> ## Documentation Index
> Fetch the complete documentation index at: https://docs.stateset.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Contradict a belief (decrease confidence)

> **Required scope:** write

**Required scope:** `write`

### Request body

`ModifyBeliefRequest`

<ParamField body="proposition" type="string" required>
  The proposition to modify
</ParamField>

<ParamField body="source" type="string">
  Source of the evidence
</ParamField>

<ParamField body="strength" type="number (float)" required>
  Strength of the support/contradiction (0.0 to 1.0)
</ParamField>

### Response

`ModifyBeliefResponse`

<ResponseField name="change" type="number (float)" required />

<ResponseField name="new_confidence" type="number (float)" required />

<ResponseField name="previous_confidence" type="number (float)" required />

<ResponseField name="proposition" type="string" required />

### Status codes

| Code  | Meaning                                            |
| ----- | -------------------------------------------------- |
| `200` | Belief contradicted                                |
| `401` | Unauthorized — missing or invalid credentials      |
| `403` | Forbidden — the key/token lacks the required scope |
| `404` | Belief not found                                   |
| `429` | Rate limited — see Retry-After / X-RateLimit-Reset |

<RequestExample>
  ```bash cURL theme={null}
  curl --request POST \
    --url 'https://api.nsr.stateset.com/api/v1/beliefs/contradict' \
    --header 'X-API-Key: YOUR_API_KEY' \
    --header 'Content-Type: application/json' \
    --data '{
    "proposition": "socrates_is_mortal",
    "source": "inference",
    "strength": 0.3
  }'
  ```
</RequestExample>

<ResponseExample>
  ```json 200 theme={null}
  {
    "change": 1.5,
    "new_confidence": 7.5,
    "previous_confidence": 7.5,
    "proposition": "string"
  }
  ```
</ResponseExample>