at Virtual Interaction with Machine Learning Course on Mar 9, 2021 [reveal]
Neil D. Lawrence, University of Sheffield

Abstract

The great AI fallacy is that we are building the first generation of automation that will adapt to humans rather than humans adapting to us. The more sobering reality is that we are building complex algorithmic decision making system that we are unable to explain. A FIT model is fair, interpretable and transparent. The machine learning community has placed effort into understanding how to improve interpretability into individual models, but the real challenge is how to build FIT systems. At the heart of the development of machine learning is the notion of separation of concerns, but this can obscure the real challenge which is responding to the human.

The Great AI Fallacy

There is a lot of variation in the use of the term artificial intelligence. I’m sometimes asked to define it, but depending on whether you’re speaking to a member of the public, a fellow machine learning researcher, or someone from the business community, the sense of the term differs.

However, underlying its use I’ve detected one disturbing trend. A trend I’m beginining to think of as “The Great AI Fallacy.”

The fallacy is associated with an implicit promise that is embedded in many statements about Artificial Intelligence. Artificial Intelligence, as it currently exists, is merely a form of automated decision making. The implicit promise of Artificial Intelligence is that it will be the first wave of automation where the machine adapts to the human, rather than the human adapting to the machine.

How else can we explain the suspension of sensible business judgment that is accompanying the hype surrounding AI?

This fallacy is particularly pernicious because there are serious benefits to society in deploying this new wave of data-driven automated decision making. But the AI Fallacy is causing us to suspend our calibrated skepticism that is needed to deploy these systems safely and efficiently.

The problem is compounded because many of the techniques that we’re speaking of were originally developed in academic laboratories in isolation from real-world deployment.

Separation of Concerns

To construct such complex systems an approach known as “separation of concerns” has been developed. The idea is that you architect your system, which consists of a large-scale complex task, into a set of simpler tasks. Each of these tasks is separately implemented. This is known as the decomposition of the task.

This is where Jonathan Zittrain’s beautifully named term “intellectual debt” rises to the fore. Separation of concerns enables the construction of a complex system. But who is concerned with the overall system?

• Technical debt is the inability to maintain your complex software system.

• Intellectual debt is the inability to explain your software system.

It is right there in our approach to software engineering. “Separation of concerns” means no one is concerned about the overall system itself.

The Mythical Man-month

However, when managing systems in production, you soon discover maintenance of a rapidly deployed system is not your only problem.

To deploy large and complex software systems, an engineering approach known as “separation of concerns” is taken. Frederick Brooks’ book “The Mythical Man-month” (Brooks, n.d.), has itself gained almost mythical status in the community. It focuses on what has become known as Brooks’ law “adding manpower to a late software project makes it later.”

Adding people (men or women!) to a project delays it because of the communication overhead required to get people up to speed.

Technical Consequence

Classical systems design assumes that the system is decomposable. That we can decompose the complex decision making process into distinct and independently designable parts. The composition of these parts gives us our final system.

Nicolas Negroponte, the original founder of MIT’s media lab used to write a column called ‘bits and atoms.’ This referred to the ability of information to effect movement of goods in the physical world. It is this interaction where machine learning technologies have the possibility to bring most benefit.

Information and Embodiment

Bandwidth Constrained Conversations

Embodiment factors imply that, in our communication between humans, what is not said is, perhaps, more important than what is said. To communicate with each other we need to have a model of who each of us are.

To aid this, in society, we are required to perform roles. Whether as a parent, a teacher, an employee or a boss. Each of these roles requires that we conform to certain standards of behaviour to facilitate communication between ourselves.

Control of self is vitally important to these communications.

The high availability of data available to humans undermines human-to-human communication channels by providing new routes to undermining our control of self.

The consequences between this mismatch of power and delivery are to be seen all around us. Because, just as driving an F1 car with bicycle wheels would be a fine art, so is the process of communication between humans.

If I have a thought and I wish to communicate it, I first of all need to have a model of what you think. I should think before I speak. When I speak, you may react. You have a model of who I am and what I was trying to say, and why I chose to say what I said. Now we begin this dance, where we are each trying to better understand each other and what we are saying. When it works, it is beautiful, but when misdeployed, just like a badly driven F1 car, there is a horrible crash, an argument.

Heider and Simmel (1944)

Fritz Heider and Marianne Simmel’s experiments with animated shapes from 1944 (Heider and Simmel, 1944). Our interpretation of these objects as showing motives and even emotion is a combination of our desire for narrative, a need for understanding of each other, and our ability to empathise. At one level, these are crudely drawn objects, but in another key way, the animator has communicated a story through simple facets such as their relative motions, their sizes and their actions. We apply our psychological representations to these faceless shapes in an effort to interpret their actions.

See also a recent review paper on Human Cooperation by Henrich and Muthukrishna (2021).

Computer Conversations

Similarly, we find it difficult to comprehend how computers are making decisions. Because they do so with more data than we can possibly imagine.

In many respects, this is not a problem, it’s a good thing. Computers and us are good at different things. But when we interact with a computer, when it acts in a different way to us, we need to remember why.

Just as the first step to getting along with other humans is understanding other humans, so it needs to be with getting along with our computers.

Embodiment factors explain why, at the same time, computers are so impressive in simulating our weather, but so poor at predicting our moods. Our complexity is greater than that of our weather, and each of us is tuned to read and respond to one another.

Their intelligence is different. It is based on very large quantities of data that we cannot absorb. Our computers don’t have a complex internal model of who we are. They don’t understand the human condition. They are not tuned to respond to us as we are to each other.

Embodiment factors encapsulate a profound thing about the nature of humans. Our locked in intelligence means that we are striving to communicate, so we put a lot of thought into what we’re communicating with. And if we’re communicating with something complex, we naturally anthropomorphize them.

We give our dogs, our cats and our cars human motivations. We do the same with our computers. We anthropomorphize them. We assume that they have the same objectives as us and the same constraints. They don’t.

This means, that when we worry about artificial intelligence, we worry about the wrong things. We fear computers that behave like more powerful versions of ourselves that will struggle to outcompete us.

In reality, the challenge is that our computers cannot be human enough. They cannot understand us with the depth we understand one another. They drop below our cognitive radar and operate outside our mental models.

The real danger is that computers don’t anthropomorphize. They’ll make decisions in isolation from us without our supervision, because they can’t communicate truly and deeply with us.

Artificial Intelligence and Data Science

Machine learning technologies have been the driver of two related, but distinct disciplines. The first is data science. Data science is an emerging field that arises from the fact that we now collect so much data by happenstance, rather than by experimental design. Classical statistics is the science of drawing conclusions from data, and to do so statistical experiments are carefully designed. In the modern era we collect so much data that there’s a desire to draw inferences directly from the data.

As well as machine learning, the field of data science draws from statistics, cloud computing, data storage (e.g. streaming data), visualization and data mining.

In contrast, artificial intelligence technologies typically focus on emulating some form of human behaviour, such as understanding an image, or some speech, or translating text from one form to another. The recent advances in artifcial intelligence have come from machine learning providing the automation. But in contrast to data science, in artifcial intelligence the data is normally collected with the specific task in mind. In this sense it has strong relations to classical statistics.

Classically artificial intelligence worried more about logic and planning and focussed less on data driven decision making. Modern machine learning owes more to the field of Cybernetics (Wiener, 1948) than artificial intelligence. Related fields include robotics, speech recognition, language understanding and computer vision.

There are strong overlaps between the fields, the wide availability of data by happenstance makes it easier to collect data for designing AI systems. These relations are coming through wide availability of sensing technologies that are interconnected by celluar networks, WiFi and the internet. This phenomenon is sometimes known as the Internet of Things, but this feels like a dangerous misnomer. We must never forget that we are interconnecting people, not things.

Convention for the Protection of Individuals with regard to Automatic Processing of Personal Data (1981/1/28)

Machine Learning Systems Design

The challenges of integrating different machine learning components into a whole that acts effectively as a system seem unresolved. In software engineering, separating parts of a system in this way is known as component-based software engineering. The core idea is that the different parts of the system can be independently designed according to a sub-specfication. This is sometimes known as separation of concerns. However, once the components are machine learning based, tighter coupling becomes a side effect of the learned nature of the system. For example if a driverless car’s detection of cyclist is dependent on its detection of the road surface, a change in the road surface detection algorithm will have downstream effects on the cyclist detection. Even if the road detection system has been improved by objective measures, the cyclist detection system may have become sensitive to the foibles of the previous version of road detection and will need to be retrained.

Most of our experience with deployment relies on some approximation to the component based model, this is also important for verification of the system. If the components of the system can be verified then the composed system can also, potentially, be verified.

Question Mark Emails

One challenge at Amazon was what I call the “L4 to Q4 problem.” The issue when an graduate engineer (Level 4 in Amazon terminology) makes a change to the code base that has a detrimental effect but we only discover it when the 4th Quarter results are released (Q4).

The challenge in explaining what went wrong is a challenge in intellectual debt.

Intellectual Debt

In computer systems the concept of technical debt has been surfaced by authors including Sculley et al. (2015). It is an important concept, that I think is somewhat hidden from the academic community, because it is a phenomenon that occurs when a computer software system is deployed.

FIT Models to FIT Systems

Zittrain points out the challenge around the lack of interpretability of individual ML models as the origin of intellectual debt. In machine learning I refer to work in this area as fairness, interpretability and transparency or FIT models. To an extent I agree with Zittrain, but if we understand the context and purpose of the decision making, I believe this is readily put right by the correct monitoring and retraining regime around the model. A concept I refer to as “progression testing.” Indeed, the best teams do this at the moment, and their failure to do it feels more of a matter of technical debt rather than intellectual, because arguably it is a maintenance task rather than an explanation task. After all, we have good statistical tools for interpreting individual models and decisions when we have the context. We can linearise around the operating point, we can perform counterfactual tests on the model. We can build empirical validation sets that explore fairness or accuracy of the model.

So, this is where, my understanding of intellectual debt in ML systems departs, I believe from John Zittrain’s. The long-term challenge is not in the individual model. We have excellent statistical tools for validating what any individual model, the long-term challenge is the complex interaction between different components in the decomposed system, where the original intent of each component has been forgotten (except perhaps by Lancelot) and each service has been repurposed. We need to move from FIT models to FIT systems.

How to address these challenges? With collaborators I’ve been working towards a solution that contains broadly two parts. The first part is what we refer to as “Data-Oriented Architectures.” The second part is “meta modelling,” machine learning techniques that help us model the models.

An example of a complex decision making system might be an automated buying system. In such a system, the idea is to match demand for products to supply of products.

The matching of demand and supply is a repetetive theme for decision making systems. Not only does it occur in automated buying, but also in the allocation of drivers to riders in a ride sharing system. Or in the allocation of compute resource to users in a cloud system.

The components of any of these system include: predictions of the demand for the product, or the drivers or the compute. Then predictions of the supply. Decisions are then made for how much material to keep in stock, or how many drivers to have on the road, or how much computer capacity to have in your data centres. These decisions have cost implications. The optimal amount of product will depend on the cost of making it available. For a buying system this is the storage costs.

Decisions are made on the basis of the supply and demand to make new orders, to encourage more drivers to come into the system or to build new data centers or rent more computational power.

Monolithic System

The classical approach to building these systems was a ‘monolithic system.’ Built in a similar way to the successful applicaitons software such as Excel or Word, or large operating systems, a single code base was constructed. The complexity of such code bases run to many lines.

In practice, shared dynamically linked libraries may be used for aspects such as user interface, or networking, but the software often has many millions of lines of code. For example, the Microsoft Office suite is said to contain over 30 millions of lines of code.

Service Oriented Architecture

Such software is not only difficult to develop, it is difficult to scale when computation demands increase. Amazon’s original website software (called Obidos) was a monolithic design but by the early noughties it was becoming difficult to sustain and maintain. The software was phased out in 2006 to be replaced by a modularized software known as a ‘service oriented architecture.’

In Service Oriented Architecture, or “Software as a Service” the idea is that code bases are modularized and communicate with one another using network requests. A standard approach is to use a REST API. So, rather than a single monolithic code base, the code is developed with individual services that handle the different requests.

This is the landscape we now find ourselves in with regard to software development. In practice, each of these services is often ‘owned’ and maintained by an individual team. The team is judged by the quality of their service provision. They work to detailed specifications on what their service should output, what its availability should be and other objectives like speed of response. This allows for conditional independence between teams and for faster development.

The same model we consider for buying, can also be considered in the case of, for example, a banking application. In a typical banking application, we receive loan requests from customers. For an individual customer, before making a loan, the bank may wish to make a forecast around their costs (expenditures on food, housing, entertainment etc) and their income (salary, rental income etc). These forecasts would inform the conditions of the loan. For example how much the bank is willing to lend, and under what interest rates and repayment conditions. These terms will be based on previous experience of loaning, but also constrained by regulatory conditions often imposed by a financial regulator.

In many regulatory environments, the bank will be restricted in terms of what information they are allowed to use in dictating loan terms. For example, with in the EU there are prohibited characteristics such as race, gender, sexuality, religion and health status which cannot be used (even indirectly) for making the loan. Along with stipulating these characteristics, the badly-named GDPR1 also gives particular stipulations for rights individuals have for explanation around consequential decisions, such as obtaining a loan.

The challenge of Intellectual Debt means that it’s possible for a bank to produce an automated loan decision system, which even the bank itself doesn’t understand, which makes it rather hard to conform to the intent of the GDPR which requires the bank to explain to customers the reasoning behind decisions based on personal data.

How the GDPR May Help

Early reactions to the General Data Protection Regulation by companies seem to have been fairly wary, but if we view the principles outlined in the GDPR as good practice, rather than regulation, it feels like companies can only improve their internal data ecosystems by conforming to the GDPR. For this reason, I like to think of the initials as standing for “Good Data Practice Rules” rather than General Data Protection Regulation. In particular, the term “data protection” is a misnomer, and indeed the earliest data protection directive from the EU (from 1981) refers to the protection of individuals with regard to the automatic processing of personal data, which is a much better sense of the term.

If we think of the legislation as protecting individuals, and we note that it seeks, and instead of viewing it as regulation, we view it as “Wouldn’t it be good if …,” e.g. in respect to the “right to an explanation”, we might suggest: “Wouldn’t it be good if we could explain why our automated decision making system made a particular decison.” That seems like good practice for an organization’s automated decision making systems.

Similarly, with regard to data minimization principles. Retaining the minimum amount of personal data needed to drive decisions could well lead to better decision making as it causes us to become intentional about which data is used rather than the sloppier thinking that “more is better” encourages. Particularly when we consider that to be truly useful data has to be cleaned and maintained.

If GDPR is truly reflecting the interests of individuals, then it is also reflecting the interests of consumers, patients, users etc, each of whom make use of these systems. For any company that is customer facing, or any service that prides itself on the quality of its delivery to those individuals, “good data practice” should become part of the DNA of the organization.

Emulation

A statistical emulator is a data-driven model that learns about the underlying simulation. Importantly, learns with uncertainty, so it ‘knows what it doesn’t know.’ In practice, we can call the emulator in place of the simulator. If the emulator ‘doesn’t know,’ it can call the simulator for the answer.

As well as reconstructing an individual simulator, the emulator can calibrate the simulation to the real world, by monitoring differences between the simulator and real data. This allows the emulator to characterise where the simulation can be relied on, i.e. we can validate the simulator.

Similarly, the emulator can adjudicate between simulations. This is known as multi-fidelity emulation. The emulator characterizes which emulations perform well where.

If all this modelling is done with judiscious handling of the uncertainty, the computational doubt, then the emulator can assist in desciding what experiment should be run next to aid a decision: should we run a simulator, in which case which one, or should we attempt to acquire data from a real world intervention.

Bayesian Inference by Rejection Sampling

One view of Bayesian inference is to assume we are given a mechanism for generating samples, where we assume that mechanism is representing on accurate view on the way we believe the world works.

This mechanism is known as our prior belief.

We combine our prior belief with our observations of the real world by discarding all those samples that are inconsistent with our prior. The likelihood defines mathematically what we mean by inconsistent with the prior. The higher the noise level in the likelihood, the looser the notion of consistent.

The samples that remain are considered to be samples from the posterior.

This approach to Bayesian inference is closely related to two sampling techniques known as rejection sampling and importance sampling. It is realized in practice in an approach known as approximate Bayesian computation (ABC) or likelihood-free inference.

In practice, the algorithm is often too slow to be practical, because most samples will be inconsistent with the data and as a result the mechanism has to be operated many times to obtain a few posterior samples.

However, in the Gaussian process case, when the likelihood also assumes Gaussian noise, we can operate this mechanism mathematically, and obtain the posterior density analytically. This is the benefit of Gaussian processes.

First we will load in two python functions for computing the covariance function.

Next we sample from a multivariate normal density (a multivariate Gaussian), using the covariance function as the covariance matrix.

plot.rejection_samples(kernel=kernel,
diagrams='../slides/diagrams/gp')

Deep Emulation

As a solution we can use of emulators. When constructing an ML system, software engineers, ML engineers, economists and operations researchers are explicitly defining relationships between variables of interest in the system. That implicitly defines a joint distribution, $p(\mathbf{ y}^*, \mathbf{ y})$. In a decomposable system any sub-component may be defined as $p(\mathbf{ y}_\mathbf{i}|\mathbf{ y}_\mathbf{j})$ where $\mathbf{ y}_\mathbf{i}$ and $\mathbf{ y}_\mathbf{j}$ represent sub-sets of the full set of variables $\left\{\mathbf{ y}^*, \mathbf{ y}\right\}$. In those cases where the relationship is deterministic, the probability density would collapse to a vector-valued deterministic function, $\mathbf{ f}_\mathbf{i}\left(\mathbf{ y}_\mathbf{j}\right)$.

Inter-variable relationships could be defined by, for example a neural network (machine learning), an integer program (operational research), or a simulation (supply chain). This makes probabilistic inference in this joint density for real world systems is either very hard or impossible.

Emulation is a form of meta-modelling: we construct a model of the model. We can define the joint density of an emulator as $s(\mathbf{ y}*, \mathbf{ y})$, but if this probability density is to be an accurate representation of our system, it is likely to be prohibitively complex. Current practice is to design an emulator to deal with a specific question. This is done by fitting an ML model to a simulation from the the appropriate conditional distribution, $p(\mathbf{ y}_\mathbf{i}|\mathbf{ y}_\mathbf{j})$, which is intractable. The emulator provides an approximated answer of the form $s(\mathbf{ y}_\mathbf{i}|\mathbf{ y}_\mathbf{j})$. Critically, an emulator should incorporate its uncertainty about its approximation. So the emulator answer will be less certain than direct access to the conditional $p(\mathbf{ y}_i|\mathbf{ y}_j)$, but it may be sufficiently confident to act upon. Careful design of emulators to answer a given question leads to efficient diagnostics and understanding of the system. But in a complex interacting system an exponentially increasing number of questions can be asked. This calls for a system of automated construction of emulators which selects the right structure and redeploys the emulator as necessary. Rapid redeployment of emulators could exploit pre-existing emulators through transfer learning.

Automatically deploying these families of emulators for full system understanding is highly ambitious. It requires advances in engineering infrastructure, emulation and Bayesian optimization. However, the intermediate steps of developing this architecture also allow for automated monitoring of system accuracy and fairness. This facilitates AutoML on a component-wise basis which we can see as a simple implementation of AutoAI. The proposal is structured so that despite its technical ambition there is a smooth ramp of benefits to be derived across the programme of work.

In Applied Mathematics, the field studying these techniques is known as uncertainty quantification. The new challenge is the automation of emulator creation on demand to answer questions of interest and facilitate the system design, i.e. AutoAI through BSO.

At design stage, any particular AI task could be decomposed in multiple ways. Bayesian system optimization will assist both in determining the large-scale system design through exploring different decompositions and in refinement of the deployed system.

So far, most work on emulators has focussed on emulating a single component. Automated deployment and maintenance of ML systems requires networks of emulators that can be deployed and redeployed on demand depending on the particular question of interest. Therefore, the technical innovations we require are in the mathematical composition of emulator models (Damianou and Lawrence, 2013; Perdikaris et al., 2017). Different chains of emulators will need to be rapidly composed to make predictions of downstream performance. This requires rapid retraining of emulators and propagation of uncertainty through the emulation pipeline a process we call deep emulation.

Recomposing the ML system requires structural learning of the network. By parameterizing covariance functions appropriately this can be done through Gaussian processes (e.g. (Damianou et al., n.d.)), but one could also consider Bayesian neural networks and other generative models, e.g. Generative Adversarial Networks (Goodfellow et al., 2014).

Conclusion

Today’s artificial intelligence is fundamentally Machine Learning Systems design, but the systems we are building will not fulfill the promises we are making for them. We are not yet ready to deploy automation in fully uncontrolled environments. Until we modify our approaches we will not be able to deliver on the promise. Until then, monitoring and upadate of deployed systems will be key to practical and safe AI.

Thanks!

For more information on these subjects and more you might want to check the following resources.

References

Brooks, F., n.d. The mythical man-month. Addison-Wesley.
Damianou, A., Ek, C.H., Titsias, M.K., Lawrence, N.D., n.d. Manifold relevance determination.
Damianou, A., Lawrence, N.D., 2013. Deep Gaussian processes. pp. 207–215.
Goodfellow, I., Pouget-Abadie, J., Mirza, M., Xu, B., Warde-Farley, D., Ozair, S., Courville, A., Bengio, Y., 2014. Generative adversarial nets, in: Ghahramani, Z., Welling, M., Cortes, C., Lawrence, N.D., Weinberger, K.Q. (Eds.), Advances in Neural Information Processing Systems 27. Curran Associates, Inc., pp. 2672–2680.
Heider, F., Simmel, M., 1944. An experimental study of apparent behavior. The American Journal of Psychology 57, 243–259.
Henrich, J., Muthukrishna, M., 2021. The origins and psychology of human cooperation. Annual Review of Psychology 72, 207–240. https://doi.org/10.1146/annurev-psych-081920-042106
Perdikaris, P., Raissi, M., Damianou, A., Lawrence, N.D., Karnidakis, G.E., 2017. Nonlinear information fusion algorithms for data-efficient multi-fidelity modelling. Proc. R. Soc. A 473. https://doi.org/10.1098/rspa.2016.0751
Sculley, D., Holt, G., Golovin, D., Davydov, E., Phillips, T., Ebner, D., Chaudhary, V., Young, M., Crespo, J.-F., Dennison, D., 2015. Hidden technical debt in machine learning systems, in: Cortes, C., Lawrence, N.D., Lee, D.D., Sugiyama, M., Garnett, R. (Eds.), Advances in Neural Information Processing Systems 28. Curran Associates, Inc., pp. 2503–2511.
Wiener, N., 1948. Cybernetics: Control and communication in the animal and the machine. MIT Press, Cambridge, MA.

1. The GDPR is “General Data Protection Regulation” but it does not ‘protect data’ it ‘protects individuals’ with regard to decision making based on their personal data. The misnomer data-protection is unfortunate, a better way of viewing this legislation is “personal data rights” legislation.↩︎