Europa Universalis 4 Wiki
For the ideas of individual countries, see national ideas.
For the ideas of American natives, see native ideas.
For the practical guide on idea groups, with analysis and recommendations, see Idea groups guide.

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.

Mechanics summaryEdit

Each nation can have up to 8 idea groups from a pool of 19 groups (only 18 are shown as the Aristocratic and Plutocratic idea groups are locked behind exclusive government reforms). Idea group choice is only restricted by the requirement for a balanced mix of groups: No more than half of a nation's chosen idea groups, whether completed or not, can have the same associated type of   monarch power.[1] This limit can be turned off in options before starting a game without disabling achievements.

Idea group choices are unrestricted, with several exceptions: Plutocratic ideas are enabled for most republics but disabled for most other government types; Aristocratic ideas are disabled for most republics but enabled for most other government types; Divine ideas are enabled only for theocracies; Horde Government ideas are enabled only for steppe nomads; Indigenous ideas are enabled only for native tribes and Maritime and Naval ideas are disabled for primitives. However, AI nations have weights assigned to the idea groups to make their choices random but still somewhat historical.

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

Unlocking new slotsEdit

New idea group slots are unlocked with the advancement in   Administrative technology as described below:

  Administrative tech level 5 7 10 14 18 22 26 29
  Number of idea groups 1 2 3 4 5 6 7 8
  Year in which the technology loses its ahead of time penalty 1453 1479 1518 1570 1622 1674 1730 1775

Abandoning idea groupsEdit

Abandoning an idea group can be used to free up an idea slot if it no longer serves the nation and there may be others more suitable groups that 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   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 the 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.

Technology cost reductionEdit

Each unlocked idea grants a   −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   Diplomatic idea group grants   Diplomatic tech cost reduction.

Innovativeness gainEdit

Being the first nation to unlock an idea or unlocking an idea within 365 days after it is first unlocked gives a nation a base of +2  innovativeness.


Main article: Policies

Policies become enabled when a pair of 2 idea groups are fully unlocked. Picking a   policy provides a bonus to the nation at the monthly cost of 1 monarch power per policy (type of monarch power used depends on policy affiliation) if the limit is overwhelmed (base: 1 policy of each type can be picked for free) . Once picked, a policy cannot be canceled for a duration of   10 years. There is no restriction on policy composition and a nation can activate up to 9 policies at a time, 3 per type.

Idea costEdit

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

The base   idea cost is modified by the following:

−25% for the AI at very hard difficulty
−1% per −1% modifier to   all power costs (up to −10% with 100 Innovativeness and another −10% during a Golden Era)
  • as  Tengri with  Protestant or  Anglican as secondary faith
  • as  Shinto with “Selective Integration” isolationism level
  • as  Confucian country harmonized with  Mahayana
  • with a ruler which has the   ‘Free Thinker’ personality
  • with ‘Mughal Diwan’ government with assimilation bonus for the Korean culture
  • as  Mahayana country
  • as  Protestant country with “Individual creeds” aspect
+0.2% as   Nahuatl countries for each point of doom
+25% during the Janissary Decadence   disaster

Ideas and policies:

  Traditions Ideas Bonuses Policies
  • Aztec traditions
  • Bregenzer traditions
  • Farsi traditions
  • Great Ming traditions
  • Incan traditions
  • Rostov traditions
  • Sardinian traditions
  • Sardinian-Piedmontese traditions
  • Urbinate traditions
  • Indigenous idea 6: Trade with Foreigners
  • American Southwest idea 1: The Old Tales
  • Andalusian idea 4: Legacy of Ibn Arabi
  • Antemoro idea 2: Sorabe
  • Aymaran idea 1: Legacy of Tiwanaku
  • Bahmani idea 7: Great Madrasa of the Deccan
  • Bengal Sultanate idea 4: Attract Sufi Scholars
  • Brunswicker idea 4: Herzog August Library
  • Central Algonquian idea 4: Teaching Scrolls
  • Cherokee idea 4: Cherokee Adaptability
  • Cilli idea 4: Slovenian Reformation
  • Colonial idea 4: Free Thinkers
  • Daimyo idea 2: The Bun and the Bu
  • Date idea 3: Renga Group
  • Deccani Sultanate idea 2: Promote Deccani Regional Identity
  • Epirote idea 4: Metropolis of Knowledge
  • Federation idea 4: Native Sign Language
  • Greek idea 7: Greek Enlightenment
  • Hamburger idea 5: School of the Johanneum
  • Hanseatic idea 6: Spread the Northern Style
  • Hessian idea 2: Marburg University
  • Hojo idea 3: Reform the Administration
  • Imagawa idea 3: History of the Imagawa
  • Korean idea 6: The Kyujanggak
  • Leonese idea 4: School of Salamanca
  • Lotharingian idea 4: New Carolingian Renaissance
  • Madyas idea 1: Hinilawod
  • Mainzian idea 2: Center of Religious Learning
  • Malaccan idea 7: Jawi Script
  • Mantuan idea 2: The Countess's Studiolo
  • Maravi idea 1: Fresh Perspectives
  • Mesoamerican idea 1: Olmec Legacy
  • Mexican idea 4: Casa de las Campanas
  • Milanese idea 1: Renaissance Prince
  • Moroccan idea 2: Sufi Marabouts
  • Mughal idea 3: 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
  • PLC idea 2: Jagiellonian University
  • Pisan idea 3: The University of Pisa
  • Polotskian idea 3: Cultural Center
  • Savoyard idea 5: Savoyard Flexibility
  • Shawnee idea 4: Shaawanwaki Identity
  • Siamese idea 1: Royal Poets
  • Takeda idea 5: Koshu Hatto
  • Thüringian idea 6: Weimar Classicism
  • Tibetan idea 7: The Pale Earth School
  • Toki idea 6: Innovation Over Tradition
  • Trebizond idea 3: Legacy of the Alexiad
  • Tsutsui idea 7: Tradition and Innovation
  • Uesugi idea 7: Denoku no Ji
  • Welsh idea 6: Prifysgolion Cymru
  • Westphalian idea 1: Jewish Rights
  • Full Humanist
  • Clevian ambition
  • Granadan ambition
  • Samoan ambition
  • Transoxianian ambition
  • Humanist-Trade: Exchange of Ideas
  • Frankfurter idea 1: Establish the Buchmesse
  • Italian (minor) idea 1: Italian Renaissance
  • Kilwan idea 4: Cultural Melting Pot
  • Malayan Sultanate idea 4: Classical Malay
  • Swahili idea 4: Indian Ocean Melting Pot
  • Tuscan idea 1: Birthplace of the Renaissance

Several missions, decisions and events grant modifiers that affect idea cost.

National ideasEdit

Main article: National ideas

Every country has seven national ideas. 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.

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 groupsEdit

Administrative power is required to unlock ideas within these groups.


  Organized Mercenary Payments
−10% Mercenary cost


−25% Core-creation cost

  Benefits for Mercenaries

−15% Mercenary maintenance


−0.5 Interest per annum

  Mercenary Recruitment

+25% Mercenary manpower

  Administrative Efficiency

+1 Possible advisor

  Civil Service

−10% Administrative technology cost


+25% Governing capacity modifier

Associated events: Administrative idea group events


+10% National tax modifier

  Organized Construction

−10% Construction cost

  National Bank

+0.10 Yearly inflation reduction

  Debt and Loans

−0.5 Interest per annum


−0.05 Monthly autonomy change

  Nationalistic Enthusiasm

−5% Land maintenance modifier

  Smithian Economics

+10% Production efficiency


−10% Development cost

Associated events: Economic idea group events


  Additional Colonists
+1 Colonist

  Additional Merchants

+1 Merchant

  Faster Colonists

+20 Global settler increase


−50% Fort maintenance on border with rival
−20% Center of trade upgrade cost

  Additional Diplomats

+1 Diplomatic relation

  General Colonization Law

+1 Colonist
+5% Settler chance

  Competitive Merchants

+20% Global trade power


−10% Minimum autonomy in territories

Associated events: Expansion idea group events


+25% Religious unity

  Local Traditions

−2 National unrest
+25% Religious harmonization speed


+2 Tolerance of heretics

  Indirect Rule

−10 Years of separatism

  Cultural Ties

+2 Max promoted cultures


+30% Improve relations

  Humanist Tolerance

+2 Tolerance of heathens


−10% Idea cost
+0.25 Yearly harmony increase
+10% Brahmins loyalty equilibrium for muslims
+10% Dhimmi loyalty equilibrium

Associated events: Humanist idea group events


  Patron of the Arts
−1% Prestige decay


+50% Innovativeness gain

  Scientific Revolution

−10% Technology cost
−10% Institution embracement cost

  Dynamic Court

+1 Possible advisor

  Print Culture

+25% Institution spread


−0.05 Monthly war exhaustion
+1 Leader without upkeep

  Expanded Policies

+1 Free policies


−25% Advisor costs

Associated events: Innovative idea group events


  Missionary Schools
+1 Missionary

  Church Attendance Duty

−25% Stability cost modifier

  Divine Supremacy

+3% Missionary strength


+2 Tolerance of the true faith
+2 Yearly papal influence
+0.5 Yearly devotion
+0.25 Monthly fervor
+10% Church power
+0.1 Monthly piety accelerator
+10% Yearly karma decay
+1 Yearly doom reduction
+0.15 Yearly authority
+0.5% Yearly patriarch authority

  Religious Tradition

+1 Yearly prestige


+0.1 Prestige per development from Missionary
−50% Missionary maintenance cost

  Deus Vult

Permanent casus belli against neighboring heathens and heretics


−25% Culture conversion cost
+10% Brahmins loyalty equilibrium
+10% Clergy loyalty equilibrium

Associated events: Religious idea group events

Diplomatic power.png Diplomatic groupsEdit

Diplomatic power is required to unlock ideas within these groups.


  Foreign Embassies
+1 Diplomat


+1 Diplomatic relation

  Grand Banquets

+1 Diplomat

  Benign Diplomats

+25% Improve relations

  Experienced Diplomats

+2 Diplomatic reputation

  Flexible Negotiations

−20% Province warscore cost

  Diplomatic Corps

−10% Diplomatic technology cost


Lowered impact on stability from diplomatic actions

Associated events: Diplomatic idea group events


  Claim Fabrication
May fabricate claims for subjects
−25% Cost to fabricate claims

  State Propaganda

−20% Aggressive expansion impact

  Efficient Spies

+50% Spy network construction
+10% Siege ability

  Agent Training

+1 Diplomat
−15% Advisor cost


+33% Foreign spy detection
-0.2 Yearly corruption


+33% Privateer efficiency
+25% Chance to capture enemy ships


+15 Vassalization acceptance
+33% Monthly favor gain modifier


+100% Rebel support efficiency
-100% Covert action relations impact

Associated events: Espionage idea group events


  Quest for the New World
Allows recruitment of explorers & conquistadors

  Colonial Ventures

+1 Colonist

  Overseas Exploration

+50% Colonial range

  Land of Opportunity

+10 Global settler increase


+10% Global tariffs
−20% Envoy travel time

  Free Colonies

+10% Settler chance

  Global Empire

+25% Naval force limit modifier
+25% Treasure fleet income


Can fabricate claim overseas in colonial regions

Associated events: Exploration idea group events


  Tribute System
+25% Income from vassals

  Additional Loyalist Recruitment

−15% Liberty desire in subjects

  Integrated Elites

−25% Diplomatic annexation cost

  Buffer States

+1 Diplomatic relation

  Diplomatic Influence

+2 Diplomatic reputation

  Postal Service

−25% Envoy travel time

  Marcher Lords

+100% Vassal force limit contribution


−50% Unjustified demands

Associated events: Influence idea group events



Not available for primitives.

  Merchant Traditions

+25% Trade range
+100% Naval tradition from protecting trade

  Merchant Marine

+50% National sailors modifier
+25% Marines force limit

  Sheltered Ports

+10% Global ship repair
−10% Sailor maintenance

  Grand Navy

+50% Naval force limit modifier
+25% Ship tradepower propagation

  Ship's Penny

−10% Ship costs


+1 Leader without upkeep
−25% Admiral cost

  Naval Fighting Instruction

+50% Blockade efficiency
+25% Privateer efficiency


Ships can repair when in coastal sea zones
+1 Fleet movement speed

Associated events: Maritime idea group events


  Shrewd Commerce Practice
+20% Global trade power

  Free Trade

+1 Merchant

  Merchant Adventures

+25% Trade range

  National Trade Policy

+10% Trade efficiency
-25% Cost to promote Mercantilism

  Overseas Merchants

+1 Merchant

  Trade Manipulation

+25% Trade steering

  Fast Negotiations

+25% Caravan power


+1 Merchant
+10% Burghers loyalty equilibrium
+10% Jains loyalty equilibrium
+10% Vaisyas loyalty equilibrium

Associated events: Trade idea group events
  • For Exploration note the hidden bonuses when using explorers: each terra incognita sea zone revealed through naval exploration grants +1 naval tradition.

Military power.png Military groupsEdit

Military power is required to unlock ideas within these groups.

Government-based idea groupsEdit



Enabled by most monarchies (except the Plutocracy and Feudal Theocracy reform), tribes (except steppe nomads and Great Mongol State), and the Noble Elite republican reform.

  Noble Knights

−20% Cavalry cost
+15% Cavalry combat ability

  Military Traditions

−10% Military technology cost

  Local Nobility

−0.025 Monthly autonomy change
+0.5 Yearly absolutism


−5% Development cost
+15% National manpower modifier

  Noble Officers

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

  International Diplomacy

+1 Diplomat
−10% General cost

  Noble Connections

+25% Mercenary manpower


+1 Leader siege
+10% Nobility loyalty equilibrium

Associated events: Aristocratic idea group events



Available for theocracies and countries with the Feudal Theocracy reform

  Servants of God

−5% Development cost
+1 Yearly devotion
+0.5 Yearly legitimacy

  By the Grace of God

−10% Fire damage received

  Friends in High Places

−33% Cost of reducing war exhaustion
−10% Leader cost

  Flesh Is Weak

+10% Morale of armies

  Alpha and Omega

−10% Culture conversion cost
−10% Cost of enforcing religion through war

  Conviction of Sin

−2 National unrest


+20% Manpower in true faith provinces


+1% Missionary strength vs heretics
+10% Clergy loyalty equilibrium
+10% Brahmins loyalty equilibrium

Associated events: Divine idea group events

  Horde Government


Enabled only for countries with the Steppe Nomads or Great Mongol State government reforms

  Horse-lords of the Steppes

−33% Cavalry cost
+10% Cavalry to infantry ratio

  Beyond the Sun

−10% Aggressive expansion impact

  Mandate of the Khan

+25% Religious unity

  There Shall Be No Grass

−20% Land attrition

  Horde Loyalty

−1 National unrest

  Watchers of the Silk Road

+20% Caravan power

  A Magnanimous Empire

+2 Max promoted cultures


+25% Cavalry combat ability
+10% Tribes loyalty equilibrium

Associated events: Horde Government idea group events



Only available for native tribes

  Bountiful Land

−5% Development cost
+0.015 Tribal development growth

  Irregular Warfare

+1 Attrition for enemies

  The Great Law

+25% Monthly reform progress modifier


+10% Morale of armies

  Controlled Burns

+15% National manpower modifier

  Trade with Foreigners

−10% Idea cost

  Treaties Kept

−20% Province warscore cost


+25% Institution spread

Associated events: Indigenous idea group events



Enabled by most republics (except the Noble Elite reform) and monarchies with the Plutocracy reform.

  Tradition of Payment

−20% Mercenary cost
+5% Mercenary discipline

  Abolished Serfdom

+10% Morale of armies

  Bill of Rights

−2 National unrest

  Free Merchants

+1 Merchant

  Free Subjects

+10% Goods produced modifier

  Free Cities

−5% Development cost
+25% Caravan power


+20% Manpower recovery speed


+10% Institution spread
+10% Burghers loyalty equilibrium
+10% Vaishyas loyalty equilibrium

Associated events: Plutocratic idea group events

General military idea groupsEdit


  Battlefield Commissions
+100% Army tradition from battles

  Military Drill

+15% Morale of armies

  Improved Maneuver

+1 Land leader maneuver

  Regimental System

−5% Land maintenance modifier

  Defensive Mentality

−10% Fort maintenance
+20% Fort defense

  Supply Trains

+33% Reinforce speed

  Improved Foraging

−25% Land attrition


+1 Attrition for enemies
+1 Max attrition for enemies

Associated events: Defensive idea group events



Not available for primitives.

  Boarding Parties

+1 Naval leader shock

  Improved Rams

+25% Galley combat ability

  Naval Cadets

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

  Naval Glory

+1 Yearly navy tradition
+1 Blockade impact on siege

  Press Gangs

+25% Sailor recovery speed
+25% Marines force limit

  Oak Forests for Ships

+20% Heavy ship combat ability
+10% Ship durability

  Superior Seamanship

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


-100% Naval barrage cost
+15% Ship disengagement chance

Associated events: Naval idea group events


  Bayonet Leaders
+1 Land leader shock

  National Conscripts

−10% Recruitment time

  Superior Firepower

+1 Land leader fire

  Glorious Arms

+100% Prestige from land battles

  Engineer Corps

+20% Siege ability

  Grand Army

+15% Land force limit modifier
+10% Special unit force limit

  Esprit de Corps

+5% Discipline


+5% Recover army morale speed

Associated events: Offensive idea group events


  Private to Marshal
+10% Infantry combat ability

  Quality Education

+0.5 Yearly army tradition
+0.5 Yearly navy tradition

  Finest of Horses

+10% Cavalry combat ability


+5% Ship durability

  Naval Drill

+10% Morale of navies

  Copper Bottoms

−25% Naval attrition

  Massed Battery

+10% Artillery combat ability


+5% Discipline

Associated events: Quality idea group events


  Levée en Masse
+25% National manpower modifier

  The Young can Serve

+20% Manpower recovery speed

  Enforced Service

−10% Regiment cost

  Camp Followers

+33% National supply limit modifier

  Conscripted Garrisons

+25% Garrison size

  The Old and Infirm

−5% Land maintenance modifier

  Expanded Supply Trains

−10% Land attrition


+25% 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 preferenceEdit

The AI is dynamically determined according to the current conditions of the country.[4] 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.[5]

Idea group Base weight Weight modifiers[6]
  Aristocratic 0.45
  Plutocratic 0.4
  Horde Government 20
  Divine 0.9
  Indigenous 1
  Innovative 0.3
  • ×2 has enacted “Steppe Nomads” government reform
  • x2 has at least 20 provinces
  • x2 has at least 50 provinces
  Religious 0.9
  Espionage 0.75
  Diplomatic 0.67
  Offensive 0.94
  Defensive 0.77
  Trade 0.7
  • ×0 does not use “Merchant Republic” mechanics and has fewer than 6 cities
  • x3 uses “Merchant Republic” mechanics
  Economic 0.85
  • ×1.5 has at least 5 inflation
  • ×1.5 has at least 10 inflation
  • ×2 has enacted “Steppe Nomads” government reform
  • x1.3 has at least 20 cities
  • x1.3 has at least 50 cities
  Exploration 0.75
  Maritime 0.41
  Quality 0.49
  Quantity 1
  Expansion 0.48
  Administrative 0.96
  Humanist 0.9
  Influence 0.5
  Naval 0.31


  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. 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.
  5. 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).
  6. Multiple valid modifiers will stack

Ideas and Policies Idea groupsNational ideasPolicies
Ages and Institutions AgesInstitutions
Innovativeness and Technology InnovativenessTechnology