Category Archives: Philosophy

Larry Laudan. Why Presuming Innocence is Not a Bayesian Prior

“…the presumption (of innocence) is not (or at least should not be) an instruction about whether jurors believe defendant did or did not commit the crime. It is, rather, an instruction about their probative attitudes.”

Error Statistics Philosophy

DSCF3726“Why presuming innocence has nothing to do with assigning low prior probabilities to the proposition that defendant didn’t commit the crime”

by Professor Larry Laudan
Philosopher of Science*

Several of the comments to the July 17 post about the presumption of innocence suppose that jurors are asked to believe, at the outset of a trial, that the defendant did not commit the crime and that they can legitimately convict him if and only if they are eventually persuaded that it is highly likely (pursuant to the prevailing standard of proof) that he did in fact commit it. Failing that, they must find him not guilty. Many contributors here are conjecturing how confident jurors should be at the outset about defendant’s material innocence.

That is a natural enough Bayesian way of formulating the issue but I think it drastically misstates what the presumption of innocence amounts to.  In my view, the…

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Lakatos, Popper, and Feyerabend: Some Personal Reminiscences | Donald Gillies

On 28 February 2011, Donald Gillies presented memories of meeting and working with some of the heroic personalities in philosophy of science, including Karl Popper, Imre Lakatos and Paul Feyerabend. This podcast records his presentation.



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Random Refutations

“(1) Parmenides-Leucippus: Leucippus takes the existence of motion as a partial refutation of Parmenides’s theory that the world is full and motionless. This leads to the theory of ‘atoms and the void’. It is the foundation of atomic theory.

(2) Galileo refutes Aristotle’s theory of motion : this leads to the foundation of the theory of acceleration, and later of Newtonian forces. Also, Galileo takes the moons of Jupiter and the phases of Venus as a refutation of Ptolemy, and thus as empirical support of the rival theory of Copernicus.

(3) Toricelli (and predecessors) : the refutation of ‘nature abhors a vacuum‘. This prepares for a mechanistic world view.

(4) Kepler’s refutation of the hypothesis of circular motion upheld till then (even by Tycho and Galileo), leads to Kepler’s laws and so to Newton’s theory.6

(5) Lavoisier’s refutation of the phlogiston theory leads to modern chemistry.

(6) The falsification of Newton’s theory of light (Young’s two- slit experiment). This leads to the Young-Fresnel theory of light. The velocity of light in moving water is another refutation. It prepares for special relativity.

(7) Oersted’s experiment is interpreted by Faraday as a refutation of the universal theory of Newtonian central forces and thus leads to the Faraday-Maxwell field theory.

(8) Atomic theory: the atomicity of the atom is refuted by the Thomson electron. This leads to the electromagnetic theory of matter, and, in time, to the rise of electronics. See Einstein’s and Weyl’s attempts at a monistic (‘unified’) theory of gravitation and electromagnetics.

(9) Michelson’s experiment (1881-1887-1902, etc.) leads to Lorentz’s Versuch einer Theorie der electrischen und optischen Erscheinungen in bewegten Körpern (1895: see §89). Lorentz’s book was crucially important to Einstein, who alluded to it twice in §9 of his relativity paper of 1905. (Einstein himself did not regard the Michelson experiment as very important.) Einstein’s special relativity theory is (a) a development of the formalism founded by Lorentz and (b) a different—that is, relativistic—interpretation of that formalism. There is no crucial experiment so far to decide between Lorentz’s and Einstein’s interpretations; but if we have to adopt action at a distance (non-locality: see Quantum Theory and the Schism in Physics, Vol. III of the Postscript, Preface 1982), then we would have to return to Lorentz.

Incidentally, it took years before physicists began to come to some agreement about the importance of Michelson’s experiments: I do not contend that falsifications are usually accepted at once (see the preceding section) not even that they are immediately recognised as potential falsifications.

(10) The ‘chance-discoveries’ of Roentgen and of Becquerel refuted certain (unconsciously held) expectations; especially Becquerel’s expectations. They had, of course, revolutionary consequences.

(11) Wilhelm Wien’s (partially) successful theory of black body radiation conflicted with the (partially) also very successful theories of SirJames Jeans and Lord Rayleigh. The refutation by Lummer and Pringsheim of the radiation formula of Rayleigh and Jeans, together with Wien’s work, leads to Planck’s quantum theory (see L.Sc.D., p. 108). In this, Planck refutes his own theory, the absolutistic interpretation of the entropy law, as opposed to a probabilistic interpretation similar to Boltzmann’s.

(12) Philipp Lenard’s experiments concerning the photoelectric effect conflicted, as Lenard himself insisted, with what was to be expected from Maxwell’s theory. They led to Einstein’s theory of light-quanta or photons (which were of course also in conflict with Maxwell), and thus, much later, to particle- wave dualism. (

(13) The refutation of the Mach-Ostwald anti-atomistic and phenomenalistic theory of matter: Einstein’s great paper on Brownian motion of 1905 suggested that Brownian motion may be interpreted as a refutation of this theory. Thus this paper did much to establish the reality of molecules and atoms. (14) Rutherford’s refutation of the vortex model of the atom.8 This leads directly to Bohr’s 1913 theory of the hydrogen atom, and thus, in the end, to quantum mechanics.

(14) Rutherford’s refutation of the vortex model of the atom.8 This leads directly to Bohr’s 1913 theory of the hydrogen atom, and thus, in the end, to quantum mechanics.

(15) Rutherford’s refutation (in 1919) of the theory that chemical elements cannot be changed artificially (though they may disintegrate spontaneously).

(16) The theory of Bohr, Kramers and Slater (see L.Sc.D., pp. 250, 243): this theory was refuted by Compton and Simon. The refutation leads almost at once to the Heisenberg-Born- Jordan quantum mechanics.

(17) Schrodinger’s interpretation of his (and de Broglie’s) theory is refuted by the statistical interpretation of matter waves (experiments of Davisson and Germer, and of George Thomson, for instance). This leads to Bom’s statistical interpretation.

(18) Anderson’s discovery of the positron (1932) refutes a lot: the theory of two elementary particles — protons and electrons — is refuted; conservation of particles is refuted; and Dirac’s own original interpretation of his predicted positive particles (he thought they were protons) is refuted. Some theoretical work of about 1930-31 is thereby corroborated.

(19) The electrical theory of matter elaborated by Einstein and Weyl, and held implicitly — and at any rate, pursued — by Einstein to the end of his life (since he interpreted the unified field theory as a theory of two fields, gravitation and electromagnetics),is refuted by the neutron and by Yukawa’s theory of nuclear forces: the Yukawa Meson. This gives rise to the theory of the nucleus.
(20) The refutation of parity conservation. (See Allan Franklin, Stud. Hist. Philos. Sci. 10, 1979, p. 201.)”
That is an interesting list of scientific refutations provided by Popper himself. Popper  was right to suggest that the new theories highlighted above were not direct results of the refutations. The refutations merely created new problem situations which stimulated imaginative and critical thought by thinking men. But this initial stage of conceiving a new theory is not susceptible for logical analysis.”The question how it happens that a new idea occurs to a man  … may be of great interest  to empirical psychology ; but it is irrelevant to the logical analysis of scientific knowledge” (See Popper, K., The  Logic of Scientific Discovery,1934,  p. 7). That is because the latter does not concern with quid facti but with quid juris.
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The Ethics of Voting

Here is Jason Brennan‘s provocative view on voting:

“In The Ethics of Voting, I argue that citizens have no standing moral obligation to vote. Voting is just one of many ways one can pay a debt to society, serve other citizens, promote the common good, exercise civic virtue, and avoid free-riding off the efforts of others. Participating in politics is nothing special, morally speaking.

However, I argue that if citizens do decide to vote, they have very strict moral obligations regarding how they vote. I argue that citizens must vote for what they justifiedly believe will promote the common good, or otherwise they must abstain.

That is, voters should vote on the basis of sound evidence. They must put in heavy work to make sure their reasons for voting as they do are morally and epistemically justified. In general, they must vote for the common good rather than for narrow self-interest. Citizens who are unwilling or unable to put in the hard work of becoming good voters should not vote at all. They should stay home on election day rather than pollute the polls with their bad votes.

and that is his interesting interview with Robert Talisse on the New books in philosophy blog:

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The Simulation Argument

Nick Bostrom doesn’t rule out the possibility that he might be part of a computer simulation in this interview with Nigel Warburton.


Find out more in the podcast below



The Rorty Discussion with Donald Davidson

An interesting discussion between two great philosophers of the latter half of the 20th century, exploring topics such as truth, meaning and reference.


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The Duty of Inquiry: William K. Clifford (II)

See below another nice passage from the classic “Ethics of Belief” of William K. Clifford:

A shipowner was about to send to sea an emigrant-ship. He knew that she was old, and not well built at the first; that she had seen many seas and climes, and often had needed repairs. Doubts had been suggested to him that possibly she was not seaworthy. These doubts preyed upon his mind, and made him unhappy; he thought that perhaps he ought to have her thoroughly overhauled and refitted, even though this should put him at great expense. Before the ship sailed, however, he succeeded in overcoming these melancholy reflections. He said to himself that she had gone safely through so many voyages and weathered so many storms that it was idle to suppose she would not come safely home from this trip also. He would put his trust in Providence, which could hardly fail to protect all these unhappy families that were leaving their fatherland to seek for better times elsewhere. He would dismiss from his mind all ungenerous suspicions about the honesty of builders and contractors. In such ways he acquired a sincere and comfortable conviction that his vessel was thoroughly safe and seaworthy; he watched her departure with a light heart, and benevolent wishes for the success of the exiles in their strange new home that was to be; and he got his insurance-money when she went down in mid-ocean and told no tales.


So the shipowner has formed a sincere “faith” in his ship. However we would all surely find this faith discreditable. Sincerity does not alone fulfill the duties implied by the process of rational belief formation. Or as Clifford comments:


the sincerity of his conviction can in no wise help him, because he had no right to believe on such evidence as was before him. He had acquired his belief not by honestly earning it in patient investigation, but by stifling his doubts. And although in the end he may have felt so sure about it that he could not think otherwise, yet inasmuch as he had knowingly and willingly worked himself into that frame of mind, he must be held responsible for it.

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The Ethics of Belief: William K. Clifford

Here is a beautiful excerpt from the “Ethics of Belief” of William K. Clifford which I thought I should share with you:

If a man, holding a belief which he was taught in childhood or persuaded of afterwards, keeps down and pushes away any doubts which arise about it in his mind, purposely avoids the reading of books and the company of men that call into question or discuss it, and regards as impious those questions which cannot easily be asked without disturbing it — the life of that man is one long sin against mankind….

“But,” says one, “I am a busy man; I have no time for the long course of study which would be necessary to make me in any degree a competent judge of certain questions, or even able to understand the nature of the arguments.”

Then he should have no time to believe.


He who truly believes that which prompts him to an action has looked upon the action to lust after it, he has committed it already in his heart. If a belief is not realized immediately in open deeds, it is stored up for the guidance of the future. It goes to make a part of that aggregate of beliefs which is the link between sensation and action at every moment of all our lives, and which is so organized and compacted together that no part of it can be isolated from the rest, but every new addition modifies the structure of the whole. No real belief, however trifling and fragmentary it may seem, is ever truly insignificant; it prepares us to receive more of its like, confirms those which resembled it before, and weakens others; and so gradually it lays a stealthy train in our inmost thoughts, which may someday explode into overt action, and leave its stamp upon our character for ever.


Intentions Revisited

Further to my previous blog post about intentions I thought I should present a similar version of the same problem (the Knobe‘s CEO example)

[Harm] A CEO for a large corporation is presented with a new money-making scheme and he is told that the scheme will harm the environment. The CEO says, “I don’t care about the environment, I just want to make money.” The scheme is implemented, and the environment is harmed. Did the CEO harm the environment intentionally?

[Help] A CEO for a large corporation is presented with a new money-making scheme and he is told that the scheme will help the environment. The CEO says, “I don’t care about the environment, I just want to make money.” The scheme is implemented, and the environment is helped. Did the CEO help the environment intentionally?

So how do you see this case and why?

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