements quickly put that idea into its grave with a stake through its heart! The reason is another feature of sunspots, which the theory conveniently forgot: they’re surrounded by relatively bright areas (called faculae) that pump out radiation at an enhanced rate. It turns out that the faculae associated with a sunspot easily make up for the dimming effect of the spot itself.

That’s why we carefully measure details before jumping to conclusions!

Anyway, the best solar-output (irradiance) research I was able to find was by Charles Greeley Abbott, who, as Director of the Smithsonian Astrophysical Observatory from 1907 to 1944, assembled an impressive decades-long series of meticulous measurements of the total radiation arriving at Earth from the Sun. He also attempted to correlate these measurements with weather records from various cities.

Blinded by a belief that solar activity (as measured by sunspot numbers) would anticorrelate with solar irradiation and therefore Earthly temperatures, he was dismayed to be unable to make sense of the combined data sets.

By simply throwing out the assumptions, I was quickly able to see that the only correlation in the data was that temperatures more-or-less positively correlated with sunspot numbers and solar irradiation measurements. The resulting hypothesis was that sunspots are a marker for increased output from the Sun’s core. Below a certain level there are no spots. As output increases above the trigger level, sunspots appear and then increase with increasing core output.

The conclusion is that the Little Ice Age corresponded with a long period of reduced solar-core output, and the Maunder and Sporer minima are shorter periods when the core output dropped below the sunspot-trigger level.

So, we can conclude (something astronomers have known for decades if not centuries) that the Sun is a variable star. (The term “solar constant” is an oxymoron.) Second, we can conclude that variations in solar output have a profound affect on Earth’s climate. Those are neither surprising nor in doubt.

We’re also on fairly safe ground to say that (within reason) global warming is a good thing. At least its pretty clearly better than global cooling!