Aristotle and the art
of software development
Jonathan Dahl
http://tumblon.com (work)
http://zencoder.tv (product)
http://railspikes.com (blog)
Friday, September 18, 2009

Or: what does Athens have to
do with Silicon Valley?
Jonathan Dahl
http://tumblon.com (work)
http://zencoder.tv (product)
http://railspikes.com (blog)
Friday, September 18, 2009

Athens Silicon Valley
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Ethics.
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G
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PG
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PG-13
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R
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Ethics.
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What makes a good programmer?
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What makes a good programmer?
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What makes a good programmer?
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Anatomy of an action
Act - Effect
Actor
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Deontology (Kant)
Act - Effect
Actor
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Utilitarianism (Mill)
Act - Effect
Actor
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Virtue (Aristotle)
Act - Effect
Actor
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Downsides
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Symptoms
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What kind of Agile?
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What language?
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Immanuel Kant
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Königsberg
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deontology
duty
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Principles
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Categorical Imperative
Act only according to that maxim by
which you can at the same time will that
it should become a universal law
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Deontological
software development
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Don’t Repeat Yourself
100% Test Coverage
Write readable code
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Act - Effect
Actor
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Process - Outcome
Participants
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Determine the right process
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(Determine the right principles)
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Stick to the rules
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“You have to follow every aspect of
the process for it to work”
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Follow the rules, even when you
don’t think you’ll like the outcome
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“This is just the way things are
done”
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Ever-growing rules
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XP Rules
1.User stories are written. 16.The customer is always available.
2.Release planning creates the schedule. 17.Code must be written to agreed standards.
3.Make frequent small releases. 18.Code the unit test first.
4.The Project Velocity is measured. 19.All production code is pair programmed.
5.The project is divided into iterations. 20.Only one pair integrates code at a time.
6.Iteration planning starts each iteration. 21.Integrate often.
7.Move people around. 22.Use collective code ownership.
8.A stand-up meeting starts each day. 23.Leave optimization till last.
9.Fix XP when it breaks. 24.No overtime.
10.Simplicity. 25.All code must have unit tests.
11.Choose a system metaphor. 26.All code must pass all unit tests before it can
12.Use CRC cards for design sessions. be released.
13.Create spike solutions to reduce risk. 27.When a bug is found tests are created.
14.No functionality is added early. 28.Acceptance tests are run often and the
15.Refactor whenever and wherever score is published.
possible.
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Don’t Repeat Yourself
Write clear, understandable code
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development:
adapter: mysql
encoding: utf8
database: app_development
username: root
password:
test:
adapter: mysql
encoding: utf8
database: app_test
username: root
password:
production:
adapter: mysql
encoding: utf8
database: app_production
username: user
password: password
Friday, September 18, 2009

standard:
adapter: mysql
encoding: utf8
local:
username: root
password:
development:
<<: *standard
<<: *local
database: app_development
test:
<<: *standard
<<: *local
database: app_test
production:
<<: *standard
database: app_production
username: user
password: password
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<% local_password = "" -%>
<% local_user = "root" -%>
<% [{:name => "development", :user => local_user, :password => local_password},
{:name => "test", :user => local_user, :password => local_password},
{:name => "production", :user => "user", :password => "password"}
].each do |environment| -%>
<%= environment[:name] %>
adapter: mysql
encoding: utf8
database: app_<%= environment[:name] %>
username: <%= environment[:user] %>
password: <%= environment[:password] %>
<% end -%>
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What kind of agile?
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Certification
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John Stuart Mill
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John Stuart Mill
Opposed slavery
Favored women’s suffrage
Free markets
(...with proper regulation)
Animal rights
Environmentalism
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John Stuart Mill
Opposed slavery
Favored women’s suffrage
Free markets
(...with proper regulation)
Animal rights
Environmentalism
...way before these things were cool
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Utilitarianism
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Greatest good
for the greatest number
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The ends justify the means
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Utilitarian
software development
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Act - Effect
Actor
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Process - Outcome
Participants
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Driven by experience
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Ad hoc
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Results-oriented
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Willing to compromise
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“Just get it done”
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“Doesn’t have to be pretty”
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Short term vs. long term
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What kind of agile?
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No Process
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Lisp vs. Perl
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Act - Effect
Actor
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Philosophy
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Philosophy
Ethics
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Philosophy
Ethics
Politics
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Philosophy
Ethics
Politics
Rhetoric
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Philosophy
Ethics
Politics
Rhetoric
Aesthetics
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Philosophy
Ethics
Politics
Rhetoric
Aesthetics
Psychology
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Philosophy
Ethics
Politics
Rhetoric
Aesthetics
Psychology
Biology
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Philosophy
Ethics
Politics
Rhetoric
Aesthetics
Psychology
Biology
Physics
Friday, September 18, 2009

Philosophy
Ethics
Politics
Rhetoric
Aesthetics
Psychology
Biology
Physics
Astronomy
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Philosophy
Ethics
Politics
Rhetoric
Aesthetics
Psychology
Biology
Physics
Astronomy
Economics
Friday, September 18, 2009

Philosophy
Ethics
Politics
Rhetoric
Aesthetics
Psychology
Biology
Physics
Astronomy
Economics
Logic
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(practical) wisdom
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(practical) wisdom
aiming at virtues
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(practical) wisdom
aiming at virtues
combined with moral strength
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(practical) wisdom
aiming at virtues
combined with moral strength
leading to happiness
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(practical) wisdom
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aiming at
virtues
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Courage
Temperance
Pride
Generosity
Good temper
Truthfulness
Wit
Friendliness
Modesty
Righteous
Indignation
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Excess (too much) Virtue (just right) Defect (too little)
Rashness Courage Cowardice
Temperance
Pride
Generosity
Good temper
Truthfulness
Wit
Friendliness
Modesty
Righteous
Indignation
Friday, September 18, 2009

Excess (too much) Virtue (just right) Defect (too little)
Rashness Courage Cowardice
Indulgence Temperance Insensibility
Vanity Pride Lack of ambition
Prodigality Generosity Illiberality
Irascability Good temper Lack of spirit
Boastfulness Truthfulness False Modesty
Buffoonery Wit Boorishness
Obsequiousness Friendliness Cantankerousness
Shyness Modesty Shamelessness
Righteous
Envy Spitefulness
Indignation
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combined with
moral strength
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leading to happiness
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modeling
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practice
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bootstrapping
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Downsides
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Virtue-based
software development
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Act - Effect
Actor
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Process - Outcome
Participants
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Education and training
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Pride
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Sane work schedules
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Empower developers
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Mentoring
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Right people -> right outcomes
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What kind of agile?
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Natural
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Empower
programmers
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Self-effacing
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Pleasant to write
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Happy and virtuous
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virtues, not rules
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virtues, not rules
moderation, not excess
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virtues, not rules
moderation, not excess
judgment, not process
Friday, September 18, 2009

virtues, not rules
moderation, not excess
judgment, not process
whole of life
Friday, September 18, 2009

virtues, not rules
moderation, not excess
judgment, not process
whole of life
happiness
Friday, September 18, 2009

Thanks!
Slides at:
http://railspikes.com
Aristotle, Nicomachean Ethics
Friday, September 18, 2009