Last week, we discussed what scientists mean when they say that something exists.
To summarize it briefly: Something exists if it is useful to explain observations.
And this makes, most importantly, no statement about what is real or true which is a question
for philosophers, not for scientists.
I then asked you to tell me whether you think that I exist, because sometimes I am not so
Many of you submitted great answers to my existential question.
I want to pick two of those as examples to illustrate some key points.
Fernando wrote in comment here on YouTube: “When I say “that chair exists”, I am
also fitting the data (collected with my senses) with my internal conceptions of a chair.
I think that the same is true when I see a two dimensional representation of Sabine Hossenfelder
on my computer screen and say that Sabine exists.”
As he says, correctly, he is really just trying to create a model to explain his sensory input.
I am part of a model that works well, therefore he says I exist.
And Dr Castalo wrote in a comment on my blog:
“I believe a single human exists that appears in videos and photographs and authors these
blog posts, tweets, and answers to commentary.
I am aware of no other plausible (to me) explanation for those artifacts and their consistency.”
The important part of this comment is that he emphasizes the explanation that I exist
is plausible, not certain, and it is plausible to him, personally.
In the comments on my blog you then find some exchange about whether it possible that my
videos are generated by an artificial intelligence and I do not exist.
For all you know, that is possible.
But even with the most advanced software presently available, it would be a challenge to fake me.
At the very least, making me up would be a lot of effort for no good reason.
Possible, yes, but not plausible.
The simplest explanation is what most of you probably believe, that I am a human being
not unlike yourself, in an apartment not unlike your own, with a camera and laptop, not unlike
your own, and so on.
And simple explanations are the most useful ones in a computational sense, so these are
the ones scientists go with.
The important points here are the following:
First, explaining sensory input is all you ever do.
You collect data with your senses and try to create a consistent model of the world
that explains this data.
Even scientists and their papers are just sensory input that you use to create a model
of the world.
Second, confidence in existence is gradual.
The only reliable statements about what exists are based on models that you use to explain observations.
But the confidence you have in these models depends on what data you have, and therefore
it can gradually increase or decrease.
The more videos you watch of me, the more confident you will be that I exist.
It’s not either-or.
It’s maybe or probably.
The thing you can be most confident exists is yourself because you cannot explain anything
unless there is a you to explain something.
Data about yourself are the most immediate.
That’s a complicated way of rephrasing what Descartes said: I think, therefore I am.
Third, how confident you are that something exists depends on your personal history.
It depends on your experience and your knowledge.
If we have met and I shook your hand, you will be much more confident that I exist.
Because you only know of one way to create this sensory input.
If you merely see me on a screen, you also have to use knowledge about how your
screen works, how the internet works, how human society works, and what’s the current
status of artificial intelligence and so on.
It’s a more difficult analysis of the data, and you will end up with a lower confidence.
And this is why science communication is so, so important.
Because someone who does not understand how scientists infer the existence of the Higgs
boson from data, and also does not understand how science itself works, will end up with
a low confidence that the Higgs-boson exists and they will begin to question the use of
science in general.
Having settled this, here is the next homework assignment: Does God exist?
Let me know what you think.
And don’t forget to subscribe.