Columbus Voyage Motives

Did Columbus mistake the distance of his voyage to India or were there other reasons to justify the venture?

Columbus misjudgment distance reason

15 results

Canelli's Underestimation of East Asia Distance Rejected by Portuguese

The user asks whether Columbus made a mistake about the distance to India or if there were other reasons to justify his voyage. I need to analyze both aspects.

From my search results, I can see clear evidence that:

Columbus severely miscalculated the distance
There were other motivations and justifications for the voyage

Key points from the sources:

Distance miscalculation:

Columbus thought the distance from Canary Islands to Japan was about 4,440 km (2,760 miles), when it's actually about 19,000 km (12,000 miles)
He underestimated Earth's circumference by 25%
Used Ptolemy's smaller degree measurement (50 miles) vs Eratosthenes' more accurate 60 miles, but actually used even less (45 miles)
Based on Toscanelli's calculations that East Asia was only 2,500 miles off Canary Islands
Portuguese experts correctly rejected his proposal saying his 2,400 nautical miles estimate was about four times too low

Other reasons/justifications:

Financial/political motives: Spain wanted to compete with Portugal for spice trade
Vague geographical concepts: "India" was a broad term for all of southern and eastern Asia
Access to spices: Goal was reaching Malabar, the "place of spices"
Religious motivations: Carried letter to "Emperor Khan of India"
National competition: Portugal had found eastern route via Africa, Spain wanted western route
Personal ambition: Columbus would be made Viceroy and get 10% of spoils
Confidence in dead reckoning: He used his navigation skills (99.7% correct heading)
Deception/manipulation: He kept two sets of logs to deceive crew about distance

I should structure this clearly, addressing both parts of the question with evidence from the sources.

Yes, Columbus severely miscalculated the distance to India, but there were also strong practical and political motivations that justified the venture despite his errors.

The Distance Error

Columbus's core miscalculation was dramatic:

He believed the Canary Islands to Japan was only 4,440 km (2,760 miles), when the actual distance is about 19,000 km (12,000 miles)
He underestimated Earth's circumference by 25%, using outdated maps and faulty measurements
He used the smallest possible degree measurement (45 nautical miles vs. the correct 60) to shrink the distance further
Portuguese experts correctly rejected his proposal, calculating his 2,400-nautical-mile estimate was "about four times too low"

Other Justifications for the Voyage

Despite this error, the expedition made sense for several reasons:

1. Commercial Competition Spain was locked in a race with Portugal for the lucrative spice trade. When Portugal found an eastern route around Africa, Spain had strong incentive to pioneer a western path.

2. Vague Geography Medieval Europeans used "India" as a broad term for all of southern and eastern Asia, including China and Japan. This mental flexibility made Columbus's goal seem more plausible.

3. Personal Rewards Columbus secured an agreement making him Viceroy of discovered lands and granting him 10% of all revenues.

4. Navigational Confidence Despite his distance error, Columbus's heading calculations were 99.7% accurate using dead reckoning. He trusted his ability to navigate, even if he couldn't measure distance correctly.

5. Deception as Strategy Columbus kept two sets of ship logs—one with false, shorter distances to pacify his crew and prevent mutiny when land failed to appear as expected.

6. Political Timing The voyage launched right after Spain's victory over the Moors in Granada, when Queen Isabella finally agreed to fund the expedition.

In essence, Columbus's mistake wasn't just a simple error—it was a willful underestimation that helped sell the voyage to sponsors, combined with genuine ambition and Spain's strategic need to compete in global trade.