Overview

1 What is deep learning?

Artificial intelligence has surged into public consciousness, often accompanied by sweeping promises and dire warnings. This chapter cuts through the noise by situating deep learning within the broader landscape of AI and machine learning, clarifying what each term means and why deep learning has become so influential. It frames the reader’s role as a future practitioner who can distinguish genuine progress from hype, and it sets out to answer what deep learning has achieved, how significant those achievements are, and where the field is heading.

AI is presented as the effort to automate intellectual tasks, historically dominated by symbolic systems before shifting to machine learning, where models are trained on examples rather than programmed with rules. The chapter emphasizes representation learning: transforming raw data into forms that make tasks easier, and explains deep learning as stacking many such transformations in neural networks. It outlines how models learn by adjusting weights to minimize a loss via backpropagation, and why deep learning matters: it automates feature engineering (simplicity), scales with data and compute (scalability), and supports continual adaptation and reuse (versatility). It also introduces the rise of foundation models and generative AI, powered by self-supervised learning and prompting, which leverage vast unlabeled data to produce broadly useful capabilities.

The chapter surveys breakthroughs—from human-level perception and translation to code assistants, photorealistic image generation, improved recommendation, autonomous driving, and scientific and medical applications—while urging caution about short-term expectations. It distinguishes today’s systems as powerful cognitive automation rather than general intelligence, noting limits in adaptability and warning that hype cycles can trigger funding winters, as history shows. Although a correction to current exuberance is plausible, the core ideas and methods of deep learning are poised to endure and continue transforming workflows across domains.

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Machine learning: a new programming paradigm HTML: class=''small-image''
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A deep neural network for digit classification
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A neural network is parameterized by its weights.
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The loss score is used as a feedback signal to adjust the weights. HTML: class=''small-image''
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The promise of AI

Although we may have unrealistic short-term expectations for AI, the long-term picture is looking bright. We’re only getting started in applying deep learning to many important problems for which it could prove transformative, from medical diagnoses to digital assistants.

In 2017, in this very book, I wrote:

Right now, it may seem hard to believe that AI could have a large impact on our world, because it isn’t yet widely deployed – much as, back in 1995, it would have been difficult to believe in the future impact of the internet. Back then, most people didn’t see how the internet was relevant to them and how it was going to change their lives. The same is true for deep learning and AI today. But make no mistake: AI is coming. In a not-so-distant future, AI will be your assistant, even your friend; it will answer your questions, help educate your kids, and watch over your health. It will deliver your groceries to your door and drive you from point A to point B. It will be your interface to an increasingly complex and information-intensive world. And, even more important, AI will help humanity as a whole move forward, by assisting human scientists in new breakthrough discoveries across all scientific fields, from genomics to mathematics.

Fast-forward to 2024, most of these things have come either come true or are on the verge of coming true – and this is just the beginning.

  • Tens of millions of people are using AI chatbots like ChapGPT, Gemini, or Claude as assistants on a daily basis. In fact, question-answering and ''educating your kids'' (homework assistance) have turned out to be the top applications of these chatbots! AI is already their go-to interface to the world’s information.
  • Tens of thousands of people interact with AI ''friends'' in applications such as Character.ai
  • Fully autonomous driving is already deployed at scale in two cities: San Francisco and Phoenix. And those autonomous Waymo cars are powered by Keras models!
  • AI is making major strides towards helping accelerate science. The AlphaFold model from DeepMind is helping biologists predict protein structures with unprecedented accuracy. Renowned mathematician Terence Tao believes that by around 2026, AI could become a reliable co-author in mathematical research and other fields when used appropriately.

The AI revolution, once a distant vision, is now rapidly unfolding before our eyes. On the way, we may face a few setbacks and maybe even a new AI winter – in much the same way the internet industry was overhyped in 1998–1999 and suffered from a crash that dried up investment throughout the early 2000s. But we’ll get there eventually. AI will end up being applied to nearly every process that makes up our society and our daily lives, much like the internet is today.

Don’t believe the short-term hype, but do believe in the long-term vision. It may take a while for AI to be deployed to its true potential – a potential the full extent of which no one has yet dared to dream – but AI is coming, and it will transform our world in a fantastic way.

FAQ

What’s the difference between AI, machine learning, and deep learning?Artificial intelligence (AI) is the broad goal of automating intellectual tasks typically done by humans. Machine learning (ML) is a subfield of AI where systems learn rules from data instead of being explicitly programmed. Deep learning (DL) is a subfield of ML that learns many successive layers of representations using neural networks.
Why did symbolic AI and expert systems fall short for many real‑world problems?Symbolic AI relied on hand‑crafted rules and explicit knowledge bases. It worked for tightly defined, logical tasks (like chess) but proved brittle for fuzzy, high‑dimensional problems such as vision, speech, and translation. Machine learning supplanted it by learning directly from examples rather than relying on ever‑growing rule sets.
What does “learning representations” mean, and why does it matter?A representation is just another way to encode data so the task becomes easier. ML searches a predefined space of transformations (the hypothesis space) and uses feedback to pick those that bring inputs closer to desired outputs. Good representations turn hard problems into simpler ones that can be solved with straightforward rules.
What makes learning “deep” in deep learning?“Deep” refers to stacking many layers of learned transformations. Each layer distills information a bit more, forming hierarchical features. Shallow approaches typically learn only one or two layers, while modern deep networks may have tens or hundreds, all learned from data.
How does a neural network actually learn during training?Each layer has parameters called weights. A loss function measures how far predictions are from targets. An optimizer uses backpropagation to adjust weights to reduce loss. Starting from random weights, repeating this training loop over many examples gradually yields a model that maps inputs to targets well.
What makes deep learning especially impactful today?Deep learning combines:
  • Simplicity: It automates feature engineering, replacing complex pipelines with end‑to‑end models.
  • Scalability: It trains efficiently on GPUs/TPUs with mini‑batches and benefits from hardware advances.
  • Versatility and reusability: Trained models can be updated with more data and repurposed across tasks (e.g., foundation models).
What is generative AI, and how does self‑supervised learning fit in?Generative AI models (often large foundation models) learn to reconstruct or predict parts of their inputs (e.g., the next word, a denoised image). Because targets come from the input itself, they can use vast unlabeled datasets—this is self‑supervised learning. After training, they can be adapted to many tasks via prompting with little or no retraining.
What has deep learning achieved so far?Deep learning has driven breakthroughs across perception, language, generation, and control, including:
  • Versatile chatbots and coding assistants
  • Photorealistic image generation
  • Human‑level image, speech, and handwriting recognition
  • Much improved translation and text‑to‑speech
  • Autonomous driving deployments
  • Stronger recommender systems
  • Superhuman play in Go, Chess, and Poker
Should we believe the hype about imminent AGI and massive productivity booms?Approach bold claims with skepticism. Today’s systems are best viewed as cognitive automation—powerful tools that operationalize skills from data—not as autonomous intelligence. They excel where tasks are well specified or richly exemplified, but adaptability to the truly unknown remains a key gap.
Could there be another “AI winter,” and what might it look like?AI has seen two prior winters after hype cycles in the 1970s and late 1980s. A broad retreat seems less likely now, but some deflation is plausible because investment currently outpaces revenues. If a downturn comes, it may be mild: progress is real and widely useful, even if short‑term expectations prove overinflated.

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