- 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
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Please help with verifying or updating this section. It was last verified for version 1.31. |
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
 |
Available only with the Art of War DLC enabled. |
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.
PoliciesEdit
- 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
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|
Please help with verifying or updating this section. It was last verified for version 1.30. |
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:
|
|
Conditions |
|---|---|
| −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)
|
| −10% |
|
| −5% |
|
| +0.2% | as  Nahuatl countries for each point of doom
|
| +20% |
|
| +25% | during the Janissary Decadence  disaster
|
| +50% |
|
Ideas and policies:
|
Traditions | Ideas | Bonuses | Policies |
|---|---|---|---|---|
| −10% |
|
|
|
|
| −5% | — |
|
— | — |
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 groupsEdit
Administrative power is required to unlock ideas within these groups.
Administrative
Organized Mercenary Payments
- −10% Mercenary cost
Adaptability
- −25% Core-creation cost
Benefits for Mercenaries
- −15% Mercenary maintenance
Bookkeeping
- −0.5 Interest per annum
Mercenary Recruitment
- +25% Mercenary manpower
Administrative Efficiency
- +1 Possible advisor
Civil Service
- −10% Administrative technology cost
Bonus:
- +25% Governing capacity modifier
Associated events: Administrative idea group events
Economic
Bureaucracy
- +10% National tax modifier
Organized Construction
- −10% Construction cost
National Bank
- +0.10 Yearly inflation reduction
Debt and Loans
- −0.5 Interest per annum
Centralization
- −0.05 Monthly autonomy change
Nationalistic Enthusiasm
- −5% Land maintenance modifier
Smithian Economics
- +10% Production efficiency
Bonus:
- −10% Development cost
Associated events: Economic idea group events
Expansion
Additional Colonists
- +1 Colonist
Additional Merchants
- +1 Merchant
Faster Colonists
- +20 Global settler increase
Factories
- −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
Bonus:
- −10% Minimum autonomy in territories
Associated events: Expansion idea group events
Humanist
Tolerance
- +25% Religious unity
Local Traditions
- −2 National unrest
- +25% Religious harmonization speed
Ecumenism
- +2 Tolerance of heretics
Indirect Rule
- −10 Years of separatism
Cultural Ties
- +2 Max promoted cultures
Benevolence
- +30% Improve relations
Humanist Tolerance
- +2 Tolerance of heathens
Bonus:
- −10% Idea cost
- +0.25 Yearly harmony increase
- +10% Brahmins loyalty equilibrium for muslims
- +10% Dhimmi loyalty equilibrium
Associated events: Humanist idea group events
Innovative
Patron of the Arts
- −1% Prestige decay
Empiricism
- +50% Innovativeness gain
Scientific Revolution
- −10% Technology cost
- −10% Institution embracement cost
Dynamic Court
- +1 Possible advisor
Print Culture
- +25% Institution spread
Optimism
- −0.05 Monthly war exhaustion
- +1 Leader without upkeep
Expanded Policies
- +1 Free policies
Bonus:
- −25% Advisor costs
Associated events: Innovative idea group events
Religious
Missionary Schools
- +1 Missionary
Church Attendance Duty
- −25% Stability cost modifier
Divine Supremacy
- +3% Missionary strength
Devoutness
- +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
Inquisition
- +0.1 Prestige per development from Missionary
- −50% Missionary maintenance cost
Deus Vult
- Permanent casus belli against neighboring heathens and heretics
Bonus:
- −25% Culture conversion cost
- +10% Brahmins loyalty equilibrium
- +10% Clergy loyalty equilibrium
Associated events: Religious idea group events
Diplomatic groupsEdit
Diplomatic power is required to unlock ideas within these groups.
Diplomatic
Foreign Embassies
- +1 Diplomat
Cabinet
- +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
Bonus:
- Lowered impact on stability from diplomatic actions
Associated events: Diplomatic idea group events
Espionage
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
Vetting
- +33% Foreign spy detection
- -0.2 Yearly corruption
Privateers
- +33% Privateer efficiency
- +25% Chance to capture enemy ships
Blackmailing
- +15 Vassalization acceptance
- +33% Monthly favor gain modifier
Bonus:
- +100% Rebel support efficiency
- -100% Covert action relations impact
Associated events: Espionage idea group events
Exploration
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
Viceroys
- +10% Global tariffs
- −20% Envoy travel time
Free Colonies
- +10% Settler chance
Global Empire
- +25% Naval force limit modifier
- +25% Treasure fleet income
Bonus:
- Can fabricate claim overseas in colonial regions
Associated events: Exploration idea group events
Influence
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
Bonus:
- −50% Unjustified demands
Associated events: Influence idea group events
Maritime
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
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Seahawks
- +1 Leader without upkeep
- −25% Admiral cost
Naval Fighting Instruction
- +50% Blockade efficiency
- +25% Privateer efficiency
Bonus:
- Ships can repair when in coastal sea zones
- +1 Fleet movement speed
Associated events: Maritime idea group events
Trade
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
Bonus:
- +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 groupsEdit
Military power is required to unlock ideas within these groups.
Government-based idea groupsEdit
Aristocratic
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
Serfdom
- −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
Bonus:
- +1 Leader siege
- +10% Nobility loyalty equilibrium
Associated events: Aristocratic idea group events
Divine
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
Martyrs
- +20% Manpower in true faith provinces
Bonus:
- +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
Bonus:
- +25% Cavalry combat ability
- +10% Tribes loyalty equilibrium
Associated events: Horde Government idea group events
Indigenous
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
Braves
- +10% Morale of armies
Controlled Burns
- +15% National manpower modifier
Trade with Foreigners
- −10% Idea cost
Treaties Kept
- −20% Province warscore cost
Bonus:
- +25% Institution spread
Associated events: Indigenous idea group events
Plutocratic
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
Emancipation
- +20% Manpower recovery speed
Bonus:
- +10% Institution spread
- +10% Burghers loyalty equilibrium
- +10% Vaishyas loyalty equilibrium
Associated events: Plutocratic idea group events
General military idea groupsEdit
Defensive
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
Bonus:
- +1 Attrition for enemies
- +1 Max attrition for enemies
Associated events: Defensive idea group events
Naval
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
Bonus:
- -100% Naval barrage cost
- +15% Ship disengagement chance
Associated events: Naval idea group events
Offensive
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
Bonus:
- +5% Recover army morale speed
Associated events: Offensive idea group events
Quality
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
Corvettes
- +5% Ship durability
Naval Drill
- +10% Morale of navies
Copper Bottoms
- −25% Naval attrition
Massed Battery
- +10% Artillery combat ability
Bonus:
- +5% Discipline
Associated events: Quality idea group events
Quantity
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
Bonus:
- +25% Land force limit modifier
Associated events: Quantity idea group events
EventsEdit
- 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
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|
Please help with verifying or updating this section. It was last verified for version 1.33. |
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 |
|
 Religious
|
0.9 |
|
 Espionage
|
0.75 | |
| Diplomatic
|
0.67 |
|
 Offensive
|
0.94 | |
 Defensive
|
0.77 | |
 Trade
|
0.7 |
|
 Economic
|
0.85 |
|
 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 |
|
FootnotesEdit
- ↑ See in /Europa Universalis IV/common/defines.lua: MAX_IDEA_GROUPS_FROM_SAME_CATEGORY = 0.5,
- ↑ 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.
- ↑ See in /Europa Universalis IV/common/defines.lua: PS_BUY_IDEA = 400
- ↑ 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.
- ↑ 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).
- ↑ Multiple valid modifiers will stack
| Ideas and Policies | Idea groups • National ideas • Policies |
| Ages and Institutions | Ages • Institutions |
| Innovativeness and Technology | Innovativeness • Technology |
| Colonisation | Exploration • Colonisation • Colonial nation • Tariffs • Trade company |
| Economy | Debase currency • Development • Economy • Privateering • Production • Raid coasts • Tax |
| Trade | Trade • Trade company • Trade goods • Trade nodes |
| Diplomacy | Diplomacy • Diplomatic feedback • Envoy • Espionage |
| Other | Defender of the Faith • Great power • Hegemon • Prestige • Regions |
| Political structures | Emperor of China • Holy Roman Empire • Papacy |
| Relations | Personal union • Relations • Subject nation |
| Concepts | Corruption • Governing capacity • Overextension • Power projection • Rebellion • Regions • Stability • States and territories |
| Court | Advisors • Consort • Monarch power • National focus • Ruler • Ruler personalities |
| Estates and Factions | Base estates • Cossacks estates • Dharma estates • Estates • Factions |
| Events and Missions | Decisions • Disasters • Events • List of decisions • Missions |
| Goverment | Absolutism • Culture • Government • Government rank • Modifiers • Policies |
| Province mechanics | Autonomy • Buildings • Canal • Capital • Core • Province |
| Religions | Christian denominations • Eastern denominations • Muslim denominations • Other denominations • Pagan denominations • Religion |
| Specific governments | Native council • Parliament • Steppe hordes |
| Declaring war | Alliance • Casus belli • Claim • Peace • War exhaustion • Warfare |
| Defense | Fort • Zone of control |
| Land warfare | Army • Condottieri • Discipline • Drilling • Land units • Land warfare • Manpower • Militarisation • Mercenaries • Professionalism |
| Naval warfare | Flagship • Naval blockade • Naval doctrine • Naval units • Naval warfare • Navy • Sailors |
| Other | Force limit • Military leader • Military tradition |
