#deductivism

[raglanphd]

[distancefromreason]

Sherlock Holmes and logic part 3: Eliminating the impossible

If some of the terms are unfamiliar or unclear to you, I suggest reading part 1 and part 2 of this series.

In what I think is one of the coolest and ingenious theories in the history of philosophy, German philosopher Karl Popper (1902-1994) tried to take messiness of induction out of scientific advancement. He created an account of the scientific method that only used deduction and would therefore not have to hedge its discoveries with probabilities. Induction requires placing a probability on a conclusion’s truth because even if we observe a million ravens and inductively conclude that all ravens are black, a white raven may be born tomorrow.

Popper's theory, often called deductivism, is based off of a simple observation. While we can't prove a general theory like "all ravens are black" with certainty, we can disprove it using logically certain deduction. An albino raven completely annihilates the hypothesis that all ravens are black.

Making negative claims about the world is nice, but we really want positive claims. We want to know what the world is like rather than what it isn't like. We can't bake bread if we only know it doesn't contain cyanide or cell phones. Getting past this limitation—to get from what isn't to what is—requires us to disprove every possible explanation except one. This is an extreme version of Sherlock's maxim: excluding everything else as impossible, the remaining explanation, however improbable, must be true.

If someone manages to eliminate every explanation against one, they successfully made a positive claim about the world without having to rely on induction. It's known with certainty. For deductivism to work, every single theory has to be ruled out. Otherwise, since we haven't ruled everything else out, we might be wrong.

Eliminating every possible explanation turns out to be an impossible proposition. A complete list of explanations would include perfectly plausible explanations next to practically impossible ones. To get to that nice clean certain conclusion, we need to eliminate both pedestrian explanations and once-in-a-million-billion-billion-year quantum events. And good luck coming up with that list. There hasn't been a man alive with the creativity to come with every possible explanation, and as far as we know, there are possible explanations that are incomprehensible to us.

That leaves us in an unsatisfactory position. We can come up and eliminate possibilities our whole lives and never reach the end. Deductivism appears to be impossible, but that doesn't mean Sherlock got the nature of logic wrong. Rather, he deductively eliminated theories in order to narrow down his investigations. All in all, it's pretty solid logic for someone who doesn't know what induction is.

[jezunya]

If you haven't seen this video yet, you really need to. I haven't gotten through it a single time without crying.

By Deductivism / Lurlonde

[fargreencountryswiftsunrise]

the fandoms of tumblr | be brave (by Deductism)

[johnhwatsons]

Just taking time to drop a message in your askbox to say I read your great review of A Scandal in Belgravia. Perfect explanation. I wish I could do the same but I'm just standing there and feeling like sh*t. Keep up the good work for your blog, I spent a lot of time on your blog reading your tags and posts when I discovered it.

Oh, gosh, thank you so very much, darling! ♥

I can't believe people are still reading that review tbqh haha I do worry about it sometimes because it's really quite heavily interpretative of me, somebody could very easily read it, have an entirely different view of the episode and not see or agree with a single thing on there! haha But I'm really glad you enjoyed it!

Oh gosh, honestly, thank you! That means so much when people actually take the time to sort their way through my utter nonsense! ♥

[cytharat]

It's really a pleasure to scroll your tumblr. I think if I were allowed, I would marry your gifs. Sorry, this is kind of stupid. By the way, keep up the good work ! *Instant following*

Oh no, that's not stupid at all! :) my gifs get all kinds of proposals and I think there are also a lot of secret affairs going on, so... please, join the club! :D