This morning, I tweeted a brief critique of Carl Sagan’s famous soliloquy on the pale blue dot:
Carl Sagan famously looked at an image of that "pale blue dot" called earth taken from Voyager 1 and mused about human insignificance in the universe. Sorry, Dr. Sagan, size does not map onto significance. One human life is more valuable than an interstellar nebula.
— Tentative Apologist (@RandalRauser) February 17, 2019
If you’re unfamiliar with this famous rumination, you can listen to it here.
Anyway, I do love Sagan’s writing. He was a masterful science communicator and a true poet as well. That said, the diminutive size of the earth has precisely no metaphysical or atheological import.
However, The Thinker™ challenged me by replying:
“How do you justify your claim?”
I responded with an argument:
- If size determines value then a 10-ton pile of dirt would be more valuable than a 5 lb infant.
- A 10-ton pile of dirt is not more valuable than a 5 lb infant.
- Therefore, size does not determine value.
The Thinker™ replied:
“How do you justify premise 2?”
I replied:
Oh good grief, I hope you never have kids. 
Please note that the emoticon was not that large in the original tweet. For some reason, it became huge after being copy-pasted into this article. But truth be known, this is a serendipitous alteration because the emoticon’s outsized dimensions convey more effectively the depth of my incredulity toward the suggestion that premise 2 needs to be justified.
Think about it like this. Imagine that a dam upriver breaks and a wall of water is rolling toward Smith’s farm. Smith only has time to save the pile of dirt in the back of his pick up truck or the baby in his house. Given that choice, he opts to save the baby. Who would ever ask Smith for his justification in choosing to save the baby over the dirt? Such a question would be absurd.
On the contrary, the justification would only be required in the alternative decision. If Smith had opted to save the pile of dirt instead of the baby, we would demand a justification. But what justification could there be? I’ll leave it to others to answer that question. Suffice it to say, premise 2 needs no justification.
But what then should we think about The Thinker™ and his claim that premise 2 does need justification? Is he arguing in bad faith by presenting skepticism about a premise that he does not, in fact, hold? Or does he really doubt premise 2? I don’t know.
We could try to bring him to reason by presenting him with the Farmer Smith dilemma and asking him what he would do and why. And that might bring him to concede the justification for 2. But what if it didn’t? What if he demanded a reason to think the baby should be saved instead of the dirt? Well, I suppose you could continue to attempt to reason with him.
However, it is also important to take the following lesson: just because you can find a person who is willing to deny the premise of an argument does not mean the argument is not good. Indeed, one can regularly meet unreasonable people who reject a premise in an argument for various reasons. One can also find generally reasonable people who are nonetheless unreasonable within a particular field and that leads them to reject an argument. Either way, for an argument to be a good argument, it needs to be logically valid (i.e. the conclusion needs to follow from the premises) and it needs to have premises that are widely recognized by reasonable people as true or at least highly plausible.
To sum up, don’t ever hang the worth of an argument on its ability to persuade everyone because that rarely if ever happens.
