Download document

Midterm Review
25 February 2008
What does a Computer Do Well?

Intelligence amplifier




Does repetitive tasks quickly and correctly



amplifies our ability to perform mental activities
“power tools” for the mind
Can process much more information
Check things more quickly
Removes people from boring tasks
Manipulates forms and data
What a Computer Does





Very simple machine: executes exactly what it is told
Executes instructions that define algorithms
Instructions stored in the computer are the software
 We can change them
Instructions deal with holders of data, not the data
itself
 Gives them the ability to deal with any data
Makes computers the most adaptable tool
Logical organization of computer system
CPU
Inputs
programs
data
Outputs
Memory
information
Programs &
Data/info in use now
Storage
LOTS of programs and data files stored
here
What is stored in the Computer?

Bits: ones and zeroes


Why? Easy to build
To make managing information easier, stored
in fixed size packets:

Bytes (8 bits), Half words, Words, ...
Storing Numbers:
Binary Positional System
8 4 2 1
0
0
0
0
0
0
0
0
0
1
0
0
1
1
0
0
1
0
1
0
=
0
=
1
=
2
=
3
=
4
1=
0
Data Types


Computer doesn’t know what the bits
represents or what format is being used
Computer assumes that the instructions know
the format of the data
Data Types

Numbers: integers and floating point numbers (scientific
notation)


Text: Unicode, double byte




Languages and symbols (Word insert symbol)
Pictures: pixels


Why do we need floating point numbers?
A very fine needlepoint
How to represent color?
Sound: different formats
Instructions
The Internet

What is it?




The infrastructure that connects identified computers
Links = the wires
Routers = the boxes that connect them
World Wide Web


Computers that contain information to be shared
Servers
How Networking Works

Need to know where to go and how to et there



Who identified by IP address

Every machine that is connected to the network has one
Routers know how to get there
But IP addresses aren’t user friendly


Give names instead
Domain Name Server does the mapping
Benefits and Risks

Most benefits are obvious






Productivity tools
Medicine
Education
Assistive technologies
…
But with benefits come risks…
Risks




Software failures
Networking breaches
Technology often evolves faster than our
ability to handle
Try to do everything with technology
Software Problems

Usability


Bad Design
Reliability

Programming Mistakes


Why is it so hard?
Why can’t we get it right?
Is this a Problem?
“Our civilization runs on software,
yet the art of creating it
continues to be a dark mystery,
even to the experts.
And the greater our ambitions, the
more spectacular we seem to fail.”
Scott Rosenberg, “Dreaming in Code”
Characteristics of a Useful Tool

Help you achieve WHAT you want, in less
time, with minimal effort….

Do ALL that you need …

Easy to learn (intuitive)

Easy to remember

Standardized
Why are bugs hard to find?

The error can appear in another program


Device drivers, memory management
The error may only occur occasionally

May require multiple conditions to occur
User Interface Bug


Afghanistan War (December 2001)
 Friendly fire kills 3 injures 20 when satellite-guided
bomb landed on a battalion command post
Use of GPS Receiver to determine coordinators
 Change battery
 Own location came up, not the one that had been
entered
Lots of Examples of Software Bugs



Therac 25
FBI Virtual Case File
Rocket launches, ...
Networking Problems




Data can be read
Data can be lost
Data can be changed
Data can be sent to someone else

People assume they know who owns the site
Easy-to-discuss RISKS
• Technostress
• Multitasking
• Sidetracking
Kling Analogy


First viewed as a clean technology
Easy to See the Benefits





Easy to identify
Want to see them
Is it possible to identify every side effect or
impact?
What about unintentional side effects?
Ethical responsibility to try to look at
consequences
Role of Ethics




Framework to evaluate and reason
Philosophical study of morality
Ethical issues must be voluntary and related to
morality
Fundamental purpose of morality: to advance
the common good

Core values
Ethical Theories

Ethical relativism



Individual (or subjective)
Cultural
Normative ethical theories

Deontological



Kantianism
Contractualism
Teleological


Utilitarianism
Just consequentialism
Normative Ethical Theories

Deontological: based on the sense of duty


Right because of the act
Teleological: based on the result

Right because of the result
Deontological Theory

What is it?



Based on our duties and responsibilities
Actions are fundamentally right or wrong
Examples


1724-1804
Kantianism (Kant)
Contractualism (Hobbes, Rousseau)
1588-1679
1712-1788
Kantianism: Ethics of Duty

Duty as freely imposing obligation on one’s
own self


Duty is internal
We impose duty on ourselves
Kant’s Categorical Imperatives


Universality: “Always act in such a way
that the maxim of your action can be willed
as a universal law of humanity.”
Respect: “Always treat humanity, whether
in yourself or in other people, as an end in
itself and never as a mere means.”
Strengths of Kantianism



Rational
Produces universal moral guidelines
Treats all people as moral equals
Strengths and Criticisms

Strengths




Rational
Produces universal moral guidelines
Treats all people as moral equals
Criticisms




Moral minimalism: requirements are not heartfelt
Moral alienation: alienated from feelings
No way to resolve conflict between rules
Allows no exceptions
Contractualism


Social Contract Theory: duty not to interfere
with others’ rights
Morality consists in the set of rules, governing
how people are to treat one another, that
rational people will agree to accept, for their
mutual benefit, on the condition that others
follow those rules as well.
James Rachel, The Elements of Moral Philosophy
Rawls’s Principles of Justice


Each person may claim basic rights and 1921-2002
liberties as long as these claims are consistent
with everyone else having a claim to the same
rights
Social and economic inequalities must


Be associated with positions in society to which
everyone has an equal opportunity
Be of the greatest benefit to the least-advantaged
Strengths and Criticisms

Strengths






Framed in terms of rights
Explains acting out of self-interest when there is
no common agreement
Provides framework for moral issues dealing with
government
Criticisms
Doesn’t address actions that can be characterized
multiple ways
Doesn’t address conflicting rights
Term Projects

A thesis needs to be a statement that you are
willing to defend


It should not be a black or white statement
Rework for Monday
Teleological Theory

What is it?


Something is good based on its consequences
Primary example: Utilitarianism

Jeremy Bentham

John Stuart Mill
1748-1832
1806-1873
Utilitarianism


Greatest Happiness Principle
Compute the costs and benefits


Simple calculation: do positives outweigh the
negatives?
Two forms


Act – judge the consequence of a specific act
Rule – judge the consequence of the generalized
rule
Strengths and Criticisms


Strengths
 Focus on happiness
 Down to earth
 Appeals to many people
 Comprehensive
Criticisms
 Ignores our sense of duty
 Range of effects that one must consider
 Requires that we balance very different aspects
 Unjust distribution of good results
Just Consequentialism


James Moor (Dartmouth)
Consider consequences of action… but
combine w/deontological ideals


Consider duties, rights, and justice
Protect against unnecessary harm (suffering),
where harm = loss of core values

life, happiness, abilities, security, knowledge, freedom,
opportunities, resources
Applying Just Consequentialism

A decision or action is ethical if

It does not cause any unnecessary harm to
individuals and groups

Supports individual rights

Fulfills duties
Beyond Ethics

Regulators in Physical Space (Lessig)




Law (sanctions)
Social norms (behavior)
Market (cost)
Architecture (self-enforcement)