Obvious wrongness of Aristotle

Question

Why did nobody notice the empirical wrongness of Aristotle's physics in the parts where possible in his time? It was held, for example, that a flying spear moves strongly horizontally and then falls strongly vertically. Hadn't anyone witnessed the flying and falling of a spear?

Answer 1

Aristotle maintained that women have fewer teeth than men; although he was twice married, it never occurred to him to verify this statement by examining his wives’ mouths. He said also that children will be healthier if conceived when the wind is in the north. One gathers that the two Mrs Aristotles both had to run out and look at the weathercock every evening before going to bed. He states that a man bitten by a mad dog will not go mad, but any other animal will (Hist. An., 704a); that the bite of the shrewmouse is dangerous to horses, especially if the mouse is pregnant (ibid., 604b); that elephants suffering from insomnia can be cured by rubbing their shoulders with salt, olive-oil, and warm water (ibid., 605a); and so on and so on. Nevertheless, classical dons, who have never observed any animal except the cat and the dog, continue to praise Aristotle for his fidelity to observation.

-- Bertrand Russell, The Impact of Science on Society

It's a lesson in trust in authority and received wisdom. It doesn't matter how prestigious someone may be. They may still be wrong, and we should check their work, and there is an unfortunate human tendency not to do so, for fear of being labeled a contrarian.

By uncritically agreeing with what someone prestigious said, we seem prestigious ourselves, and ingratiate ourselves into the community of other people doing the same.

The cure is to embrace empirical observation, to test propositions in impersonal, objective ways, and to rely on what makes sense to your individual sense of reason as opposed to saying what would gain you acceptance and prestige in a community.

Not a very popular cure, even today.

Answer 2

In my humble opinion, Aristotle has been unfairly attacked in introductory science textbooks as a representative of dogma and careless unfounded beliefs. This is the probable reason for your hunch that most of his ideas were "obviously wrong".

As the great Carlo Rovelli says:

Aristotelian physics is a correct and non-intuitive approximation of Newtonian physics in the suitable domain (motion in fluids), in the same technical sense in which Newton theory is an approximation of Einstein's theory. Aristotelian physics lasted long not because it became dogma, but because it is a very good empirically grounded theory.

Since your question is mainly about motion, please allow me to quote relevant information that I have mentioned in another question:

Aristotle (384 BC – 322 BC), a pioneering, iconoclastic, and brilliant ancient Greek philosopher, made the observation in his writings that the long term stable state of objects is at rest, that motion needs a cause to make it happen, and that continuous motion needs a continuous cause. He further observed that the cause should itself be in motion for it to induce motion: a stationary object cannot induce another to move.

He extended this line of deduction further by arguing that since all observed motion in nature is required to be induced by a cause which itself is in motion, there must be a primordial "unmoved mover" which must be the seed cause behind all the subsequent motion. He drew parallels between the concept of the unmoved mover, "active intellect", and God.

There is absolutely nothing wrong in these observations for almost all of the terrestrial motion experienced by humans, except the motion of falling objects which seems to be caused by an unmoving Earth, and the motion of living things which seem to move of their own will without being caused by another moving object.

Even for these outliers, Aristotle developed elaborate ideas to explain their motion.

Regarding the motion of spear which you have quoted, the answer of Ioannis Paizis beautifully explains the nuance in Aristotle's philosophy (special thanks to them for actual quotes).

Further Reading: Aristotle's Physics: a Physicist's Look

Answer 3

If I'm not wrong, it was held, for example, that a flying spear moves strongly horizontally and then falls strongly vertically.

Indeed, you are wrong.

Obviously his explanation of movement (in modern terms) is wrong, but goes like this: whatever moves, moves because of something acting upon it. When the arrow was shot, the initial force that shot the arrow, also made the air (around the arrow) to vibrate. That vibration acts upon the arrow so it continues to move. This vibration is passing force through the air to the arrow. But because of power loss, the air loses its power to move the arrow, so the arrow gradually falls to the ground.

In order to understand what exactly is going on, please read https://ikee.lib.auth.gr/record/299287/files/29_Aristotle%20On%20the%20motion%20of%20projectiles.pdf

... a successive transmission of a motive force that gradually diminishes as it is transmitted from a first mover to successive moved movers ...

... αεί ελλάτων η δύναμις του κεινείν εγγίγνηται τω εχομένω (267a8-9) ...

ελλάτων means something that is continuously reduced, becoming smaller.

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etymology:

ἐλάττων, -ων, ἔλαττον: αττικός τύπος του ἐλάσσων (4th-5th bc word for ἐλάσσων)

ελάσσων, -ων, -ον : (λόγιο) μονοτονική γραφή του ἐλάσσων, άλλη μορφή του ελάσσονας, συγκριτικός βαθμός των επιθέτων ολίγος και μικρός. (comparable degree of less and small)

Answer 4

This has been answered better than I ever could. I'd like to just add - If you take as a premise that Aristotle was describing things that he sees, and perhaps is interpreting them wrong because of ancient lack of knowledge.. Why would you assume that his empirical observations were wrong just because someone interpreted his works that way?

Logically speaking (again, assuming Aristotle wasn't bat-dung crazy), one has to assume that the translation was wrong. He wasn't predicting a future event such as a feather and a stone falling from a tower - he was describing what he was seeing.

The same goes for the other examples.

The part that can be attributed to bad science (by which I mean lack of scientific knowledge) is his interpretations of his observations.. Not the observations.

Which makes Bertrand Russell's rant from @causative's answer dumb. I'm not talking about everything Bertrand- just that quote from the answer.

This is more of a lesson in interpretation and context.

Answer 5

Because its untrue. Aristotle got a lot of physics correct. This was the view of Newton who said in his Philosophical Noteboks that "Plato was his friend and Aristotle was his friend". He would not have said this had he thought Aristotelian physics was crazy. He said this because he saw that Aristotle got a lot of important stuff correct.

But Newton also said, "truth was a greater friend", because he could see how he and others could get further alomg that Aristotle did. This has been spectacularly proven by modern physics.

This break with tradition has now turned into a dogma that Aristotle was fundamentally wrong. This is just rubbish.