Idea groups

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Ideas interface
For the ideas of individual countries, see national ideas.
For the ideas of American natives, see native ideas.

As a nation develops technologically, it unlocks the ability to gain additional idea groups. Investing into a full idea group can take a long time and cost several decades worth of power. The act of choosing at any point of time a certain idea group over the other and advancing in it represent the time and focus nations choose to spend historically along certain administrative, diplomatic, and military specializations.

Mechanic summary[edit]

Each nation can have up to 8 idea groups from a pool of 19 groups (only 18 are shown as 2 ideas are government type exclusive). The sole restriction on the groups is in regards to their composition; meaning, a group can only be picked as long as its affiliated All power costs.png monarch power doesn't consist more than 50%[1] of the idea group composition the nation holds at the time. This limit can be turned off before starting a game and works on Ironman. There is no restriction on the groups themselves and any nation may pick any group at any point in the game. That being said, AI nations have had weights assigned to the idea groups to simulate random but somewhat historical idea picks.

Each idea group itself consists of 7 ideas. Advancing within an idea group is done sequentially and each unlocked idea enhances a certain aspect of the nation. Unlocking the last idea in the group also unlocks the group bonus.

Unlocking new slots[edit]

New idea group slots are unlock with the advancement in Administrative tech.png Administrative technology as described below:

Administrative tech.png Administrative tech level 5 7 10 14 18 22 26 29
Idea unlock Number of idea groups 1 2 3 4 5 6 7 8

Abandoning idea groups[edit]

Abandoning an idea group can be used to free up an idea slot if it is no longer serves the nation and there may be others more suitable groups who do so. It is important to note, however, that doing so will result in losing all the given bonuses from said idea group and will only refund 10% of the All power costs.png monarch power points invested in the group[2]. Discarding idea groups will also impact the number of Ideas a nation has towards unlocking National Ideas and Ambitions.

Due to the low refund rate and the importance of monarch power points, picking an idea group should be done with its future usefulness to the nation in mind. However, this option should not be disregarded either as it is extremely useful in the right circumstances. For example:

  • Primitives can take only the first 3-4 Exploration ideas, get a colonial border with a western power, then drop Exploration for something else, some would benefit more from Expansion idea group; but Expansion doesn't allow Explorers or long-range island-hopping). They could even opt out of colonization altogether after getting the border they needed.
  • Primitive nations may take the first 2 ideas of the Aristocratic idea group (for +50% hostile core creation cost) to reduce the chances of a colonial power declaring war on them while they try to reform their nation

Technology cost reduction[edit]

Each unlocked idea grants a Technology cost.png -2% Technology cost reduction. The reduction can result in up to -14% for a fully unlocked idea group (without accounting for further reductions that may be applied from the ideas themselves). The type of the reduction depends on the affiliation of the idea group; for example, the Espionage idea group.png Espionage idea group grants Diplomatic technology cost Diplomatic tech cost reduction.


Main article: Policies

Policies become enabled when a pair of 2 idea groups are fully unlocked. Picking a Policies.png policy provides a bonus to the nation at the monthly cost of 1 monarch power per policy (monarch type depends on policy affiliation). Once picked a policy cannot be canceled for a duration of Time Icon.png 10 years. There is no restriction on policy composition and a nation can activate up to 5 policies at a time.

Idea cost.pngIdea cost[edit]

Unlocking an idea has a base idea cost of All power costs.png 400 monarch power[3] (the type of power depending on the idea group).

The base Idea cost.png Idea cost is modified by the following:

Idea cost.png Conditions
−25% for the AI at very hard difficulty
−10% with ProtestantismProtestant as secondary faith
−5% with a ruler which has the ‘Free Thinker’ personality
−5% as Mahayana.pngMahayana country
−5% with “Individual creeds” aspect as ProtestantismProtestant country
+0.2% for each point of doom of Nahuatl.png Nahuatl countries
+20% during the Dominance of the Clergy disaster
+25% during the Janissary Decadence disaster as Flag of Ottomans Ottomans
+50% during the Dominance of the Tribes disaster

Ideas and policies:

Idea cost.png Traditions Ideas Bonuses Policies
  • Aztec traditions
  • Incan traditions
  • Ming traditions
  • Rostov traditions
  • Antemoro idea 2: Sorabe
  • Aymaran idea 1: Legacy of Tiwanaku
  • Bahmani idea 7: Great Madrasa of the Deccan
  • Cherokee idea 4: Cherokee Adaptability
  • Colonial idea 4: Free Thinkers
  • Daimyo idea 2: The Bun and the Bu
  • Date idea 3: Renga Group
  • Greek idea 7: Greek Enlightenment
  • Hamburger idea 5: School of the Johanneum
  • Hessian idea 2: Marburg University
  • Imagawa idea 3: History of the Imagawa
  • Korean idea 6: The Kyujanggak
  • Leonese idea 4: School of Salamanca
  • Maravi ideas 1: Fresh Perspectives
  • Mesoamerican idea 1: Olmec Legacy
  • Mexican idea 4: Casa de las Campanas
  • Milanese idea 1: Renaissance Prince
  • Mughal idea 4: Ibadat Khana - House of Worship
  • Native idea 2: Storytelling Tradition
  • Navarran idea 6: Royal Basque Society
  • Northumbrian idea 6: The Literary and Philosophical Society
  • Orleanaise idea 6: Calvin and Molière
  • Polotskian idea 3: Cultural Center
  • Savoyard idea 5: Savoyard Flexibility
  • Shawnee idea 4: Shaawanwaki Identity
  • Takeda idea 5: Koshu Hatto
  • Thüringian idea 6: Weimar Classicism
  • Tibetan idea 7: The Pale Earth School
  • Toki idea 6: Innovation over Tradition
  • Trebizondian idea 3: Legacy of the Alexiad
  • Tsutsui idea 7: Tradition and Innovation
  • Uesugi idea 7: Denoku no Ji
  • Welsh idea 6: Prifysgolion Cymru
  • Full Humanist
  • Granadan ambition
  • Humanist-Trade: Exchange of Ideas
  • Italian idea 1: Italian Renaissance
  • Malayan sultanate idea 4: Classical Malay
  • Swahili idea 4: Indian Ocean Melting Pot
  • Tuscan idea 1: Birthplace of the Renaissance

Decisions and events:

Idea cost.png Event modifier Trigger Duration
+5% Counter-Reformation Catholic decision: “Embrace the Counter-Reformation until one of the following:
  • event: “The Counter-Reformation Ends” (2051): The reformation started 150 years ago.
  • event: “The Counter-Reformation Ends” (2050) for non-Catholic countries.
  • event: “The Counter-Reformation Ends” (2052): has the idea: Liberté, Égalité, Fraternité.
  • event: “The Counter-Reformation Ends” (2053): has the idea: Ecumenism.
  • event: “The King of the Jesuits” option ‘Religious Freedom won the day’.
−5% Islamic center of Scholarly Learning Muslim decision: “Establish an Ibadat Khana until the state religion is changed.
−10% Expanded Royal Bureaucracy Ottoman event: “The Expansion of the Royal Bureaucracy
Option: ‘Expand the Royal Bureaucracy’
until ruler changes.
−10% Kösem Sultana Ottoman event: “Kösem Sultana
Option: ‘Wed Kösem’
until one of the following:
  • until ruler changes.
  • until event: “The Murder of Kösem”
+25% Powerful Magnates Hungarian event: “Decline of Royal Power
Option: ‘Allow the Magnates free reign’
until ruler changes.
−10% Renaissance Glory Neapolitan event: “Renaissance in Naples
Option: ‘An age of Glory!’
for 20 years.
−5% Reichshofrat Austrian event: “Reichshofrat
Option: ‘Create this new council’
for the rest of the campaign.
−10% Reform of the Bureaucracy Austrian event: “The Reform of the Bureaucracy
Option: ‘Reform’
for 20 years.
−25% Prussian Reforms of Enlightenment Prussian event: “The Enlightened Reforms of Frederick the Great
Option: ‘Reforms of Enlightenment’
until ruler changes.
−25% Prutenic Tables Prussian event: “Prutenic Tables
Option: ‘Finance the printing’
until ruler changes.
+10% Sejm Veto Polish culture event: “The Sejm veto all your policies
Option: ‘Ok’
until ruler changes or the event “Pacify the Sejm”.
−10% Sejm complied Polish culture event: “The Sejm comply to your policies
Option: ‘Great!’
until ruler changes or the event “Pacify the Sejm”.
−10% Sigismund's Column Polish event: “Sigismund's Column
Option: ‘Construct Sigismund's Column’
for 30 years.
−5% Merkuriusz Polski Ordynaryjny Polish event: “Merkuriusz Polski Ordynaryjny
Option: ‘Sponsor the newspaper’
until ruler changes.
+25% Konfederacja Polish culture event: “Konfederacja”
Option: ‘Try to negotiate with the konfederacja’
until ruler changes.
+10% Closed China Ming event: “The Closure of China
Option: ‘Close China to the outside world’
for the rest of the campaign.
−10% Open China Ming event: “The Closure of China
Option: ‘Keep trade open for all’
for the rest of the campaign.
−15% Genroku Japanese culture event: “Genroku-era
Option: ‘Start the era of Genroku!’
for 10 years.
−5% Kokugaku Japanese culture event: “Kokugaku
Option: ‘Support the thinkers’
for the rest of the campaign.
−10% Gossip Japanese culture event: “Spreading Rumors
Option: ‘No need to spread foul rumors’
−25% Astadiggajas Vijaynagari event: “Astadiggajas
Option: ‘Let the Prabandha Age begin’
for 60 years. until ruler changes.
−20% Golden age of Timbuktu Songhain event: “Golden Age in Timbuktu
Option: ‘This will last forever...’
until ruler changes.
−5% An Independent Church Ethiopian event: “Independence from the Patriarchate
Option: ‘Our Church should be free of foreign influence.’
for maximum 10 years or until the state religion changes.
−5% Andalucian Moors Moroccan event: “Moorish Refugees for 10 years.
−5% Shiite Migration Persian event: “Shiite Brain Drain
Option: ‘Welcome our brothers.’
for 20 years.
−5% Moorish Refugees Muslim event after the fall of Granada for 25 years.
−10% Celestial Globe[4] Muslim event: “Muhammad Salih Tahtawi - The Celestial Globe
Option: ‘Accept the globe and urge him to create more’
for 20 years.
−5% Mian Mir[4] Muslim event: “Mian Mir
Option: ‘Ask him for advise’
until ruler changes.
−5% Reza Abbasi[4] Muslim event: “Reza Abbasi
Option: ‘Support him and his art’
until ruler changes.
−5% Baha al-din al-Amili[4] Muslim event: “Baha al-din al-Amili
Option: ‘He shall have our support’
until ruler changes.
−5% Serafeddin Sabuncuoglu[4] Muslim event: “Serafeddin Sabuncuoglu
Option: ‘With our help, he shall be able to practice medicine for many more year’
until ruler changes.
−5% Al-Birjandi[4] Muslim event: “Al-Birjandi
Option: ‘I will support his work’
until ruler changes.
−10% Free Freethinkers Event: “Freethinkers Not Persecuted
Option: ‘Brilliant!’
for 10 years.
−10% American Academy of Arts and Sciences[5] American event: “American Academy of Arts and Sciences
Option: ‘Sponsor the academy’
for 20 years.
−20% American Philosophical Society[5] American event: “American Philosophical Society
Option: ‘Sounds impressive, let's sponsor it’
for 20 years.
−20% Sistine Chapel decorated by Michelangelo Papal states event: “Decorate the Sistine Chapel
Option: ‘Hire Michelangelo.’
for the rest of the campaign.
−10% Accademia del Cimento Tuscan event: “Accademia del Cimento
Option: ‘Scientific societies sound like they could be useful someday. Maybe.’
for 10 years.
−5% The Medici Oriental Press Tuscan event: “The Medici Oriental Press for 30 years.
−10% Innovative Court Personality event: “Heresiarch?
Option: ‘The world as a Cheese with worms? Fascinating perspective!’
until ruler changes.

National ideas[edit]

Main article: National ideas

Every country has seven national ideas (NI). These ideas do not cost any monarch points but instead are unlocked; one national idea is unlocked for every third idea bought normally from an idea group.

Many nations have unique national ideas while a large number of others have national ideas based upon a common geographic region or a shared culture. The rest of the nations, who lack unique NIs or don't share a common NI group, draw their national ideas from a common generic set of ideas.

New national ideas are added to the game with every patch and it was declared as a goal to replace every generic set ideas with a unique one or the very least with a group based one.

National tradition
Every nation also starts with a national tradition: two abilities which define the history and heritage of the country.
National ambition
Countries also have a “national ambition”, which is a bonus that is unlocked when a nation has gained all seven of its national ideas. This bonus is also unique for each country.

Administrative power.png Administrative groups[edit]

Administrative power is required to unlock ideas within these groups.

Administrative idea group.png Administrative

Mercenary cost.png Organized Mercenary Payments
−25% Mercenary cost

Core-creation cost.png Adaptability

−25% Core-creation cost

Mercenary maintenance.png Benefits for Mercenaries

−25% Mercenary maintenance

Interest per annum.png Bookkeeping

−1 Interest per annum

Available mercenaries.png Mercenary Recruitment

+25% Available mercenaries

Possible advisors.png Administrative Efficiency

+1 Possible advisors

Administrative technology cost.png Civil Service

−10% Administrative technology cost

Idea bonus.png Bonus:

+5 Number of states

Associated events: Administrative idea group events

Economic idea group.png Economic

National tax modifier.png Bureaucracy
+10% National tax modifier

Construction cost.png Organized Construction

−10% Build cost

Inflation reduction.png National Bank

+0.10 Yearly inflation reduction

Interest per annum.png Debt and Loans

−1 Interest per annum

Autonomy.png Centralization

−0.05 Monthly autonomy change

Land maintenance modifier.png Nationalistic Enthusiasm

−10% Land maintenance modifier

Production efficiency.png Smithian Economics

+10% Production efficiency

Idea bonus.png Bonus:

−20% Development cost

Associated events: Economic idea group events

Expansion idea group.png Expansion

Colonists.png Additional Colonists
+1 Colonists

Merchants.png Additional Merchants

+1 Merchants

Global settler increase.png Faster Colonists

+10 Global settler increase

Recruitment time.png Organized Recruitment

−10% Recruitment time

Diplomatic relations.png Additional Diplomats

+1 Diplomatic relations

Shipbuilding time.png Improved Shipyards

−10% Shipbuilding time

Trade power.png Competitive Merchants

+20% Global trade power

Idea bonus.png Bonus:

−25% State maintenance
Can fabricate claim overseas in trade company regions.

Associated events: Expansion idea group events

Humanist idea group.png Humanist

Religious unity.png Tolerance
+25% Religious unity

National unrest.png Local Traditions

−2 National unrest

Tolerance heretic.png Ecumenism

+3 Tolerance of heretics

Years of separatism.png Indirect Rule

−10 Years of separatism

Max promoted cultures.png Cultural Ties

+2 Max promoted cultures

Improve relations.png Benevolence

+30% Improve relations

Tolerance heathen.png Humanist Tolerance

+3 Tolerance of heathens

Idea bonus.png Bonus:

−10% Idea cost
+0.25 Yearly harmony increase

Associated events: Humanist idea group events

Innovative idea group.png Innovative

Prestige decay.png Patron of the Arts
−1% Prestige decay

Mercenary maintenance.png Pragmatism

−25% Mercenary maintenance

Technology cost.png Scientific Revolution

−10% Technology cost
−10% Institution embracement cost

Possible advisors.png Dynamic Court

+1 Possible advisors

Reduce inflation cost.png Resilient State

−10% Reduce inflation cost

War exhaustion.png Optimism

−0.05 Monthly war exhaustion

Leader(s) without upkeep.png Formalized Officer Corps

+1 Leader(s) without upkeep

Idea bonus.png Bonus:

−25% Advisor costs

Associated events: Innovative idea group events

Religious idea group.png Religious

Missionaries.png Missionary Schools
+1 Missionaries

Stability cost modifier.png Church Attendance Duty

−25% Stability cost modifier

Missionary strength.png Divine Supremacy

+3% Missionary strength

Tolerance own.png Devoutness

+1 Tolerance of the true faith
+2 Yearly papal influence
+0.25 Monthly fervor
+0.5 Yearly devotion
+10% Church power

Prestige.png Religious Tradition

+1 Yearly prestige

Missionary strength vs heretics.png Inquisition

+2% Missionary strength vs heretics

Cb on religious enemies.png Deus Vult

Permanent casus belli against neighboring heathens and heretics

Idea bonus.png Bonus:

−25% Culture conversion cost

Associated events: Religious idea group events

Diplomatic power.png Diplomatic groups[edit]

Diplomatic power is required to unlock ideas within these groups.

Diplomatic idea group.png Diplomatic

Diplomat.png Foreign Embassies
+1 Diplomats

Diplomatic relations.png Cabinet

+1 Diplomatic relations

Cost of reducing war exhaustion.png War Cabinet

−33% Cost of reducing war exhaustion

Improve relations.png Benign Diplomats

+25% Improve relations

Diplomatic reputation.png Experienced Diplomats

+2 Diplomatic reputation

Province warscore cost.png Flexible Negotiations

−20% Province warscore cost

Diplomatic technology cost.png Diplomatic Corps

−10% Diplomatic technology cost

Idea bonus.png Bonus:

Lowered impact on stability from diplomatic actions

Associated events: Diplomatic idea group events

Espionage idea group.png Espionage

Spy network construction.png Efficient Spies
+50% Spy network construction
−10% Advisor costs

Diplomat.png Agent Training

+1 Diplomats

Trade power.png Vetting

+10% Provincial trade power modifier
+33% Foreign spy detection

Liberty desire in subjects.png Additional Loyalist Recruitment

−10 Liberty desire in subjects

Cost to fabricate claims.png Claim Fabrication

−25% Cost to fabricate claims

Embargo efficiency.png Privateers

+25% Embargo efficiency
+33% Privateer efficiency

Yearly corruption.png Audit Checks

−0.10 Yearly corruption

Idea bonus.png Bonus:

+50% Rebel support efficiency

Associated events: Espionage idea group events

Exploration idea group.png Exploration

Colonists.png Colonial Ventures
+1 Colonists

May explore.png Quest for the New World

Allows recruitment of explorers and conquistadors.

Colonial range.png Overseas Exploration

+50% Colonial range

Global settler increase.png Land of Opportunity

+20 Global settler increase

Global tariffs.png Viceroys

+20% Global tariffs

Colonists.png Free Colonies

+1 Colonists

Naval force limit modifier.png Global Empire

+25% Naval force limit modifier

Idea bonus.png Bonus:

Can fabricate claim overseas in colonial regions.

Associated events: Exploration idea group events

Influence idea group.png Influence

Income from vassals.png Tribute System
+25% Income from vassals

Prestige.png Establish Cadet Branches

+0.50 Yearly prestige
+0.25 Chance of new heir

Diplomatic annexation cost.png Integrated Elites

−25% Diplomatic annexation cost

Aggressive expansion impact.png State Propaganda

−20% Aggressive expansion impact

Diplomatic reputation.png Diplomatic Influence

+2 Diplomatic reputation

Envoy travel time.png Postal Service

+1 Diplomatic relations
−25% Envoy travel time

Vassal forcelimit bonus.png Marcher Lords

+100% Vassal force limit contribution

Idea bonus.png Bonus:

−50% Unjustified demands

Associated events: Influence idea group events

Maritime idea group.png Maritime


Not available for primitives.

Navy tradition.png Seahawks

+1 Yearly navy tradition

National sailors modifier.png Merchant Marine

+50% National sailors modifier

Global ship repair.png Sheltered Ports

+10% Global ship repair
−10% Sailor maintenance

Naval force limit modifier.png Grand Navy

+50% Naval force limit modifier

Ship costs.png Ship's Penny

−10% Ship costs

Naval leader maneuver.png Excellent Shipwrights

+2 Naval leader maneuver

Blockade efficiency.png Naval Fighting Instruction

+50% Blockade efficiency

Idea bonus.png Bonus:

Ships can repair when in coastal sea zones

Associated events: Maritime idea group events

Trade idea group.png Trade

Trade power.png Shrewd Commerce Practice
+20% Global trade power

Merchants.png Free Trade

+1 Merchants

Trade range.png Merchant Adventures

+25% Trade range

Trade efficiency.png National Trade Policy

+10% Trade efficiency

Merchants.png Overseas Merchants

+1 Merchants

Trade steering.png Trade Manipulation

+25% Trade steering

Caravan power.png Fast Negotiations

+25% Caravan power

Idea bonus.png Bonus:

+1 Merchants

Associated events: Trade idea group events

Military power.png Military groups[edit]

Military power is required to unlock ideas within these groups.

Aristocratic idea group.png Aristocratic


Only available to monarchies and theocracies.

Cavalry cost.png Noble Knights

−10% Cavalry cost
+10% Cavalry combat ability

Military technology cost.png Military Traditions

−10% Military technology cost

Autonomy.png Local Nobility

−0.025 Monthly autonomy change
+0.1 Yearly absolutism

National manpower modifier.png Serfdom

+33% National manpower modifier

Army tradition decay.png Noble Officers

−1% Yearly army tradition decay
−1% Yearly navy tradition decay

Diplomat.png International Diplomacy

+1 Diplomats
+1 Leader(s) without upkeep

Available mercenaries.png Noble Connections

+20% Available mercenaries

Idea bonus.png Bonus:

+1 Land leader siege

Associated events: Aristocratic idea group events

Defensive idea group.png Defensive

Army tradition.png Battlefield Commissions
+1 Yearly army tradition

Morale of armies.png Military Drill

+15% Morale of armies

Land leader maneuver.png Improved Maneuver

+1 Land leader maneuver

Land maintenance modifier.png Regimental System

−10% Land maintenance modifier

Fort maintenance.png Defensive Mentality

+20% Fort defense
−10% Fort maintenance

Reinforce speed.png Supply Trains

+33% Reinforce speed

Land attrition.png Improved Foraging

−25% Land attrition

Idea bonus.png Bonus:

+1 Attrition for enemies

Associated events: Defensive idea group events

Naval idea group.png Naval


Not available for primitives.

Naval leader shock.png Boarding Parties

+1 Naval leader shock

Galley combat ability.png Improved Rams

+25% Galley combat ability

Naval leader fire.png Naval Cadets

+1 Naval leader fire
−33% Morale hit when losing a ship

Prestige from naval battles.png Naval Glory

+100% Prestige from naval battles
+50% Naval Tradition from naval battles

Sailor recovery speed.png Press Gangs

+25% Sailor recovery speed

Heavy ship combat ability.png Oak Forests for Ships

+20% Heavy ship combat ability

Morale of navies.png Superior Seamanship

+10% Morale of navies
+10% Global naval engagement

Idea bonus.png Bonus:

+10% Ship durability

Associated events: Naval idea group events

Offensive idea group.png Offensive

Land leader shock.png Bayonet Leaders
+1 Land leader shock

Recruitment time.png National Conscripts

−10% Recruitment time

Land leader fire.png Superior Firepower

+1 Land leader fire

Prestige from land battles.png Glorious Arms

+100% Prestige from land battles

Siege ability.png Engineer Corps

+20% Siege ability

Land force limit modifier.png Grand Army

+20% Land force limit modifier

Discipline.png Esprit de Corps

+5% Discipline

Idea bonus.png Bonus:

+5% Recover army morale speed

Associated events: Offensive idea group events

Plutocratic idea group.png Plutocratic


Countries without access to aristocratic ideas get plutocratic ideas instead.

Available mercenaries.png Tradition of Payment

+10% Available mercenaries
+2.5% Mercenary discipline

Morale of armies.png Abolished Serfdom

+10% Morale of armies

National unrest.png Bill of Rights

−2 National unrest

Merchants.png Free Merchants

+1 Merchants

Goods produced modifier.png Free Subjects

+10% Goods produced modifier

Caravan power.png Free Cities

+25% Caravan Power

Manpower recovery speed.png Emancipation

+20% Manpower recovery speed

Idea bonus.png Bonus:

+10% Institution spread

Associated events: Plutocratic idea group events

Quality idea group.png Quality

Infantry combat ability.png Private to Marshal
+10% Infantry combat ability

Army tradition.png Quality Education

+1 Yearly army tradition

Cavalry combat ability.png Finest of Horses

+10% Cavalry combat ability

Ship durability.png Corvettes

+5% Ship durability

Morale of navies.png Naval Drill

+10% Naval morale

Naval attrition.png Copper Bottoms

−25% Naval attrition

Artillery combat ability.png Massed Battery

+10% Artillery combat ability

Idea bonus.png Bonus:

+5% Discipline

Associated events: Quality idea group events

Quantity idea group.png Quantity

National manpower modifier.png Levée en Masse
+50% National manpower modifier

Manpower recovery speed.png The Young can Serve

+20% Manpower recovery speed

Regiment cost.png Enforced Service

−10% Regiment cost

Land maintenance modifier.png The Old and Infirm

−10% Land maintenance modifier

Available mercenaries.png Mercenary Contracts

+25% Available mercenaries

Garrison size.png Conscripted Garrisons

+25% Garrison size

Land attrition.png Expanded Supply Trains

−10% Land attrition

Idea bonus.png Bonus:

+50% Land force limit modifier

Associated events: Quantity idea group events


Main article: List of idea group events

Idea group events are pulse based events. They occur at regular intervals (5 years) based on the nation's idea groups (not all groups are on the same interval).

In addition, the choice of ideas also has some influence in how often an event may happen, known as MTTH; meaning they can increase or decrease the likelihood of a certain to happened in over other events in their pulse group.

AI preference[edit]

Starting with patch 1.14 the choice of idea groups made by the AI is no longer determined by a pre-defined list in the history files but is, instead, dynamically determined according to the current conditions of the country.[6] To decide which idea group it should take, the AI employs a "weight system": each idea group is given a certain weight and the higher this weight is for an idea group, the higher the chances that the AI will choose it. The AI will never choose an idea group with a weight of 0.[7]

Idea group Base weight Weight modifiers[8]
Aristocratic idea group.png Aristocratic 0.25
Plutocratic idea group.png Plutocratic 0.4
Innovative idea group.png Innovative 0.3
  • ×2 the government type is Steppe Nomads
  • x2 has at least 20 provinces
  • x2 has at least 50 provinces
Religious idea group.png Religious 0.9
Espionage idea group.png Espionage 0.75
Diplomatic idea group.png Diplomatic 0.67
Offensive idea group.png Offensive 0.94
Defensive idea group.png Defensive 0.77
Trade idea group.png Trade 0.7
Economic idea group.png Economic 0.85
  • ×1.5 has at least 5 inflation
  • ×1.5 has at least 10 inflation
  • ×2 the government type is Steppe Nomads
  • x1.3 has at least 20 provinces
  • x1.3 has at least 50 provinces
Exploration idea group.png Exploration 0.75
Maritime idea group.png Maritime 0.41
  • ×0 is a tribe or primitive
  • ×0 if:
  • ×0.41 has less than 10 coastal provinces
  • ×0.41 has at least 50 provinces (no colonies)
Quality idea group.png Quality 0.49
Quantity idea group.png Quantity 1
Expansion idea group.png Expansion 0.48
Administrative idea group.png Administrative 0.96
Humanist idea group.png Humanist 0.9
Influence idea group.png Influence 0.5
Naval idea group.png Naval 0.31
  • ×0 is a tribe or primitive
  • ×0 if
  • ×0.31 has less than 10 coastal provinces
  • ×0.31 has at least 50 provinces (no colonies)


  1. See in /Europa Universalis IV/common/defines.lua: MAX_IDEA_GROUPS_FROM_SAME_CATEGORY = 0.5,
  2. See in /Europa Universalis IV/common/defines.lua: ABANDON_IDEAGROUP_REFUND = 0.10, -- The part of the idea group spent that will be refunded upon abandonment.
  3. See in /Europa Universalis IV/common/defines.lua: PS_BUY_IDEA = 400
  4. 4.0 4.1 4.2 4.3 4.4 4.5 Only available with Star and Crescent DLC.
  5. 5.0 5.1 Only available with American Dream DLC.
  6. It is still possible to revert to the old system by changing "AI_USES_HISTORICAL_IDEA_GROUPS" to 1 in /Europa Universalis IV/common/defines.lua. Note, however, that the AI will never use historical idea groups in a custom/random setup.
  7. The weights and their modifiers are defined in /Europa Universalis IV/common/ideas/00_basic_ideas.txt at the bottom of each idea group (ai_will_do)
  8. Multiple valid modifiers will stack
Monarch power RulerAdvisorIdea groupsNational ideasTechnologyStabilityPolicies
Other DecisionsMissionsEventsModifiersDisastersGovernmentFactionsPrestigeInstitutionsOverextensionWar exhaustionPower projection