00:00:00.000 David Deutsch discovered that Popper's criterion of demarcation, the falsification, was just
00:00:09.640 a special case of a broader phenomenon in epistemology.
00:00:13.920 Many of observed, a claim that is falsifiable does not mean the claim of scientific.
00:00:18.840 For example, if I claim, the world will end June 6, 2026, but a falsifiable claim.
00:00:26.000 If I say cobravenum, Q was heart disease, I've got a testable claim, but is that scientific?
00:00:33.440 Clearly this is not enough to make a claim scientific, but science must deal in evidence.
00:00:40.440 If a thing purports to be science, it is necessary it is falsifiable, but it's just not
00:00:48.040 Popper made a huge leap in discovering falsification.
00:00:54.880 Good explanations are hard to vary, now you can google his TED talk called a new way
00:00:59.280 to explain explanation for this, but it was first hinted at in the fabric of reality.
00:01:05.640 If your favourite, beautiful theory is slain by an ugly fact, then if the theory is
00:01:10.280 any good, you shouldn't be able to just change it a little bit in order to now explain
00:01:16.920 Deutsch, in the fabric of reality, uses the following example.
00:01:21.400 If you think eating a kilogram of grass, Q is the common cold, and someone tries and it
00:01:25.800 doesn't work, so your theory is falsified, then if you come back with, oh, actually it's
00:01:34.480 This is called an ad hoc modification, making your theory easy to vary, and so we can reject
00:01:40.720 the grass, Q is the cold theory, and all infinite variance of it on that basis.
00:01:48.680 And it's fair for us to say, we know that grass doesn't cure the common cold.
00:01:56.600 That we're certain one day someone might come along and show how if you isolate some
00:02:00.280 chemical in the grass and add it to some other chemical in alcohol and take that as
00:02:08.000 No, we can never be sure, but we've no reason to think this is or ever will be the case.
00:02:18.240 True treatments for disease usually come with scientific explanations, mechanisms about
00:02:22.360 cause and effect, they use words invoking viruses or bacteria and how they are deactivated
00:02:32.320 If I say penicillin kills the meningococcal virus or meningococcal bacteria rather, by causing
00:02:38.320 cell walls to burst so that bacteria is killed, it becomes hard to vary in its details.
00:02:44.960 You can look under a microscope and test this theory.
00:02:47.040 You can see that it is indeed penicillin, the chemical and not some other that is involved.
00:02:53.720 You can replace the chemical with something else and you'll find the cure doesn't work
00:02:58.320 And doctors will prescribe just the right amount of penicillin in order to kill meningococcal
00:03:03.080 bacteria in very narrow ranges, too little and it won't work, too much and it might
00:03:11.760 So scientific theories are hard to vary explanations of the physical world and just one
00:03:17.080 feature they have, which is hard to vary, is that they are falsifiable.
00:03:21.240 And when they survive a crucial test comparing them to a rival theory, when they survive
00:03:27.440 that experiment, that other rivals do not, that's an exceedingly hard to vary feature
