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| public:t-709-aies-2024:aies-2024:intro [2024/08/22 10:14] – [Concepts] thorisson | public:t-709-aies-2024:aies-2024:intro [2024/11/04 15:11] (current) – [The Scientific Method: Classical Description] thorisson |
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| ===== SCIENTIFIC CONCEPTS ===== | ===== SCIENTIFIC CONCEPTS ===== |
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| ====Correlation, Knowledge, Causation==== | ====Correlation, Knowledge, Causation==== |
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| ==== Intelligence: A Natural Phenomenon==== | |
| | \\ Intelligence | A phenomenon encountered in nature. Intelligence is a phenomenon with good examples in the natural world, but may have more forms than the examples from nature. \\ The only one that //everyone// agrees on to call 'intelligent': **humans**. | | |
| | Natural Intelligence | Intelligence as it appears in nature. Some kinds of animals are considered "intelligent", or at least some behavior of some individuals of an animal species other than humans are deemed indicators of intelligence. | | |
| | Cognitive Science | The study of natural intelligence, in particular human (and that found in nature). | | |
| | Artificial Intelligence | The study of how to make intelligent machines. | | |
| | Intelligent Machines | Systems created by humans intended to display (some - but not all?) features required of beings encountered in nature. | | |
| | How to define 'intelligence' | Many definitions have been proposed. \\ See e.g.: [[http://www.vetta.org/documents/A-Collection-of-Definitions-of-Intelligence.pdf|A Collection of Definitions of Intelligence]] by Legg & Hutter. | | |
| | Definitions: a word of caution | We must be careful when it comes to definitions -- for any complex system there is a world of difference between a decent definition and //good accurate appropriate// definition. | | |
| | \\ \\ Related quote | Aaron Sloman says: "Some readers may hope for definitions of terms like information processing, mental process, consciousness, emotion, love. However, each of these denotes a large and ill-defined collection of capabilities or features. There is no definite collection of nec- essary or sufficient conditions (nor any disjunction of conjunctions) that can be used to define such terms." (From [[http://www.cs.bham.ac.uk/research/projects/cogaff/Sloman.kd.pdf|Architectural Requirements for Human-like Agents Both Natural and Artificial]] by A. Sloman) | | |
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| ====Historical Concepts==== | |
| | AI | In 1956 there was a workshop at Dartmouth College in the US where many of the field's founding fathers agreed on the term to user for their field, and outlined various topics to be studied within the field. | | |
| | GOFAI | "Good old-fashioned AI" is a term used nowadays to describe the first 20-30 years of research in the field. | | |
| | \\ Cybernetics | Going back to WWI the field of cybernetics claimed a scope that could easily be said to subsume AI. Many of the ideas associated with information technology came out of this melting pot, including ideas by von Neumann. However, cybernetics has since all but disappeared. Why? | | |
| | \\ GMI or AGI | "Artificial general intelligence" or "general machine intelligence": What we call the machine that we hope to build that could potentially surpass human intelligence at some point in the future -- a more holistic take on the phenomenon of intelligence than the present mainstream AI research would indicate. Will we succeed? Only time will tell. | | |
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| ==== Empirical Science (or just 'science') ==== | ==== Empirical Science (or just 'science') ==== |
| | Identification, description and formalization of phenomenon | 1. Observation and description of a phenomenon or group of phenomena. | | | Identification, description and formalization of phenomenon | 1. Observation and description of a phenomenon or group of phenomena. | |
| | Hypothesis, null-hypothesis | 2. Formulation of an hypothesis to explain the phenomena. In physics, the hypothesis often takes the form of a causal mechanism or a mathematical relation. | | | Hypothesis, null-hypothesis | 2. Formulation of an hypothesis to explain the phenomena. In physics, the hypothesis often takes the form of a causal mechanism or a mathematical relation. | |
| | Creation of experimental setup to test hypothesis | 3. Use of the hypothesis to predict the existence of other phenomena, or to predict quantitatively the results of new observations. | | | Creation of **experimental setup** to test hypothesis | 3. Use of the hypothesis to predict the existence of other phenomena, or to predict quantitatively the results of new observations. | |
| | Performance of experiment, collection and analysis of results | 4. Performance of experimental tests of the predictions by several independent experimenters and properly performed experiments. Basic assumption: Repeatability --- Can be repeated by anyone anywhere | | | **Perform experiment**, collect & analyze results | 4. Performance of experimental tests of the predictions by several independent experimenters and properly performed experiments. Basic assumption: Repeatability --- Can be repeated by anyone anywhere. | |
| | Repeatability requires formal framework | Detailed description, clear goals, clear (limited) scope, hence the formalities in their execution | | | Repeatability requires structured framework | Detailed description, clear goals, clear (limited) scope, hence the formalities in their execution. | |
| | Key idea: Comparsion | Baseline collected in same experimental setup without any other intervention by experimenter | | | Key idea: **Comparision** | Baseline collected in same experimental setup without any other intervention by experimenter | |
| | Key way of comparing | Experiments | | | Key way of comparing | Empirical experiments. | |
| | Bottom line | Scientific research is a //slow and expensive process//. \\ But it's the best one we've got (so far). \\ And it's completely worth it. | | | Bottom line | Scientific research is a //slow and expensive process//. \\ But it's the best one we've got (so far). \\ And it's completely worth it. | |
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| | Key idea: **Comparsion** | Baseline collected in same experimental setup without any other intervention by experimenter | | | Key idea: **Comparsion** | Baseline collected in same experimental setup without any other intervention by experimenter | |
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| | ==== Causation ==== |
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| | | What it is | A relation between entities in the physical world that allows us to achieve goals and predict events. | |
| | | Why it's important | The comparative experiment ("the scientific method") is based on the assumption that such relations exist, i.e. that the world has regularities. | |
| | | How it relates to logic | If causal relations are rules, and the world has regularity, then the world is rules-based. Reasoning is the method of following logic when working with rules. It means we can reason about the world. | |
| | | Types of \\ (basic) \\ causal relations | A->B & A->C : A causes B and C. \\ A->B->C : A causes B and B causes C \\ [A+B]->C : A and B together cause C. \\ A->C, B->C : Both A and B are sufficient to cause B. | |
| | | Time and Causation | The temporal relation between cause and effect is strict on time: Effects cannot happen before causes. | |
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| | ====Scientific Method: Independent of Topic==== |
| | | **Phenomenon** | The world is filled with "stuff". Anything is a "thing" - even "nothing" is a thing (a concept in our minds, which is represented as neural patterns and potential for behavior). We can group any arbitrary collection of things and call it a **phenomenon**. //Example: A rock. A mountain. A planet.// (If I say that I want to study //"thingamajigs"// - something you've never heard of - I will first have to list some of the major ways in which thingamajigs can be identified. In fact, this is a good idea anyway, so as to be clear and consistent about what it is that one is studying.) | |
| | | The scientific method is independent of topic... | One can study **any phenomenon** with the scientific method, including claims of telepathy; selection of topic is independent of method -- there is nothing inherently "unscientific" about studying any subject. (Close-mindedness //is//, however, very unscientific.) \\ In other words, given that science gets us the most reliable ("best") knowledge to build on at any time, we should take it seriously. But not so seriously as to exclude the possibility that it's wrong. (Because in fact we already know that **all** scientific knowledge is wrong -- i.e. every scientific theory to date has limits to its scope that we know of.) | |
| | | How can we trust our knowledge? | The scientific method is a **General Way of Producing Trustworthy Knowledge.** It is independent of topic. Therefore, it can also be used for AI systems. (In fact, it can easily be argued that something very similar to the scientific method is happening when humans learn cumulatively -- with a few caveats that we will carefully cover in this course.) | |
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| | ====Theories of the Scientific Method (Philosophy of Science) ==== |
| | | A scientific theory predicts | A good scientific theory can be used to predict (known and unknown) results. | |
| | | A scientific theory is a spotlight | A good scientific theory tells us where to look for interesting things; the more detailed the theory the more detailed should be its predictions and the more narrow its spotlight (specific suggestions for new investigations). | |
| | | A scientific theory can produce new hypotheses | A good scientific theory helps us do more experiments by being a source of hypothesis creation. | |
| | | A scientific theory provides control | A good scientific theory gives us control over the phenomenon it addresses that we would otherwise not have. | |
| | | A scientific theory **explains** ("tells a coherent story") | A good scientific theory explains how data is related. The more **completely** and the more **simply** it explains things, the better the theory. | |
| | | A scientific theory gives us the big picture | A good scientific theory relates together, in a coherent way, some part of the world -- in general the bigger the part, the better the theory. | |
| | | Occam's Razor | A good scientific theory cannot be simplified; it is the shortest and most accurate explanation of a phenomenon. Einstein is quoted as saying: "A theory should be as simple as possible, but not simpler". | |
| | | A scientific theory can be **disproven** | A scientific theory or hypothesis is a statement that is //disprovable//. To count as "scientific" a theory //must// be disprovable. For this there must exist some measures and actions that are //possible// (in theory, but better yet, practic) whose results would possibly - should the measurements come out a particular way - disprove the theory. \\ Applying this criterion strictly means that //all scientific theories to date have been disproven - i.e. proven incorrect.// \\ This is a //feature// of science (not a bug): Exposing the limits of our theories by demonstrating in which contexts they are incorrect allows us to come up with better theories. | |
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| | ==== Footnote: Fields of Research ==== |
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| | | Philosophy | A systematic investigation into any phenomenon. \\ Fundamental motivation: Deepened understanding of our place in the universe. \\ Fundamental driving principle: Human reasoning and creativity. \\ Fundamental organizing principle: Schools of thought; methods of reasoning. \\ //When you hardly know anything about a phenomenon, yet insist on getting to the bottom of it, philosophizing gets you started.// | |
| | | Induction | The cognitive act of generalizing from experience. //Example: Socrates is a man. Socrates died. Hence, all men will die.// | |
| | | Science | A systematic investigation into phenomena in the natural world susceptible to physical experimentation. \\ Fundamental motivation: Reliable knowledge of the world. \\ Fundamental driving principle: Induction. \\ Fundamental organizing principle: Controlled comparative experiment. \\ //When you embark on improving your understanding of a phenomenon with measurable/quantifiable variables, through comparative experiments, you are applying the **scientific method** ("doing science").// | |
| | | Engineering | Effort to construct things using relevant knowledge (often state-of-the-art scientific models/theories - see below), systematic methods, and relevant technology. \\ Fundamental motivation: Control of human environment. \\ Fundamental principle: Design. \\ Fundamental organizing principle: Methodical application of known procedures and methods. \\ //When you embark on changing or improving any aspect of your environment, working towards the implementation of a well-defined end product, through an application of best known practices, you are doing engineering.// | |
| | | Technology | Tools and techniques for getting things done. Fundamental principle: Composition, design, engineering. | |
| | | Deduction | The cognitive act of following preconceived rules to their inevitable implication. // Example: All men are mortal. Socrates is a man. Hence, Socrates is mortal. // | |
| | | Mathematics | A systematic study of quantity, numbers, patterns, and their relationships. Fundamental principle: Deduction. \\ //When you embark on clarifying the behavior and nature of quantifiable domains, using axiomatic rules and proofs, you are doing mathematics.// | |
| | | Causal Relations | A relation between two entities that makes one predictable from the other. // Examples: If I flip the light switch, the lights will shine. (Deduction) // If I want the light to shine, I can flip the light switch. (How to achieve a goal) | |
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| ===== INTELLIGENCE RESEARCH ===== | ===== INTELLIGENCE RESEARCH ===== |
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| ====Research on Intelligence==== | \\ |
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| | ==== Intelligence: A Natural Phenomenon==== |
| | | \\ Intelligence | A phenomenon encountered in nature. Intelligence is a phenomenon with good examples in the natural world, but may have more forms than the examples from nature. \\ The only one that //everyone// agrees on to call 'intelligent': **humans**. | |
| | | Natural Intelligence | Intelligence as it appears in nature. Some kinds of animals are considered "intelligent", or at least some behavior of some individuals of an animal species other than humans are deemed indicators of intelligence. | |
| | | Cognitive Science | The study of natural intelligence, in particular human (and that found in nature). | |
| | | Artificial Intelligence | The study of how to make intelligent machines. | |
| | | Intelligent Machines | Systems created by humans intended to display (some - but not all?) features required of beings encountered in nature. | |
| | | How to define 'intelligence' | Many definitions have been proposed. \\ See e.g.: [[http://www.vetta.org/documents/A-Collection-of-Definitions-of-Intelligence.pdf|A Collection of Definitions of Intelligence]] by Legg & Hutter. | |
| | | Definitions: a word of caution | We must be careful when it comes to definitions -- for any complex system there is a world of difference between a decent definition and //good accurate appropriate// definition. | |
| | | \\ \\ Related quote | Aaron Sloman says: "Some readers may hope for definitions of terms like information processing, mental process, consciousness, emotion, love. However, each of these denotes a large and ill-defined collection of capabilities or features. There is no definite collection of nec- essary or sufficient conditions (nor any disjunction of conjunctions) that can be used to define such terms." (From [[http://www.cs.bham.ac.uk/research/projects/cogaff/Sloman.kd.pdf|Architectural Requirements for Human-like Agents Both Natural and Artificial]] by A. Sloman) | |
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| | ====Researching Intelligence==== |
| | What is "intelligence"? | It is important to know what you're studying and researching! \\ ...A researcher selects their methods from their (premature) understanding of the phenomenon they'd like to 'figure out'. Without a good working definition, questions, methods and approach may be flawed. | | | What is "intelligence"? | It is important to know what you're studying and researching! \\ ...A researcher selects their methods from their (premature) understanding of the phenomenon they'd like to 'figure out'. Without a good working definition, questions, methods and approach may be flawed. | |
| | BUT: Beware of Premature Definitions | You cannot define something precisely until you understand it! \\ Premature precise definitions may be much worse than loose definitions or even bad-but-rough definitions: You are very likely to end up researching //something other// than what you set out to research. | | | BUT: Beware of Premature Definitions | You cannot define something precisely until you understand it! \\ Premature precise definitions may be much worse than loose definitions or even bad-but-rough definitions: You are very likely to end up researching //something other// than what you set out to research. | |
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| | ====Historical Concepts==== |
| | | AI | In 1956 there was a workshop at Dartmouth College in the US where many of the field's founding fathers agreed on the term to user for their field, and outlined various topics to be studied within the field. | |
| | | GOFAI | "Good old-fashioned AI" is a term used nowadays to describe the first 20-30 years of research in the field. | |
| | | \\ Cybernetics | Going back to WWI the field of cybernetics claimed a scope that could easily be said to subsume AI. Many of the ideas associated with information technology came out of this melting pot, including ideas by von Neumann. However, cybernetics has since all but disappeared. Why? | |
| | | \\ GMI or AGI | "Artificial general intelligence" or "general machine intelligence": What we call the machine that we hope to build that could potentially surpass human intelligence at some point in the future -- a more holistic take on the phenomenon of intelligence than the present mainstream AI research would indicate. Will we succeed? Only time will tell. | |
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| ====AI is a Broad Field of Research==== | ====AI is a Broad Field of Research==== |
| | \\ A Scientific Discipline | As an empirical scientific discipline, AI aims to figure out the general principles of how to implement the phenomenon of intelligence, including any subset thereof. \\ Does empiricism mean there is no theory? Absolutely not! Physics is an empirical science, yet is the scientific field that has the most advanced, accomplished theoretical foundation. \\ What would a proper theory of intelligence contain, if it existed? A //general// theory of intelligence would allow us to implement intelligence, or any subset thereof, successfully on first try, in a variety of formats meeting a variety of constraints. | | | \\ A Scientific Discipline | As an empirical scientific discipline, AI aims to figure out the general principles of how to implement the phenomenon of intelligence, including any subset thereof. \\ Does empiricism mean there is no theory? Absolutely not! Physics is an empirical science, yet is the scientific field that has the most advanced, accomplished theoretical foundation. \\ What would a proper theory of intelligence contain, if it existed? A //general// theory of intelligence would allow us to implement intelligence, or any subset thereof, successfully on first try, in a variety of formats meeting a variety of constraints. | |
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| ====Footnote on Terminology==== | |
| | Terminology is important! | The terms we use for phenomena must be shared to work as an effective means of communication. Obsessing about the definition of terms is a good thing! | | |
| | Beware of Definitions! | Obsessing over precise, definitive definitions of terms should not extend to the phenomena that the research targets: These are by definition not well understood. It is impossible to define something that is not understood! So beware of those who insist on such things. | | |
| | \\ Overloaded Terms | Many key terms in AI tend to be overloaded. Others are very unclear. Examples of the latter include: //intelligence, agent, concept, thought.// \\ Many terms have multiple meanings, e.g. reasoning, learning, complexity, generality, task, solution, proof. \\ Yet others are both unclear and polysemous, e.g. //consciousness//. \\ One source of the multiple meanings for terms is the tendency, in the beginning of a new research field, for founders to use common terms that originally refer to general concepts in nature, and which they intend to study, about the results of their own work. As time passes those concepts then begin to reference work done in the field, instead of their counterpart in nature. Examples include reinforcement learning (originally studied by Pavlov, Skinner, and others in psychology and biology), machine learning (learning in nature different from 'machine learning' in many ways), neural nets (artificial neural nets bear almost no relation to biological neural networks). \\ Needless to say, this regularly makes for some lively but more or less //pointless// debates on many subjects within the field of AI (and others, in fact, but especially AI). | | |
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| ==== Footnote on Science, Technology, Philosophy, Mathematics ==== | |
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| | Philosophy | A systematic investigation into any phenomenon. \\ Fundamental motivation: Deepened understanding of our place in the universe. \\ Fundamental driving principle: Human reasoning and creativity. \\ Fundamental organizing principle: Schools of thought; methods of reasoning. \\ //When you hardly know anything about a phenomenon, yet insist on getting to the bottom of it, philosophizing gets you started.// | | |
| | Induction | The cognitive act of generalizing from experience. //Example: Socrates is a man. Socrates died. Hence, all men will die.// | | |
| | Science | A systematic investigation into phenomena in the natural world susceptible to physical experimentation. \\ Fundamental motivation: Reliable knowledge of the world. \\ Fundamental driving principle: Induction. \\ Fundamental organizing principle: Controlled comparative experiment. \\ //When you embark on improving your understanding of a phenomenon with measurable/quantifiable variables, through comparative experiments, you are applying the **scientific method** ("doing science").// | | |
| | Engineering | Effort to construct things using relevant knowledge (often state-of-the-art scientific models/theories - see below), systematic methods, and relevant technology. \\ Fundamental motivation: Control of human environment. \\ Fundamental principle: Design. \\ Fundamental organizing principle: Methodical application of known procedures and methods. \\ //When you embark on changing or improving any aspect of your environment, working towards the implementation of a well-defined end product, through an application of best known practices, you are doing engineering.// | | |
| | Technology | Tools and techniques for getting things done. Fundamental principle: Composition, design, engineering. | | |
| | Deduction | The cognitive act of following preconceived rules to their inevitable implication. // Example: All men are mortal. Socrates is a man. Hence, Socrates is mortal. // | | |
| | Mathematics | A systematic study of quantity, numbers, patterns, and their relationships. Fundamental principle: Deduction. \\ //When you embark on clarifying the behavior and nature of quantifiable domains, using axiomatic rules and proofs, you are doing mathematics.// | | |
| | Causal Relations | A relation between two entities that makes one predictable from the other. // Examples: If I flip the light switch, the lights will shine. (Deduction) // If I want the light to shine, I can flip the light switch. (How to achieve a goal) | | |
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| ==== Causation ==== | |
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| | What it is | A relation between entities in the physical world that allows us to achieve goals and predict events. | | |
| | Why it's important | The comparative experiment ("the scientific method") is based on the assumption that such relations exist, i.e. that the world has regularities. | | |
| | How it relates to logic | If causal relations are rules, and the world has regularity, then the world is rules-based. Reasoning is the method of following logic when working with rules. It means we can reason about the world. | | |
| | Types of \\ (basic) \\ causal relations | A->B & A->C : A causes B and C. \\ A->B->C : A causes B and B causes C \\ [A+B]->C : A and B together cause C. \\ A->C, B->C : Both A and B are sufficient to cause B. | | |
| | Time and Causation | The temporal relation between cause and effect is strict on time: Effects cannot happen before causes. | | |
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| ====Reasoning==== | ====Reasoning==== |
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| | What are the main types? | Deduction: All men are mortal. Socrates is a man. Hence, Socrates is mortal \\ Abduction: How did this come about? (Sherlock Holmes) \\ Induction: What is the general rule? \\ Analogy: 'This' is like 'that' (in 'this' way). | | | What are the main types? | Deduction: All men are mortal. Socrates is a man. Hence, Socrates is mortal \\ Abduction: How did this come about? (Sherlock Holmes) \\ Induction: What is the general rule? \\ Analogy: 'This' is like 'that' (in 'this' way). | |
| | How is it used in science? | In empirical science to unearth the "rules of the universe". \\ In mathematics as axioms. \\ In philosophy as a way to construct arguments. \\ In computer science to write code. | | | How is it used in science? | In empirical science to unearth the "rules of the universe". \\ In mathematics as axioms. \\ In philosophy as a way to construct arguments. \\ In computer science to write code. | |
| | Why does it work? | Because the world's behavior is/seems rule-based. | | | Why does it work? | Because the world's behavior is/seems rule-based, some of which we have figured out to date (a very small part!). | |
| | | How is Reasoning relevant to AI & Ethics? | To manage rules requires reasoning. Intelligence makes models of the rules of the physical world. Therefore, reasoning is a necessary part of any intelligence. AI seeks to create machines that contain intelligence, thus AI must seek methods for machines that reason. Ethics can only make sense if it can be encoded in rules. | |
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| | ====Models in Science, Engineering & Math ==== |
| | | What it is | A model is a "cartoon" of a phenomenon -- an information structure that captures the most important (preferably all the important) aspects of a phenomenon in question. | |
| ====Theories of the Scientific Method (Philosophy of Science) ==== | | \\ The universe: \\ Nothing is given | How do we know that the sun will come up tomorrow? What evidence do we have? Can we prove it mathematically that the sun will come up tomorrow? \\ The only thing we know for sure is that we can perceive things in the world and that "I am here now". (This principle is most famously captured by Rene Descartes who wrote "I think, therefore I am".) \\ But since that perception is provided/generated by the same universe that we want to claim "exists" through those senses, using those grey cells, we cannot possibly know **for sure** what that really is, and hence whether it can be trusted. \\ Therefore, the universe is (and cannot be anything but) **non-axiomatic**. | |
| | A scientific theory predicts | A good scientific theory can be used to predict (known and unknown) results. | | | All scientific theories seek a model | No matter how explicit or implicit, all scientific theories are models of the world. \\ Good scientific theories tie a lot of knots, leaving few loose ends. Best known example: **E=mc^2** | |
| | A scientific theory is a spotlight | A good scientific theory tells us where to look for interesting things; the more detailed the theory the more detailed should be its predictions and the more narrow its spotlight (specific suggestions for new investigations). | | | Science vs. Mathematics | Mathematics is **axiomatic**: Some a-priori premises are (and must be) known and complete. \\ In contrast, science is non-axiomatic: We do not know the full set of rules that govern the universe, and we will never know. | |
| | A scientific theory can produce new hypotheses | A good scientific theory helps us do more experiments by being a source of hypothesis creation. | | | Science vs. Engineering | Science sees an undifferentiated world and looks for the model. \\ In engineering the model is given; the world is modified to behave like the model. | |
| | A scientific theory provides control | A good scientific theory gives us control over the phenomenon it addresses that we would otherwise not have. | | | \\ Science + Math | We strive to make scientific theories (models of the world) mathematical because of the //compactness, precision,// and //specificity// this can give us. However, it is not guaranteed solely through the use of math because //a theory must detail how it maps to the thing it is a model of//. If this is not done properly the math provides //no benefits//. \\ Mapping a model to its reference: A good scientist does it properly; a bad scientist does it sloppily; the wannabe ignores it happily. \\ Bottom line: Being mathematical is //no guarantee// for good science - it is neither necessary nor sufficient. | |
| | A scientific theory **explains** ("tells a coherent story") | A good scientific theory explains how data is related. The more **completely** and the more **simply** it explains things, the better the theory. | | | Science + Engineering + Math: The Holy Trinity | The three fields so defined support each other: Building better scientific models helps us engineer better; engineering better helps us build new tools for doing science better. Both are bootstrapped by philosophy and clarified through math. | |
| | A scientific theory gives us the big picture | A good scientific theory relates together, in a coherent way, some part of the world -- in general the bigger the part, the better the theory. | | | \\ Computer Science | A creative mix of empirical science, engineering and mathematics. \\ Direct testing of applications and programs; user studies. \\ Models and simulations. \\ Logical and mathematical proofs. | |
| | Occam's Razor | A good scientific theory cannot be simplified; it is the shortest and most accurate explanation of a phenomenon. Einstein is quoted as saying: "A theory should be as simple as possible, but not simpler". | | |
| | A scientific theory can be **disproven** | A scientific theory or hypothesis is a statement that is //disprovable//. To count as "scientific" a theory //must// be disprovable. For this there must exist some measures and actions that are //possible// (in theory, but better yet, practic) whose results would possibly - should the measurements come out a particular way - disprove the theory. \\ Applying this criterion strictly means that //all scientific theories to date have been disproven - i.e. proven incorrect.// \\ This is a //feature// of science (not a bug): Exposing the limits of our theories by demonstrating in which contexts they are incorrect allows us to come up with better theories. | | |
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| ====Scientific Method: Independent of Topic==== | |
| | **Phenomenon** | The world is filled with "stuff". Anything is a "thing" - even "nothing" is a thing (a concept in our minds, which is represented as neural patterns and potential for behavior). We can group any arbitrary collection of things and call it a **phenomenon**. //Example: A rock. A mountain. A planet.// (If I say that I want to study //"thingamajigs"// - something you've never heard of - I will first have to list some of the major ways in which thingamajigs can be identified. In fact, this is a good idea anyway, so as to be clear and consistent about what it is that one is studying.) | | |
| | The scientific method is independent of topic... | One can study **any phenomenon** with the scientific method, including claims of telepathy; selection of topic is independent of method -- there is nothing inherently "unscientific" about studying any subject. (Close-mindedness //is//, however, very unscientific.) \\ In other words, given that science gets us the most reliable ("best") knowledge to build on at any time, we should take it seriously. But not so seriously as to exclude the possibility that it's wrong. (Because in fact we already know that **all** scientific knowledge is wrong -- i.e. every scientific theory to date has limits to its scope that we know of.) | | |
| | How can we trust our knowledge? | The scientific method is a **General Way of Producing Trustworthy Knowledge.** It is independent of topic. Therefore, it can also be used for AI systems. (In fact, it can easily be argued that something very similar to the scientific method is happening when humans learn cumulatively -- with a few caveats that we will carefully cover in this course.) | | |
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| \\ | ====Footnote: Terminology==== |
| \\ | | Terminology is important! | The terms we use for phenomena must be shared to work as an effective means of communication. Obsessing about the definition of terms is a good thing! | |
| ====Models==== | | Beware of Definitions! | Obsessing over precise, definitive definitions of terms should not extend to the phenomena that the research targets: These are by definition not well understood. It is impossible to define something that is not understood! So beware of those who insist on such things. | |
| | What it is | A model is a "cartoon" of a phenomenon -- an information structure that captures the most important (preferably all the important) aspects of a phenomenon in question. | | | \\ Overloaded Terms | Many key terms in AI tend to be overloaded. Others are very unclear. Examples of the latter include: //intelligence, agent, concept, thought.// \\ Many terms have multiple meanings, e.g. reasoning, learning, complexity, generality, task, solution, proof. \\ Yet others are both unclear and polysemous, e.g. //consciousness//. \\ One source of the multiple meanings for terms is the tendency, in the beginning of a new research field, for founders to use common terms that originally refer to general concepts in nature, and which they intend to study, about the results of their own work. As time passes those concepts then begin to reference work done in the field, instead of their counterpart in nature. Examples include reinforcement learning (originally studied by Pavlov, Skinner, and others in psychology and biology), machine learning (learning in nature different from 'machine learning' in many ways), neural nets (artificial neural nets bear almost no relation to biological neural networks). \\ Needless to say, this regularly makes for some lively but more or less //pointless// debates on many subjects within the field of AI (and others, in fact, but especially AI). | |
| | All scientific theories present a model | No matter how explicit or implicit, all scientific theories are models of the world. //Best known example: E=mc^2// | | |
| | Science vs. Mathematics | Mathematics is **axiomatic**: Some a-priori premises are (and must be) assumed. \\ Science is non-axiomatic: We do not know the full set of rules that govern the universe, and we will never know. | | |
| | Science vs. Engineering | In science we look for the model; \\ in engineering we mold the world to behave like our model. | | |
| | \\ Science + Math | We strive to make scientific theories (models of the world) mathematical because of the //compactness, precision,// and //specificity// this can give us. However, it is not guaranteed solely through the use of math because //a model must detail how it maps to the thing it is a model of//. If this is not done properly the math provides //no benefits//. \\ Mapping a model to its reference: A good scientist does it properly; a bad scientist does it sloppily; the wannabe ignores it happily. \\ Bottom line: Being mathematical is //no guarantee// for good science - it is neither necessary nor sufficient. | | |
| | Science + Engineering + Math: The Holy Trinity | The three fields so defined support each other: Building better scientific models helps us engineer better; engineering better helps us build new tools for doing science better. Both are bootstrapped by philosophy and clarified through math. | | |
| | \\ The universe: Nothing is given | How do we know that the sun will come up tomorrow? What evidence do we have? Can we prove it mathematically that the sun will come up tomorrow? \\ The only thing we know for sure is that we can perceive things in the world and that "I am here now". (This principle is most famously captured by Rene Descartes who wrote "I think, therefore I am".) \\ But since that perception is provided/generated by the same universe that we want to claim "exists" through those senses, using those grey cells, we cannot possibly know **for sure** what that really is, and hence whether it can be trusted. \\ Therefore, the universe is (and cannot be anything but) **non-axiomatic**. | | |
| | \\ Computer Science | A creative mix of empirical science, engineering and mathematics. \\ Direct testing of applications and programs; user studies. \\ Models and simulations. \\ Logical and mathematical proofs. | | |
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