Saturday 3 November 2018

Sustainable Energy - without the hot air: 10 years on

The free to download ebook version of Sustainable Energy — without the hot air was last issued on the 3rd of November 2008. Ten years have passed since this important and influential science based look at sustainable energy was updated. I am sure that if it was not for the early death of David MacKay, he would have built upon this achievement and updated and evolved his position. There have been calls for a collective effort to keep this book up to date, notably from Chris Goodall. This has not gained very much traction but books do tend to need a high level of personal ownership to advance.

Let's look at the approach MacKay took as it has been particularly robust to intervening events. Rather than focus on what 2008 technology could do he used physics to bound what is in principle achievable. He attempted to answer the following question as honestly as possible: how much energy is there to be harvested practically and in a sustainable form? Questions of social, economic and wider environmental impacts were not ignored. These factors lead to MacKay to propose a number of plans, of which the feasibility and affordability will depend on technical and behavioural developments. They each add up to 70 kWh per person per day (estimated consumption in 2008 was 125 kWh per person per day) and are shown below.

David MacKay provided a ten page summary and the details of the figure above are explained there. The presence of Nuclear and "Clean Coal" will not please environmental purists but MacKay's approach is pragmatic and clear that dealing with climate change will require major sacrifices, of which green sensitivities are not the most onerous. For any of these plans to be feasible MacKay's analysis points to a 25% improvement in heating efficiency and a 50% improvement for transport and other efficiency savings that must reduce overall energy consumption to about 60% of 2008 levels.. His analysis does not show that it will be easy to achieve this nor that it is achievable then or now through established technology.  He does argue persuasively that there no barriers in physics. This analysis lays bare, although largely implicit in the book, the need for political leadership and imagination that will galvanise humanity to meet the challenge.

Let's pause to reflect what an achievement the book was, how well it stands up against developments and what a loss David MacKay's early death was. Since 2008 the acceptance of the evidence for climate change and its human generated causes has gained much wider informed acceptance. The case for a technically grounded response to the challenge has never been stronger and MacKays example needs to be followed and acted upon. Science does not only provide the analysis but also the foundation for the technology that the solution to the climate change challenge will require.

Tuesday 18 September 2018

Reclaiming and renewing liberalism: Free Trade

Free Trade as manifested in the repeal of the Corn Laws was a founding event for the Liberal Party. There are signs however that liberals are becoming wary of the phrase. This a clear symptom of the malady that the The Orange Book was seeking to address fourteen years ago. The ailment is that key liberal ideas have been appropriated and distorted by the Conservative Party and in the case of the phrase "Free Trade" by the right wing of that party. So, by association in the minds of many with a weak grasp of history the phrase has become in the UK a right wing Conservative slogan and tainted for that reason.

The phrase "Free Trade" on its own is open to a number of interpretations and requires context to clarify which interpretation is meant. On the Conservative right the freedom being emphasised is freedom from regulation. Liberals have long since moved on from a 19th century laissez-faire philosophy. Freedom should be understood as the liberty of all parties to enter into an exchange or not. This means commerce and trade is in harmony with the core liberal value of individual liberty. Domestically, it has long been recognised that the rule of law is required for competitive markets to flourish. Internationally a system of rules is required to allow trade between and across nations to be effective. Agreements that include harmonisation of regulations are necessary but we should be limiting them where possible to concerns like safety in the food chain or of electrical products, for example. Regulations should not be used to skew advantage to one party or a particular group.

Liberalism is a dynamic and adaptable philosophy. Today's goods and services are of a complexity that makes a laissez-faire approach, suitable for corn, unfit for the exchange of contemporary goods and services.  It is this dynamic and forward looking liberalism that is presented in A manifesto for renewing liberalism. But here too there a sign that the phrase "Free Trade" is not to be used and "Open Markets" used as a replacement. Are we to give in to the loud and strident Conservative right and cease talking directly about Free Trade and its benefits?

No, while looking forward, it is important to mark and take pride in key historical achievements. To the fore among these is the establishment of Free Trade as the engine of growth in the 19th century and then its resurgence after the 2nd World War based on a system of agreements and rules that recognise and protect human freedoms and rights.  So let us not be bullied out of using the phrase and support Free Trade as the strongest economic mechanism yet discovered for fostering growth and relieving poverty.

Tuesday 7 August 2018

Values: liberty and its supporting mechanisms

Liberalism is often characterised as a compromise philosophy, with individual freedom being in essential conflict with egalitarian views on justice. The values that are thought of as liberal are often represented as forming some watered down consensus where everything is a compromise for a comfortable life. These values are gathered into lists such as that provided for school projects on "British Values".  According to Ofsted, British Values are:
  • Democracy
  • The rule of law
  • Individual liberty
  • Mutual respect for and tolerance of those with different faiths and beliefs and for those without faith.
This list seems fine on first reading and serves well as a starting point. Here, I will use it as such. 

Here I will defend the view that liberalism can form a coherent philosophy with a system values distinct from socialism (democratic or not) and conservatism.

Personal liberty, a fundamental liberal value and effectively tautologous and so does not need an argument to be included.  It is on the Ofsted list as equivalent to their third bullet, but what is the status of the others on the list. I acknowledge that all are important, with a reservation on the fourth,  and mostly to be cherished but are they equally fundamental or even values? Of the possible meanings of "values" consider (Oxford):
  1. One's judgement of what is important in life; 
  2. Principles or standards of behaviour.
Each item on the Ofsted list can be interpreted consistently with the first meaning. Only the fourth on the list is clearly consistent with the second meaning but the others could be coaxed into an acceptable format. Equality is omitted from the Ofsted list as is freedom from violence.

Is it possible to do better with our values than provide a bland list? Can some structure be provided or a theory that explains away the perceived conflicts to provide an coherent mesh of values?

Here the value adopted to start the critical discussion is personal liberty for all where each individual is limited only to do no harm to others. By personal liberty I mean (provisionally) freedom of choice and action. All, so far, quite uncontroversial and consistent with Mill's position in the classic On Liberty. The question to be addressed here is: what are the other candidates for liberal values and whether any are as fundamental to liberalism as personal freedom? The obvious ones that spring to mind are democracy, equality, freedom from violence, rule of law and economic freedom. Economic freedom is included because some claim it as a fundamental freedom. In addition, under the name Capitalism, economic liberalism is often described as an ideology by its opponents, often communists but significantly milder socialists and radicals too.

Of the three additional candidates outlined above the one that I think would get the most support, as a value, is democracy. Indeed there are democrats on the extremes (but not always too extreme) of the political left and right who may even value democracy over personal liberty. So is democracy a candidate liberal value or is it something else such as a supporting concept or an enabling mechanism?

It is a tenet of classical liberalism that democracy, just as any form of government, must be held in check by constitutional measures to avoid effects such as the tyranny of the majority. This in itself is not too different from the constraints on personal liberty but here the reason to constrain democracy is to protect personal liberty. Therefore making liberty prior or a more fundamental value. So, why democracy? The strongest reason for a democratic political constitution is to enable the non-violent removal of bad governments (as argued convincingly by Karl Popper). It is desirable for democratic governments to make good positive decisions but scepticism about there capacity to deliver effectively a wide range of services as opposed to laws and regulations is justified by much evidence. Not adopting democracy as a fundamental value is not to de- or under- value it. Supporting mechanisms are essential for values to make  their effect.

This means that freedom from violence is also more fundamental than democracy. A constitutional democracy must have mechanisms to return at regular intervals to the opportunity to change government. On democracy as a decision making mechanism there is sufficient analysis on voting systems to show that there is no generally applicable voting rule to obtain optimal decisions. Therefore democracy cannot be defended a generally effective decision making mechanism. So what  the people vote for needs to be constrained based on the more fundamental freedoms of personal liberty and freedom from violence. Although not optimal, voting does provide a way to arrive at pragmatic acceptable outcomes in many cases. This pragmatism justification means there are a number of candidate constitutional arrangement that have evolved or been chosen to implement a democratic order. 

All this makes democracy an essential enabling mechanism to ensure a satisficing degree of personal liberty and a considerable measure of security from violent acts. It could be argued that freedom from violence is part of personal liberty but they are to considerable extent independent. In a social situation less enlightened than the one we enjoy in western Europe, and some places elsewhere, we can well imagine a preference for freedom from violence over personal freedom and even sacrificing freedom to gain security. Democracy, correctly implemented, provides some guarantees against violence by government against its own population but for more general protection we need to look to the Rule of Law. The Rule of Law is, like democracy, not a liberal value in itself but a mechanism that constrains the freedom of persons or groups but leaves a valued measure of personal liberty to be enjoyed in safety and security.

Economic freedom is often taken a tradition liberal value.  There is ample historical evidence that, given the opportunity, reasonably free persons will organise spontaneously into cooperative groups that eventually give rise to market structures at their local level. In time groups will interact to produce a wider market order.  Analysis of market mechanisms show that they enable cooperation and creation of wealth without coercion. The wealth creation of the market provides the resources to make practicable the desires and actions of free persons. Thus economic freedom is an enabler or mechanism and that is also the case if emerging economic order is labelled Capitalism. It is an enabling mechanism, not a value let alone an ideology, and as such required regulation and a legal framework. Within this  context of values and mechanisms, individual freedom transform in a concept of individual liberty that is enhanced through equality of opportunity, rule of law and open markets.

So, to summarise personal liberty along with freedom from violence are distinct if still mutually influencing values. Democracy, Economic Freedom and the Role of Law are enabling mechanisms. So one fundamental value has been added that is not on Ofsted's list. Democracy and the Rule of Law become essential enabling mechanism along this economic freedom as instantiated in the competitive market order. That leaves the last Ofsted value. It looks like an awkward add on and I would argue that it essentially a polite statement of a desirable attitude that is fundamentally derived from the moral equality of individuals. However one aspect of it is fundamental and that is tolerance. Tolerance is what enables the other aspects of liberalism to work together as a system.

I end by proposing an alternative ranked set of fundamental values to be guaranteed by a constitutional liberal democratic order:
  1. Freedom from violence
  2. Personal Liberty
  3. Equality of opportunity.
  4. Tolerance of other individuals or groups that are not causing harm
These being supported by the mechanisms of democracy, rule of law and markets.

Friday 13 July 2018

Liberal leadership in ideas: the welfare state

I have never liked the term "welfare state" with is paternalist tone, preferring "social state" derived from the German Sozialstaat  and fitting with the concept of the social market as a regulated, fair and free economy. It was interesting to read today in The Economist (Repairing the safety net - The welfare state needs updating) that the founding spirit of the UK welfare state, the Liberal William Beveridge, didn't like the term either. However, and more importantly, in that article  and the introductory leader -   - the point is made that it was the liberal philosophy of Beveridge that informed the identification of the need, scope and form of the UK welfare reforms of the  late 1940's. The main thrust of these articles in The Economist is that we must return to liberal values and creative thought on the mutually supporting nature of effective welfare with effective wealth creation to redesign the welfare state.

As chance would have it, this is a topic I addressed in a recent post, Hayek and the welfare state, in which the argument was made that a principled and human approach to welfare was not only compatible with but should be an essential complement to the market economy. This is  very much the tone of the pieces in The Economist too.

Years of tinkering and short term politically motivated meddling from left and right have led to the UK social protections becoming a bureaucratic entanglement that is costly and provide at best a second rate service. In addition the weakening of the liberal tradition, Liberal Party and the consequent decrease in influence have contributed to this state of affairs.This is not the time to roll back to 1945 in terms of detail and implementation but just as the market has evolved to become more diverse and international, social protection must also be thought through again. Neither is it a mere matter of picking up The Orange Book, but it does provide a valuable starting point. What should be returned to is the core liberal philosophy with its humane side personified by Beveridge dealing with the “Five Giants”: disease, idleness, ignorance, squalor and want, and it competitive market foundation for the creation of wealth. We can look to the rounded enlightened figures such as Adam Smith and John Stuart Mill as well as the more austere Friedrich Hayek. Nor should the still very pertinent thinking of the German social market economists such as Walter Eucken be neglected, as well as others across the world. One of most recent champions of liberal enlightenment values, Steven Pinker in Enlightenment  Now, was a pains to stress that it is the combination of social care and wealth creation that has given us the progress in global well-being that he documents in such detail.

Reform is needed to deal with affordability and fairness of a social provision system that is designed to provide the safeguards that foster wealth creation rather than undermine it. The social safety measures must provide quality services that people are proud to use and are proud of the society that provides them. Services such as the NHS do not provide this quality and are currently condemned not to be  capable of delivering it, as outlined in a recent opinion piece by Matthew Parris.

To repeat the essential points from my earlier post; four principles can be proposed to help design social insurance that can enhance market dynamism and economic freedom in a Free-Market Welfare State:
  • Risk and Entrepreneurship.  As the term “safety net” suggests, social insurance can enhance risk-taking and entrepreneurship by ensuring failure is not catastrophic.
  • Search and Adjustment Costs. Workers who are laid off in periods of market restructuring should be ensured a smooth transition through appropriate wage replacements and active labour-market policies. While your job may not be secure, your employment is. 
  • Benefit Portability. Markets work best when social benefits follow the individual and are detached from any particular firm or market structure. (In the UK many people are often trapped in a firm due to penalties imposed to their pension entitlement. In contrast the German system decouples this, as recommended.)
  • Migration Robustness. Welfare benefits should be payments or services resulting from insurance funds to which people have contributed while working in the host country, migrants who claim such benefits should not therefore be perceived to be a great problem. There needs to be further humanitarian safeguards for refugees and others in dire need; as opposed to economic migrants.

Conditional probability: Renyi axioms

In earlier posts the relationship of the material conditional to conditional probability and the role of Leibniz in the early philosophy of probability where discussed. In both posts the case for taking conditional probability as fundamental was made or implied. How far this will resolve the difficulties in combining aspects of propositional logic with probability theory remains to be seen but it is worth taking time to explain a full axiomisation with conditional probability as fundamental. A further consideration is the clarification of distinct role of conditional probability in the epistemic and the objective (ontological) interpretations.

In his Foundations of Probability  Renyi provided an alternative axiomisation to that of Kolmogorov that takes conditional probability as the fundamental notion, otherwise he stays as close as possible to Kolmogorov. Renyi has provided a direct axiomatisation of quantitative conditional probability. In brief, Renyi's conditional probability space $(\Omega, \mathcal{F} (, \mathcal{G}, P(F | G))$ is defined as follows. The set $\Omega$ is the sample space of elementary events and $\mathcal{F}$ is a $\sigma$-field of subsets of $\Omega$ (so far as with Kolmogorov) and $\mathcal{G}$, a subset of $\mathcal{F}$ (called the set of admissible conditions) having the properties:
(a) $ G_1, G_2 \in \mathcal{G} \Rightarrow G_1 \cup G_2 \in \mathcal{G}$,
(b) $\exists \{G_n\}, \cup_{n=1}^{\infty} G_n = \Omega,$
(c) $\emptyset \notin \mathcal{G}$,
$P$ is the conditional probability function satisfying the following four axioms.
R0. $ P : \mathcal{F} \times \mathcal{G} \rightarrow [0, 1]$,
R1. $ (\forall G \in \mathcal{G} ) ,  P(G | G) = 1.$
R2. $(\forall G \in \mathcal{G}) , P(\centerdot | G)$ , is a countably additive measure on $\mathcal{F}$.
R3. $(\forall G_1, G_2 \in \mathcal{G}) G_2 \subseteq G_1 \Rightarrow P(G_2 | G_1) > 0$, $$(\forall F \in \mathcal{F}) P(F|G_2 ) = { \frac{P(F \cap G_2 | G_1)}{P(G_2 | G_1)}}.$$
What has this won over the more well known Kolmogorov formulation?

A number of examples have been highlighted by Stephen Mumford, Rani Lill Anjum and Johan Arnt Myrstad in What Tends to Be, Chapter 6. These have been analysed by them using absolute probabilities as fundamental, so a Kolmogorov type framework, and these examples will be revisited here using Renyi's formulation. The critique of Mumford et all is based on a development of the development of an ontological point of view that has the potential to clarify physical propensities as a degree of causal disposition. The explicit clarification of the example within Renyi's axiomisation shows that by adopting it the path is open to mathematically modelling physical propensities as causal dispositions.

Here is the first example that is thought to indicate a problem with absolute probability (absolute probability will be denoted by $\mu$ below to avoid confusion with Renyi's function $P$).
P1. Let $\mu(A) = 1$ then $\mu(A | B) =1$, $\mu$ is Kolmogorov's absolute probability
We can calculate this result from Kolmogorov's conditional probability postulate as follows: since $\mu(A \cap B) = \mu(B)$, $\mu(A|B) = \mu(A \cap B)/\mu(B) = \mu(B)/\mu(B)=1$. Why is this problematic? Not at all if you stay inside the formal mathematics but is if $\mu(A|B)$ is to be understood as a degree of implication. Is it not reasonable that there must exist a a condition under which the probability of $A$ decreases? A consequence of Renyi's theory is that these Kolmogorov absolute probabilities can be obtained by conditioning on the entire sample space
$$ \mu(A) \equiv P(A|\Omega).$$
Then $\mu(A)=1$ means $P(A|\Omega)=1$ and again (by R3.)
$$P(A|B) = { \frac{P(F \cap B | \Omega)}{P(B |\Omega)}}=1 $$
independently of choice of $B$ which must be a subset of $\Omega$. Thus, giving the same result. However if we are not working within a global conditioning on the entire $\Omega$ but on a proper subset of $\Omega$ called $G$, say, then $\mu(A)=1$ has no consequence for $P(A|G)$ and in a addition it is now possible to pick another conditioning subset of $\Omega$, $G'$, such that $G' \not\subseteq G$ then R3. does not apply and therefore the value of  $P(A|G)$ and $P(A|G')$ have to be evaluated separately. That is, it is a modelling choice. How they are evaluated depends on whether an epistemic or an objective interpretation of $P$ is being used.

A further problematic consequence of Kolmogorov's conditional probability is when $A$ and $B$ are probabilistically independent
P2. $\mu (A\cap B)=\mu(A )\mu(B)$ implies $\mu(A|B)=\mu(A)$⋅
In general Renyi's formulation does not allow this analysis to be carried out. This is because the Kolmogorov conditional probability formula only holds under special conditions, see  R3.  Independence, in Renyi's scheme, is only defined with reference to some conditioning set, $C$ say. In which case probabilistic independence is defined by the condition
$$ P(A \cap B |C) = P(A|C)P(B|C)$$
and as a consequence it is only if  $B \subseteq C$ that
$$   P(A|B ) = { \frac{P(A \cap B | C)}{P(B | C)}} = P(A|C)$$
that is, only if $C$ includes $B$. Therefore, $P(A|C)$ being large only implies $P(A|B)$ is equally large when $C$ inudes $B$, using the mapping to the material implication in propositional logic as shown in  the earlier post.

The third example, P3.,  is that regardless of the probabilistic relation between $A$ and $B$, a third consequence of the Kolmogorov conditional probability definition is that whenever the probability of $A$ and $B$ is high $\mu(A|B)$ is high and so is $\mu(B|A)$:
P3. $(\mu(A \cap B) \sim 1) \Rightarrow((\mu(A|B) \sim 1) \land \mu(B|A) \sim 1))$
As above this carries over into Renyi's axiomisation only for the case of conditionalisation on the whole sample space. If another conditioning set is used, call it $C$ again, then P3. does not hold in general. It does hold, or its equivalent does, when both $A$ and $B$ are subsets of $C$ but that is then a reasonable conclusion for the special case of both $A$ and $B$ included in $C$.

Tuesday 10 July 2018

Leibniz and the propensity interpretation of probability

The point of focus here are the propensity interpretation of probability theory, in which probabilities are physical tendencies that cause events. Contemporary interest in the interpretation is down to Karl Popper and been picked up by Mellor. It is now playing a role in the dispositional metaphysics of objective chance. The origins and initial philosophical discussion of probability can be traced to Pascal and Leibniz and, it is argued, something close to the propensity interpretation attributable to Leibniz too. This role of Leibniz came as surprise on reading The Emergence of Probability by Ian Hacking. Hacking presents Leibniz as the first philosopher of probability and principal guide to the early development of the theory. In addition, as is often the case, the thinking of Leibniz was ahead of his own epoch and many of his points can best be appreciate only following developments in the 20th century.

The origin of probability as a useful science is primarily attributed to Blaise Pascal (1623-1662) and Pierre de Fermat (1601-1665) in a correspondence motivated by a request from Chevalier de Méré for mathematical guidance on games of chance. The answer that Pascal and Fermat developed is that Probability Theory is built upon a fundamental set of equally likely outcomes. This approach is somewhat circular but can be interpreted as an argument based on symmetry and this leads Leibniz naturally to the to the argument from indifference in the interpretation of the theory of probability.

The principle of indifference can take various forms:
  • If there is no reason that one event or outcome will happen more often than an other then they are equiprobable
  • If there is no reason to prefer the outcome of one event over another then they are equiprobable
  • If it is believed that one event will be no more likely to happen than another then they are equiprobable.
The interpretations of probability that derive from Pascal’s principle of symmetry (or equally likely cases) must be distinguished from the logical interpretation. Like so much of his work, most of Leibniz's thoughts on the relationship between probability and logic were not published in his lifetime, however there are important letters. Here as a representative and published quotation from Nouveaux Essais sur l’entendement humain
J’ay dit plus d’une fois qu’il faudroit une nouvelle espece de Logique, qui traiteroit des degrés de probabilité, . . .(I have said more than once that there is need of new type of logic, which will deal with the degrees of probability ...)
Leibniz was more optimistic that this can be done than Locke, who viewed it as “impossible to reduce to precise rules the various degrees wherein men give their assent.” Leibniz believed that a logical analysis of conditional implication would yield such rules, however, this is still considered problematic. The relationship that he saw here was that probability is useful when there is insufficient knowledge to make a rigorous deduction. Leibniz and his logical approach began from legal considerations (he trained as a lawyer), where there is uncertainty in the determination of a question of right (e.g., to property) or guilt. His approach is also important for the emphasis that conditional or relational probabilities are fundamental.

As a young man of 19, Leibniz published a paper proposing a numerical measure of proof for legal cases: “degrees of probability.” His goal was to render jurisprudence into an axiomatic deductive system akin to Euclidean geometry. So, the goal was to transform evidence (a legal notion), into something to be measured by some allocation of weight that will make calculation of justice possible. However, he was also convinced that there had to be an objective and correct situation. From this he developed a dual interpretation of probability:
  • Epistemic - dealing with uncertainty due to lack of knowledge
  • Objective - dealing with the degree feasibility for possibilities to be physically realised.
The epistemic view came first, initially dominated and its conditional character was inherited through its emergence from legal considerations. A bridge is provided from the legal term cases or casu in latin which also means events. Events happen and are part of the standard terminology in modern probability theory. Another term, important across Leibniz's philosophy, is possibility. Leibniz associated equi-possibility with probability and asserted that probability is a degree of possibility. Here he means by possibility the power to achieve various events. In a letter to Bourguet (in Die Philosophischen Schriften von Gottfried Wilhelm Leibniz: Band 3 ed Gerhardt) Leibniz states:
L'art de conjecturer est fondée sûr ce qui est plus ou moins facile, ou bien plus ou moins faisable ... (The art of conjecture is founded on that which is more or less easy or, better, more or less feasible ...)
So, there are now degrees of feasibility that are not dependent on any state of knowledge. However, these degrees of feasibility, propensities, objective possibilities can be themselves objects of knowledge.

Leibniz distinguishes epistemic probability that some possibility is realised and the physical, objective or ontological propensity for some possibility to exist. The relationship between the two is still problematic. For Leibniz, every possibility tends to exist and so every possible world has its tendency to exist to a degree that depends on its feasibility. Leibniz had access to a metaphysical synthesis that provides important insights even if we cannot subscribe to it.

Monday 9 July 2018

Material implication and conditional probability

A simple argument shows that in general the ratio formula for conditional probability cannot be the probability of the material conditional. But there is still controversy over both.

Despite the undoubted success of probability theory in providing tools for inference, statistical analysis and decision making, there remain concerns about its foundations. A major concern is with the status of conditional probability and its relationship with logical implication (indicative conditional). In propositional logic material implication provide the formal concept. Although this is often glossed over in standard texts it is taken seriously by E. W. Adams. However his solution giving primacy to conditional probability is also open to criticism.  These points are of practical importance as status of inference and its foundations in logic, probability and set theory are fundamental to the development of Artificial Intelligence

Adams’ thesis is that the assertability of the indicative conditional $A \to B$ is given by the conditional probability of $B$, given $A$. For example, he writes: “Take a conditional which is highly assertible, say, ‘If unemployment drops sharply, the unions will be pleased’; it will invariably be one whose consequent is highly probable given the antecedent. And, indeed, the probability that the unions will be pleased given unemployment drops sharply is very high”

The default standard foundation of probability theory is the axiomisation of A.N. Kolmogorov. This takes as one of its primitives a function denoting the probability of a set and these sets are called random events. An event is something that happens or has the potential to happen.

In Kolmogorov's theory probability space $\left( \Omega, \Sigma,\mu \right)$ consists of a set $\Omega$ (called the sample space), a $\sigma$-algebra $\Sigma$ of subsets of $\Omega$ (i.e., a set of subsets of $\Omega$ containing $\Omega$ and closed under complementation and countable union, but not necessarily consisting of all subsets of $\Omega$) whose elements are called measurable sets, and a probability measure $\mu:\Sigma \rightarrow \lbrack 0,1\rbrack$ satisfying the following properties:
P1. ${\mu}\left(X \right){\geq 0}$ for all $X \in \Sigma$
P2. ${\mu}\left( \Omega \right){= 1}$
P3. ${\mu}\left( {\bigcup}_{i = 1}^{\infty}{\ }X_{i} \right){= \ }\sum_{i = 1}^{\infty}{\mu(}X_{i}{)}$, if the $X_{i}$'s are pairwise disjoint members of $\Sigma$.
P4. $\mu(A | B) = \frac{\mu(A \cap B) }{\mu(B)}$
Postulate P4 provides an analysis of conditional probability. It is more often referred to as the definition. However conditional probability was current as a concept prior to the axiomisation. In the sense of
The probability of $A$ given $B$,
The probability of "if $B$ then $A$"
The probability that $B$ implies $A$.
 In the usage prior to the formalisation of probability $A$ and $B$ are not sets but usually statements or propositions. So a relationship between propositions and sets is needed.

In propositional logic, material implication is a rule of replacement that allows for a conditional statement to be replaced by a disjunction in which the antecedent is negated. The rule states that $P$ implies $Q$ is logically equivalent to not-$P$ (in symbols $\neg P$) or $Q$.
$$ P \to Q \Leftrightarrow \neg P\lor Q$$
where $\Leftrightarrow$ denotes logical equivalence.

There is a straight forward mapping between the sets and connectives in the set based axiomisation and the the propositions and connectives in propositional logic. The correspondence of connectives is:
  • $\cup$ corresponds to $\lor $
  • $\cap$ corresponds to $\land$
  • $\Omega$ corresponds to $\mathbf{t}$ (the single extension of all tautologies)
  • $\emptyset$ corresponds to $\mathbf{f}$ (the single extension of all falsehoods)
  • The set complement ($\bar{A}$ for any $A \in \Sigma$) corresponds to $\neg$ (negation). 
This would mean
  • $\bar{A} \cup B$ corresponds to $P \to Q$, where proposition $P$ pertains to the event represented by $A$ and $Q$ pertains to the event represented by $B$.
So, what is the relationship between $\mu(A | B)$ and $\mu(\bar{A} \cup B)$? A simple analysis shows that they are only equal in a very special case. Consider the partition of $\Omega$ shown in the diagram below.

 From this it follows:
$$ \mu(B|A) = \frac{c}{a+c}$$
$$ \mu(\bar{A} \cup B) = b+c+d = 1-a$$
Therefore, in this case,
$$ \mu(B|A) = P(\bar{A} \cup B) \Rightarrow P(A)=1$$.

So the two terms are only equal when $A$ is the certain event. In general, the ratio formula for conditional probability cannot be the probability of the material conditional. In general, the relationship is
$$\mu(\bar{A} \cup B) = 1 - \mu(A)(1- \mu(B|A))$$
This is equivalent to the result stated by E. W. Adams in "The Logic of Conditionals: An Application of Probability to Deductive Logic" page 3.

The morphism between propositional logic and set theory is used extensively in interpreting theories of probability. It preserves structure but does not extend to implication and it does not entail that meaning or ontological status is preserved. It is from the direction of metaphysical analysis of the ontological status of conditionals, both logical and probabilistic, that progress may be made. In a recently published book,  What Tends to Be, Rani Lill Anjum and Stephen Mumford provide a synthesis of this analysis.

In probability theory alternative axiom systems may be the answer and candidates exist from Renyi and Popper. However, the ontological analysis may indicate that the eventual practical answers lie in something more akin to physics rather than logic or mathematics. Future posts will engage critically with this work.

Tuesday 3 July 2018

Beyond the Evidence Base - the strength of causal explanations

The term "evidence based" is often used in statements in health care or science policy that are intended to indicate respect for a scientific approach. Indeed evidence is essential for testing scientific theories and specific statements but science provides something much more powerful and that is an explanatory theory.

Theories arise in science through a critical process that incorporates much debate and draws on past theories, philosophy (if only implicitly) and, of course, evidence. Having passed several tests and often having gone through several formulations a theory will be accepted quite generally as the best current explanation of the facts in the domain to which it applies. The main point to be made here is that the power of the theory goes beyond, and cannot be derived from, the evidence. This provides the ability to understand and predict states of affairs that are not covered by the current evidence base.

The power of explanatory theory can be used to eliminate, provisionally, courses of action and to guide positive proposals. As an example of how a philosophical analysis can contribute to clarifying these issues there is  a recent paper by Rani Lil Anjum "Evidence Based or Person Centered? An Ontological Debate" that uses the example of health care to analyse the limitations of the "evidence based" approach. This critiques the positivist underpinning of Evidence Based Medicine and provides a strong alternative. Lip service is still paid by some prominent scientists but following the work of Karl Popper and others its limitations are clear. However the work of Anjum with her colleague Stephen Mumford is developing philosophical tools that provide a conceptual framework for developing comprehensive causal explanations founded on a dispositional ontology.

Because scientific theories provide explanations that go beyond  the evidence base, they can make strong statements about situations where the evidence is missing and can be too difficult or expensive to generate. However, there is a risk that Evidence Base arguments will be used to undermine the power that theory provides to spell out the consequences of misguided actions. Climate change provides a simple example of an area where well established theory can make statements of global significance. The well established consequences of adding CO2 to the atmosphere together with the input that mankind has indeed added vast quantities of CO2 provides very strong and simple case for human driven climate change. That is, that human action is a cause of climate change. In greater detail the same theories can quantify and provide testable predictions, and an increased evidence base is the output rather than the input.

Friday 29 June 2018

Hayek and the welfare state

In the minds of many, the rigorous classical liberalism personified by Friedrich von Hayek is in direct opposition to the notion of the welfare state. But is this necessarily true? Three fundamental pillars to Hayek's thought are:
  1. The price mechanism in the market economy is a decentralised information signalling system.
  2. The competitive market is a spontaneous order (not centrally planned)
  3.  The competitive market is the economic order that supports personal liberty.
Are these compatible with a welfare state? Contrary to what is often claimed, it can be argued that the state's welfare provision may not only be compatible with fair and competitive markets but can enhance their effectiveness.
In “The Free-Market Welfare State: Preserving dynamism in a volatile world.”  by Samuel Hammond, of the Niskanen Center, an attempt is made to bridge the divide between social and economic liberals. Hammond's paper provides a fundamental change to the conventional economic view on welfare as a cost to it being implemented as an economic benefit. The arguments in the paper are set out in an US context but draw on key mechanism from northern European market economies. Notably not the UK, which would be analysed as getting the relationship mostly wrong, but with the Swedish and Danish. In terms of income levels provided by cash minimum-income benefits (Figure 1 in the paper), the UK is one of the more generous nations whereas "the U.S. income security system one of the stingiest in the developed world". So the situation in the later is fundamentally different from the former. In the US nervousness about market disruption has led to very low levels of cash benefits and the  system is poorly implemented, whereas in the UK the problem is mainly poor implementation. The UK implementation deficient in at least two ways:
  1. Welfare is poorly implemented as safety net and worse as a service (and made worse through recent reforms, as well as under funding).
  2. Welfare, as implemented, is a negative for the economy as measured against all three of Hayek's pillars, above. 
Using the statistical evidence that shows Sweden and Denmark scoring highly on personal and economic liberty and examining the welfare mechanisms they use, Hammond proposes four design principles where well implemented social insurance can enhance market dynamism and economic freedom in Free-Market Welfare State. These can be condensed (with some simplification) as follows:
  1. Risk and Entrepreneurship.  As the term “safety net” suggests, social insurance can enhance risk-taking and entrepreneurship by ensuring failure is not catastrophic.
  2. Search and Adjustment Costs. Workers who are laid off in periods of market restructuring should be ensured a smooth transition through appropriate wage replacements and active labour-market policies. While your job may not be secure, your employment is. 
  3. Benefit Portability. Markets work best when social benefits follow the individual and are detached from any particular firm or market structure. (In the UK many people are often trapped in a firm due to penalties imposed to their pension entitlement. In contrast the German system decouples this, as recommended.)
  4. Migration Robustness. Welfare benefits should be payments or services resulting from insurance funds to which people have contributed while working in the host country, migrants who claim such benefits should not therefore be perceived to be a great problem. There needs to be other humanitarian safeguards for refugees and others in dire need;as opposed to economic migrants.
Hammond's paper shows a refreshing ambition to bridge the divide between economic liberal purism (bordering on the libertarian) and social liberalism with its focus on social safety nets.

The above is obviously at best work in progress from the point of view of policy formulation and implementation. The proposal is that, by adopting the four principles for welfare design, Hayek's three pillars of liberty can be maintained and their effectiveness even enhanced.

A constitution for a confederate Europe - beyond the nation state

The traditional nation state is not enough to ensure prosperity, security and freedom in a world of multi-national  interests. The solution is not to grow larger nation states but to move beyond them to associations or confederations where there is a consensus on core values.

Getting this right poses considerable constitutional challenges. The European Union has developed into an unintentional experiment in this process. There is, however lack of clarity on the principles and values guiding the process. The Prometheus Institut  has proposed a Manifest for a confederate Europe.  In this document it argues for  a confederation of constitutionally liberal states.

The core principles of a future EU constitution should be the common market for goods and services and free trade with the rest of the world. The confederate Europe will require a liberal monetary policy that does not divide Europe into different classes within a rigid framework of a common currency. Additionally, states that will not, in the foreseeable future, join the EMU must have a place in the European within a flexible community.

Within Manifest for a confederate Europe there are points to debate but it is strongly focused on EMU concerns and not all the items will find a consensus but it frames the debate on the future of the EU as it should be. That is as how to a achieve the extension of constitutional liberalism beyond the nation state.  

Privacy: your data

At the Liberal Democrats Autumn conference I helped organise an ALDES (Association of Liberal Democrat Engineers and Scientists)  discussion session on privacy and security titled "Your data, your choice" .  The motivation for the session was that:
Government, business and our personal lives are increasingly driven by our personal data. Credit card transactions, location data, and health records have the potential to improve products, provide insight for policy making, and detect security threats. But they also challenge our notions of privacy, intimacy and autonomy. How can results from privacy research be translated into policy?

The session was chaired by Richard Gomer, a researcher in Meaningful Consent. The panellists brought expertise from the areas of publishing, computer science, artificial intelligent and security

  • Yves-Alexandre de Montjoye (Data Scientist and privacy researcher at Imperial College London)
  • Luc Moreau (Professor of Computer Science at King’s College London)
  • Yogesh Patel (Chief Scientist at Callsign)
  • Leonie Mueck (Division Editor at PLOS ONE.)

There are steps individuals, as well as local and national governments, could take to protect privacy through regulation and law on the use personal data, education and digital rights. The intent is to pursue this topic with Liberal Reform and the Liberal Democrat Lawyers Association.
An important aspect of the discussion is the impact of algorithms with access to very large data sets of personal information. This was the topic addressed at the Royal Society discussion over the 2 day (30-31 October): "The growing ubiquity of algorithms in society: implications, impacts and innovations".

This session was almost dominated by legal considerations but served to underline the challenges to regulation and the rule of law that arise due to technical advance due to the availability of personal data, commutation power and algorithmic innovation.  Technology may also provide a defence, especially for those aspect of privacy that are close to data security. The formalisation of secrecy following the seminal work of Claude Shannon during WWII allows a definition of an aspect of privacy to be  formalised in a mathematically precise sense. This can be implemented to give some guarantee that the use of your personal data does not impact (or bounds the impact on) your privacy.